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Begouen-BIOL205-Winter2015 LECTURE 2 : INTRO TO ORGANISM (review part 5) 1) Origins For creation of planet, size = super important. Since appeared, matter and E interacted H, C , He, Li First synthetised = Pre biological synthesis (elements synthetised before life appeared) Then radiation was used as an energy source and organic compounds were synthetised. Pre-biotic molecules complex arose = constant exchange of material and E with environment Life finally appeared !!! Life was bound to appear – a continuation of chemical evolution. Living state = non equilibrium – always evolve: Life needs both degradation and synthesis to occur allows system to maintain itself and avoid equilibrium But (according to first law thermodynamics) system always moves towards equilibrium. When reach equilibrium = death = no entropy 2) Chemical elements used in life Life possible thanks to H,C,N,O ( can all form long chain of polymer = multiple evolutionary possibilities) Special organisation of matter = self regulating/organising/renewing !!Possibility that life came from Si/Ammonium !! 3) Organisms characteristics THERMODYNAMICS CHARACT Can have some similar characteristic with non-living but non-living doesn’t have ALL of them Are thermodynamically open (take in food + E and reject waste) but organisationally closed + out of equilibrium - Will exchange with enviro, but energy remains constant Prygogine (scientist) : invented non equilibrium thermodynamics : Flow of energy in systems , that will organize it, state is maintained by flow – If flow changed, will change whole system allow to describes living system -Continuously replacement of our bodies: bones = 18 months, muscles = 3 months Organism = self organizing autopoietic system 1 Begouen-BIOL205-Winter2015 Organism = negative entropy : exchange with enviro but are not in equilibrium. Equilibrium = death HOMEOSTATIS -Homeostasis : maintenance of internal environment VS big change in exterior one ( Ex: If outside T go +20, inside T doesn’t change, we just sweat ) – Necessitates a feedback system that sense the disturbance and counter interact it Organism can be separated in conformers VS regulator (can shield itself from enviro) Regulator maintains homeostasis by regulation Control theory Degrees of regulation: homeostasis is only maintained to a certain point, after a limit, variability will change drastically. (Ex: Low T- until a certain T, body will fight and control it. After that – hypothermia –death (fail of the system)) How it works: Desired level = SET POINT Deviation are sensed by a SENSOR Sensed deviation are converted into a SIGNAL by a AMPLIFIER Then FEEDBACK Negative feedback= most common Ex: CO2 levels : Horse runs = Disturbance – CO2 rises- Nerve cells are triggered=SensorsSend signal to other part of brain hat control breathing- Signal sent to muscle - slow breathing = return to SET POINT Positive feedback: Deviation is increased until unstable system that will return to set point ex: Vomit, sneeze !!Some animal don’t control at all (E=1)!! = Conformers !! Some can regulate at first and then not – Some can regulate only after reaching a certain value!! Different organisms = different strategies to regulate environment (but NO perfect controller) GROWTH -Shape changes during growth, cannot be predicted mathematically (Allometric) Plants always grow, not animals Growth come with development (all change happening): Will acquire characteristic shape (morphogenesis) Cells will get their specifics functions (differentiation) Features are unique to organisms 2 Begouen-BIOL205-Winter2015 REPRODUCTION Simpler reproduction = asexual Higher = sexual: two different mating organisms and 2 different gametes. Go from haploid to diploids In higher plants = asexual and sexual (also Daphnea) Alternation of generations 4) Day to day process of organisms ENERGY ACQUISITIONS Need of E to counter entropy/ drive organisation (order and complexity) Organism needs E and low C Ultimate E source = SUN Based on needs of those two, organism can be divided into groups : Autotroph vs heterotrophs ACQUISITION AND TRANSPORT OF MAT IN/AROUND/OUT OF ORG Org need material from enviro, have to be transported through membrane + some need to be excreted + concentration gradient of ions in/out cell need to be maintained Transport in/out has to be strictly regulated Different transport types: A) Diffusion = only process if there is no air flow B) Osmosis = special diffusion, through membrane C) Convection = Rice in a pan D) Transport across cell membranes E) Endo/exocytose A) Diffusion- a transport process = Movements of molecule due to K energy ( !! Not to air flow= unfacilitated transport of molecules) random but goes away from region with higher C From High C to low C = down concentration gradient Rate of diffusion changes with concentration gradiant + membrane thickness Membrane thickness influences the diffusion coefficient Fast over short distance <-> very slow on long distance Ex: O2: 3 Begouen-BIOL205-Winter2015 - 1microm = 10-4 1mm=100s 1m = 3 year B) Osmosis= special diffusion = Diffusion with special condition Water move from one side of semi-permeable membrane to the other one Solvent will go through but not solute. Goes from higher water C to lower Speed = dependant on pore size C) Convection Driven by pressure difference – is used in supra-cellular distance (big one) Can be by air movement or in liquid – In ducts, tubes or vessels Moved by bulk flow – need of a pressure diff between beginning and end of vessel Flow rate (Q) = (P1-P2)/R . R = hydraulic resistance (depends on viscosity) Will increase with pressure and decrease with resistance D) Transport through cell membrane Many different types Some need E: active transport process can transport substance against C gradient 2 types depending on ATP use (direct or not) - ATP directly coupled = Primary active - Just pass through protein = Secondary active i) Both solutes in same direction = symport ii) Opposite directions = antiport iii) One solute in one direction = uniport Other have no need : passive transport process Follows C gradient . Use of channels ( can open and close- need stimulus to open) and of carriers (proteins anchored in membrane, binds with solute and changes membrane conformation) E) Endo/Exocytosis Endo = indulge, brought in Formation of cavity, prot comes in. Forms vesicle (separates from membrane) that will after go freely in cytoplasm Exo = expelled out cell Material is in vesicle that fuses with membrane and opens towards outside 4 Begouen-BIOL205-Winter2015 5) Implications of size of organism All organism grow in size A) Great variety B) Being bigger doesn’t mean bigger consumption C) Ratio CO2/size, becomes smaller as size grows Isometric growth: Growth follows the same proportion (everything has the same pace) If a=2A then b=2B and c=2C Allometric growth: can’t be mathematically measured, a=2A b=B c=3C <-> Growth = not proportional Surface will increase with volume but not in linear proportion, ratio will get smaller Metabolic proportion = Allometric (surface ^2 and volume^3 not the same) 5 Begouen-BIOL205-Winter2015 LECTURE 3 –ENERGY, LIGHT AND LIFE ( 9 janv) E= necessary for life, but where does it come from ? 1) Food and energy requirements of plants and animals Each org = syst of negative entropy Simple molecules are absorbed and then organized in more complex macromolec. Need of material and E to make it Plants and animals differ in need. - Plants receive E from Sunlight, but food from air or soil- need simple inorganic matter - Animals receive food & E at same time - Plants need E (sun), CO2 (air), mineral( soil) +seed non elaborated, simple food - Animals complex food, made by plants/other animals So plants = primary producers of E and food (do so through photosynthesis) 2) Composition if sunlight and interactions light/matter Light = both particle/wave = Small part of electromagnetic radiation from sun, in a 400nm to 700nm Plants Principal source E Sun. Energy comes from excitation of electron (induced by heating of photon) E is inversely proportional to wavelength E= h*c/wavelength Photons with higher energy are the one with shorter wave length Visible light ( especially those in violet ) Interaction of light& matter depends on material’s nature & on light’s nature : Short wavelength = high energy = too powerful, destroy stuff Visible wavelength photons =moderate energy= cause chemical reactions, most use, produce light and E High wavelength=low energy= only heat and no light ( infrared lamp) We are mainly concerned with photons from moderate energy quanta 3) Light receptors and pigments In light driven process, light must be absorbed by receptor. When light is in the correct range we can see colour receptor now called a pigments Pigments = conjugated to certain proteins. 6 Begouen-BIOL205-Winter2015 4) Action spectrum of photosynthesis + action spectrum of pigments Photosynthesis = process where light becomes biochemical energy Has an action spectrum telling us which wavelength makes the whole thing work + receptor/pigments that absorbs this specific wavelength When action spectrum of light process coincides with absorption spectrum pigment/receptor we can say that go together towards same process 5) Site of photosynthesis Chloroplast Reaction summary: Light energy captured, used to take e out of water liberates O2 e used to create NADPH, used to reduce C Photosynthesis characteristics - Happens in chloroplast (organelle with double membrane) - Where no membrane = Stroma = matrix - Grana (Granum) = stacks of thylakoid membranes (hollow membranes , space inside = lumen) 6) Photosynthetic pigments In thylakoids membrane photosynthetic pigments with conjugated protein - Several types of pigments : chloro + carotenoid - All eukaryotes have chloro-a , but other vary - 4 types of chlorophyll All pigments absorbing light: alternating double bounds. Why ? Cloud of electron covers it , and passes through it (pigment=good conductor)- facilitates e transmission electrical cord Action spectrum: Tells us rate of process under different wavelength We can see that absorbance and absorption spectrum are very similar same process Pigments are associated with proteins; they will modify absorption spectrum Protein = purifier Pigment=provider of E Evolution O2 Photo function = to reduce C by adding e (from H) When e are from water O2 involved Cyanobacteria, take e from other compounds no e involved 7 Begouen-BIOL205-Winter2015 7) Three phases of photosynthesis A) Photo physical phase: Light absorption and excitation transfer: ultrafast process : pico second 10^-12 = path excitation transfer B) Electrochemical phase: Electron transfer that allows NADP+NADPH and proton production to synthetise ATP <msec = path electron transfer C) Biochemical phase: C is captured and reduced < 1 sec = carbon path 8) Path excitation transfer Excitation energy transferred from 1 pigment molecule to another one in higher wavelength (lower quantum E) EX: carotene (450nm) chlorophyll b (650nm) Only works one way Lot is lost by fluorescence 9) Organization of photosynthetic machinery Evidence of 2 photosystem A) Transformation of 1 O2 requires 8 photons (instead of 4) B) Red drop phenomenon when go over 680nm , decrease in activity ( was one phenomenon that could only work before ) C) Emerson enhancement: when we have a whole light(= white light) it works 3 times better than separate extreme wavelength D) Discovery of cytochrome complex: taking electron from one side and being reduced while giving electron to other side and being oxidised (see BIOL 201) 10) 2 photosystems Are called photosystem 1 (700nm) and photosystem 2 (680nm) Each organized in group and with reaction centre and antenna pigments ( each associated with specific prot that give them special absorbance charact. 11) Organisation of 2 photosynthesis In a Z scheme Starts by system 2 (PS2) –excites itself with light, loses electron, E goes down , then system 1 (PS1) excites itself (incoming light) , E goes up, loses e , and finally oxidise NADP+ to NADPH Both system activities = synchronised 8 Begouen-BIOL205-Winter2015 To make up for electron loss, those remove from PS1 go to Fd and to cytochrome and then to PS1 ATP production 12) ATP synthesis Protons pumped in to thylakoids membrane Higher PH = less protons Light reaches chloro. Protons move from stroma (PH+) to lumen (PH-) (????) Experiment : Put chloro membrane in low PH buffer, PH+, transfer thylakoids to high PH+ Pi and ADP in dark , still gets ATP Protons transfer from stroma to lumen escape through ATP synthase, after every 3or 4, ATP made Product of light reactions D) NADPH H will be use to reduce carbon E) ATP E needed to do carbon reduction When organism take food from other organism, must break it bc : A) Food particle too big to enter cells B) Food entering was made according to other organism genetics Everything must be breaked down into monomers (so can use it) C) Digestion provides identity to what is being eaten, if not = allergy 9 Begouen-BIOL205-Winter2015 LECTURE 4- CARBON ASSIMILATION 1) Photosynthetic Carbon Reduction Cycle (PCR)=Calvin cycle Carbon reduction: 6CO2 + 12H2O Glucose + 6O2 + 6H2O + E (672kcal) Products of light reactions - Electrons from water - NADPH from NADP+: reduce carbon during carbon cycle - ATP from ADP + Pi: activates molecules of intermediates during Cavin Cycle To incorporate atmospheric CO2 acceptor molecule is needed. Calvin Looked for it Made up nobel-prize winning experiments: In a flat lollipop (where cells will get all light uniformly) ,we shine light for a sec , and then kill cell by putting them in boiling methanol no more reactions, we extract carbohydrate - Since CO2 was radioactive, whatever was produced thanks to it will be radioactive and we can find it Goal here = to find which molecule became radioactive first: it would be the acceptor. - Paper chromatography allows to find where are products - Radioactive shadow are noticed – to separate further, rotation of 90degrees - To know what are all the spots comparison with know elements ex: Sucrose First product made was PGA, a 3 C molecule. With time increasing different carbons of the PGA were labelled means there is a cycle. They then searched for a 2 C acceptor, but none was found CCL: A 5 C uses 2 CO2 to form PGA RuBP So PGA initial product and RuBP CO2 acceptor. Proof: - In absence of light: no ATP & NADH produced PGA is not metabolized into glyceride 3 phosphate , PGA accumulates . BUT CO2 is still here RuBP is still consumed - In absence of CO2 but with light , RuBP not used, accumulates BUT PGA is used, consumed as ATP and NADPH available from light reactions. PCR cycle 3 steps - Carboxylation - Carbon Reduction (ATP to ADP and NADPH to NADP+) - Regeneration of CO2 receptor (RuBP), phosphorylated with ATP to start agai 10 Begouen-BIOL205-Winter2015 Carboxylation ( of RubP ) Made by RUBISCO enzyme (bifunctional) = most abundant prot on planet catalyses first reaction in photosynthetic carbon assimilation Very large 8 large subunits + 8 smalls Has 2 functions=bifunctional: Adds CO2 or O2 to RuBP carboxylation or Oxygenation On carboxylation: unstable 6 C intermediate splits into two 3C of 3-PGA = first product of carboxylation. Calvin cycle C3 photosynthesis. ( in chloro) VS when CO2 fixed in cytoplasm to 4C compounds then transported to chloroplast C4. There are 2C fixations . Carbon Reduction : 3-PGA to 3-phosphoglycerade. Before reduction 3-PGA has to be activated by phosphorylation using ATP formation 1,3diPGA Reduction to G3P using NADPH. Product light reactions ( ATP and NADPH ) used in activation and reduction of 3-PGA Regeneration of CO2 acceptor : series of reaction. G3P and DHAP form 6C . Then combine 3C and 6C BLABLABLA pleins de molecules In the end Ru5pRuBp by ATP !! Must know where NAPH and ATP are used !! Photosynthetic product can be used for export and storage :DHAP goes out of chloro for other roles CCL : For each cycle : 3 ATP and 2 NADPH used 2) Photorespiration : Comes from oxygenase function of RUBISCO, add O2 to RuBP. During evolution, efficiency of carboxylation increased Since O2 much higher than CO2, oxygenation should be favoured over carboxyl BUT RUBISCO has greater affinity for CO2 than O2. One factor determining ratio = affinity of RUBISCO for 2 competing substrates : inverse mesure of this infinity = Km Lower Km = greater affinity !!To be active RUBISCO needs to bind to a CO2 !! Photorespiration occurs at cost of photosynthesis Phosphoglycolate is sent to peroxisome, is oxidized to glyoxylate using O2 Then glyoxylate amino acid glycine Glycine mithochondrion release amino group. Sent back to peroxisome where is used to convert glyoxylate to glycine . 11 Begouen-BIOL205-Winter2015 Phospho decrease efficiency of photosynthesis. Location : depends on what kind of plant it is. 3) CO2 concentrating mechanisms: C4 plants 2 experiments found out that in C4 plants (corn and sugarcane) 1st products wasn’t PGA BUT C4 acid : MALIC & ASPARTATE acid C3 plants first product = PGA To limit or decrease photorespiration : Increase CO2 concentration around RUBISCO C4 plants actually did so CO2 fixed in cytoplasm of mesophyll cells MalateBundle sheath burst CO2 Chloroplast carry out rubsco’s fixation of CO2 Products move through plasmodesmata C4 Concentrate CO2 at carboxylation site in BSC chloro’s stroma - Co2 first fixed in MC cyto ( Comes from atmosphere directly into) - Malate transported to BSC cell ,thanks to Malic enzyme NADP+ is oxydise Calvin cycle - Pyruvate comes back to Mc CAM plants (Cacti) - Same reaction as C4 - One occurs during night and other during day - Do not open stomates during day – only in night in order not to lost H20 CO2 comes in, Malic made and stored in Vacuole , SUUUUper high C - During day Malic is decarboxylated Calvin cycle Difference between C4 and CAM - C4 happens simultaneously in different set of plant - CAM has a separation in time 6)Differences between C3 et C4 plants C3 much lower Co2 concentration than C4 through stomata from atmosphere Light compendation point (LCP) and CO2 compensation point (CCP) We need a CCP higher then LCP to have photosynthesis C3 - CCP from 50 to 100 ppm Co2 C4 CCP 0-5 ppm (everything released is fixed right away ) CAM 0ppm FINISH ENDING 12 Begouen-BIOL205-Winter2015 LECTURE 5: WHOLE PLANT AND CROP PHOTOSYNTHESIS. 1) Response of photosynthesis to light intensity Minimum light intensity at photosynthetic carbon gain= carbon loss due to respiration/photorespiration Light compensation point (LCP) Under LCP: plants are loosing C will exhaust themselves to death through respi. At LCP: Zero net photosynthesis Over LCP: light intensity is so high that products (ATP and NADPH) not consumed fast enough by Calvin cycle. Photo oxidation and photo-inhibition of photosynthesis [ damage to photosynthetic machinery depending on excessive light intensity level). Photo inhibition under moderate light excess = dynamic photo inhibition. Rate of photosynthesis Will slowly reach rate of optimal photosynthesis. Whether plant = sun plant or shade plant can be acclimatized to diff light intensity. Plant used to a low light I will reach stop at photosynthetic rate before plant used to a higher light intensity Even if Sun plant, response to light I depends on previous exposure Sun and shade plant differ in response to light I shade plants’ photosynthetic rate saturated lot earlier. Plant Have avoidance/ tracking mechanism to regulate light’s absorbance. If light to high, Chloro will hide behind each other to avoid excess light Some plants follow sun in other to receive optimal light Some plants evolved to be shade-plants(shade love) or sun plants (sun loving) 2) Response of photosynthesis to CO2 !! Right now, CO2 in atmosphere 350 ppm!! Increase CO2 associated with climate change. HOWEVER minimum CO2 concentration required for plant survival. Concentration of CO2 at which C gain = C loss no net photosynthesis = CO2 compensation point (CCP) CCP in C3 plants 50-100ppm CCP in C4 plants 5-10 ppm CCP in CAM plants 0 100% CO2 released by respiration = refixed by photosynthesis Increase in CO2 concentration accompanied by increase in C assimilation This increase more pronounced in C4 than C3 13 Begouen-BIOL205-Winter2015 Further increase in CO2 does not increase rate in C4 C4 photosynthesis limited by light I not CO2 concentration. In C3 increase in CO2 concentration diminishes photorespiration but keeps increasing photosynthetic rate 3) Response of photosynthesis to Temperature Rate of photosynthesis = constant between 12C and 37C in C4 plants C3 decline in photosynthetic with increased T (between 14C and 40C) Photorespiration more responsive to T increase than photosynthesis decline in C3 photosynthesis due to larger increase in photorespiration than photosynthesis. 4) Response of photosynthesis to O2 Photo respiration occurs due to RUBISCO bi-function and because there is a higher O2 concentration than CO2 decrease in photoresp expected to increase photosynthesis. C3 higher vegetative growth at reduced O2 decrease in photorespiration can increase vegetative growth C4 no change Results on reproductive growth In both C3 and C4 decrease in reproductive growth as O2 concentration is reduced. Production of seed requires O2 concentration. But why does fruit/seed development requires so much O2 reproductive dev has intensive E requires intense respiration that only O2 concentration can support. 5) Plant architecture and productivity Most important morpho feature (determine dry matter production) Leaf angle Can modulate angle of shading of lower leaves by upper ones Amount light interception photosynthesis= different in upper and lower leaves Crop yield varies with leaf angle Highest yield = reached when angle = close to 90 degrees There has been computer simulation to see yield of leaves at diff angles. When top leaves = horizontal and lower leaves vertical extremely low When top leaves =vertical and lower = horizontal high Leaf angle can have important application for community level of crop yield Ex: if a crop = vertical leaves can have more plants per unit ground area Since crop iels depends on planting density higher D = higher yield 14 Begouen-BIOL205-Winter2015 6) Community level determinants of crop yield 2 important community level determinant of crop yield Leaf Area Index (LAI) and planting density. LAI = ratio between total leaf surface and ground surface under leave dimensionless can determine prod/plant/unit area Increase during crop growth until reach final size = related to dry matter accumulation Plant density =number of plants per unit ground surface In agriculture controlled by seeding rate will depend on % germination of seeds ( rarely 100%) If %= low , higher seeding rate has to be used. Farmers in ancient Egypt had figured out optimal seeding rate by trials and errors Mathematical relation between density (d) weight per plant (w) and yield (y) Y=w*d !!!+ see equation in book for dry weight !!! y =density dependant young crop = small and far apart , Mature stage plant are shading each other Growth of one plants affected by its neighbour. Y becomes density-independent bc increase number of plant =decrease in weight per plant (effect=0) LAI increase with crop growth. LAI can be substituted for density to determine effect on weight and yield RESEE THIS PART 7) Efficiency of energy conversion At the level of carboxylation to fix 6CO2/make one glucose/evolve 6O2 minimum of 48 (6*8) photons of 680 nm = required. !! = minimum, can have more (10 or 12 photons) Input of E = 8640 KJ Output (E stored in one glucose)=2872 KJ Efficiency = 33% (max) Efficiency of E conversion by a leaf 40% of Sun E is absorbable. 8% of it lost through transmission/reflection 8% of it heat dissipation 15 Begouen-BIOL205-Winter2015 19% in metabolism 5% of total can be converted to carbohydrate 8) Annual budget of a tree Gross photosynthesis/ shoot respiration/root respiration will vary according to day time or time of the year Low rate of metabolism in winter (C loss under the snow ) Needles respiration during night has to be subtracted to photosynthesis stuff Annual CO2 balance for pine: 5283.3 mg 16 Begouen-BIOL205-Winter2015 LECTURE 6: CAPTURE, INGESTION, DIGESTION AND ABSORPTION OF FOOD IN ANIMALS 1) Nutritional requirements obtained from food All animal obtain food by eating plants (directly) or by eating animals who ate plants (indirect) complex food requirements Types of food components obtained by animals: - aa build proteins. Obtained during digestion - Simple sugars (Glucose) used to obtain E or to store it as glycogen. Also needed to synthetize other molecules - Lipids synthetize cellular membrane or source of metabolic E - Inorganics salts synthesis of nucleic acids + osmoregulation - Vitamins to assure normal function - Water essential solvent. Not every chem element = essential in animal nutrition. Biological evolution= continuity of chemical evolution certain chem elements were selected to build up prebiotics systems and biological systems were built from it. Animals require them in various proportions Some can be needed to some species and not to others. Essential nutrients = nutrients that cannot be produced by the organism Vitamins and some aa. 2) Feeding methods Unicellular organism take up food by surface absorption food has to be in molecular form. Is produced by death and decay of other life form. Unicellular fed by endocytosis. If food taken in solid = phagocytosis If food is dissolved =pinocytosis Multicellular capture food in specific ways -Tentacles -Sucking -Tear Feeding methods of bird have to overcome certain difficulties: refractive indice of water (apparent position of prey is not the real one) + movement of the prey. Possible neuro mechanisms 17 Begouen-BIOL205-Winter2015 3) Digestive system Digestive system structural organs providing contained space for digestion + accessory digestive system secreting enzymes Some animals: Secluded groove long tube track opened at ends (one for ingestion and the other one for expulsion of undigested stuff) Those grooves not internal to organism. Food lies outside body of organism. Tube like structure called digestive track/alimentary canal/gastrointestinal tract/ gut Tube like nature Efficient design different regions of the tubes can be modified to carry out temporal sequence of digestive steps as food passes through. Digestive system digestive track +glands (putting biochemical digestive fluids) in gut. Throughout length of alimentary canal cells secrete mucus that facilitate food movement Vertebrate alimentary canal regions : Head gut mouth part of the gut serves to detect/ingest and breakdown food into smaller parts . Process increase total surface area of food particle rapid enzyme action. In first part of it (mouth) : Saliva+mucus secreted . Mucus wets food for easy handling Saliva has bicarbonate and amylase that degrades enzymes. Digestion starts with mouth chewing Foregut includes esophagus ( part of it can become crop in some invertebrates + grain eating and fish-eating birds have a large one for storage ) Midgut stomach and small intestine. Part where both absorption and digestion happen. In stomach cells secrete hydrochloric acid into lumen activates digestive enzymes Small intestine digestion of prot = completed & digestion of fats and digestion of carbohydrate continues . Acidity from Stomach=neutralized Absorption of products from digestion takes place in small intestine Hindgut Large intestine. Absorption of materials and water takes place before undigested materials is expelled. Contains microbial community to try and digest cellulose and vitamins. 4) Digestion =Biochemical process by which macromolecules monomers constituents Different parts of alimentary tract digest diff components of food. Nature of digestive enzyme varies with part of digestive track. 18 Begouen-BIOL205-Winter2015 Mouth food physically broken into pieces to increase action area of enzymes . Mouth several pairs of salivary glands that will secrete saliva ( with amylases – starch degrading enzymes) Saliva has 3 functions : - Moisten food for easy chewing/swallowing - Acts as solvent for food molecules bind to taste bud, facilitates perception of taste - Contains amylase degrade starch into glucose Also contains bicarbonate ions neutralize acids in foods. In insectsenzyme invertase that breaks down sucrose. In some animals saliva has special functions (contains poisons and toxins and anticoagulant) Every day production of 1L of saliva. Oesophagus Muscular tube with sphincter at each end. Food enters it as soon as swallowed (is all or none reflex) Food =prevented from entering into nasal/trachea passages or re-entering mouth Digestive process from mouth continues in oesophagus. Cells on walls secrete mucus that helps passage. Sphincter (band of muscle tissue) controls passage from oesophagus to stomach Stomach As food enters carbohydrate digestions continues. Cells in stomach lining contains hydrochloric acid+pepsinogen + gastric juice (contains intrinsic factor (essential for B12 vitamin )) . HCl in stomach lining converts pepsinogen to pepsin (active form) Up to 3L of gastric juices produced daily, its pH=1,5=strong enough to kill a bacteria Small intestine Partially digested food stomachsmall intestine First u-shapped part= duodenum. Specialized cells in it secrete enzyme that participate in digestion/ activate other digestive enzyme 2 types of digestive secretions poured in : - Pancreas secretes pancreatic juice by pancreatic duct. Contains unprocessed form of prot degrading enzymes. (Contains lipase, amylase, nuclease, maltase ) +Bicarbonate - Bile brought in by bile-duct. Produced by liver , store in bile gladder has bile fats (essential for fat digestion) Digestion of all fats primarly in small intestine pH=7 to 8 Large intestine Digestion is already complete large intestine will maintain water and ionic balance . Absorbs water & ion from undigested material before expelled by defecation Total length of gut reflects digestibility of food that animal eats. Herbivore’s food takes longer to be digested than carnivore’s Total length gut greater in herbivore. Within particular group (bird) length related to type of food eaten Called Eco morphology Gut also contains ++ organisms: archae, bacteria, fungi, parasitic worms … play essential role in digestion= Mutualistic relation (both benefit) 19 Begouen-BIOL205-Winter2015 Their role particularly important in herbivore bc cannot degrade cellulose ( that is major part of plant material) Some of the micro organisms produce cellulose and will help org to degrade cellulose to glucose. Can also produce Vitamins Evolutionary conflict between organisms & food some plants now have defense mechanisms Ex : tannins 5) Chemical reactor theory Digestion system can be compared to a reactor (series of bulk reactions where reactant and catalyst mixed and products removed according to time) Food and enzymes mixed together and product = removed through absorption Reactor will influence production efficiency: size/shape/patterns 3 types of reactors - Batch: Single vessel Put reactants and catalyst in reactors(= enzymes, substrates) , mix it , let it go then empty it and extract product from content ( input and output from same entrance). Efficiency will depend on time, the longer the reactants are in , the more products we get. Ex: Hydra. Lost time in emptying and refilling - Continuous flow stirred (CSTR) 2 openings, one for input, one for output continuous mixing : rate digestion = rate absorption. Global rate depends on size input/output. Good for animal that graze for long periods. Ex: Camel. = Progressive digestion - Plus flow reactors (PFR) Shaped like a long tube. Continuous input, move through long tube and enzymes are being added at certain places progressive digestion. Mixing occurs only across radius, not length. Product removed along the way. 6) Structure and function of the herbivore gut Cell wall = 30-55% plant tissue dry weight mainly cellulose. None of constituents soluble in water. To digest cellulose need help of microorganisms. Also carry out food fermentation. To pass over that, some herbivores have multi chamber stomach slow process of digestion w/ repetition of certain steps Ruminants – regurgitate and re-chew food from stomach chamber: reticulum. To get sufficient return from slow digestion increased stomach size Small herbivore feed on high Q, young plant tissue vs large herbivore feed non-selectively (have to eat more thus larger stomach) Ruminant stomach = digastric stomach 20 Begouen-BIOL205-Winter2015 1st part Rumen and reticulum 2nd part Omasum and abomasum Have rich microbial population During grazing animal eat as much as thyey can . Rumination happens when animal = resting partially fermented food in rumen brought back to mouth and re-chewed and swallowed again in Rumen (got broken in smaller pieces facilitates digestion &fermentation more ) Large amount of CO2 and methane CH4 are released. Expelled by burping Dietary fiber cellulose and else presence is important for health because of dietary fiber 7) Absorption of digested food Small intestine where major absorption occurs BUT water and ions Large intestine To maximise absorption: surface area increased in small intestine . Epithelial cell organised into villi. Tightly organised Most epithelial cells = absorptive but some = goblet cells and secrete mucus . Food molecules absorbed passed to bold and lymph vessel other part of body Nature of stored food reserve glycogen. Used as substrate to respiration ,growth/repair. Equivalent in plant = starch 8) Digestion in insectivorous and carnivorous plants Insectivorous plants digestive juice similar to animals’. Pitcher like a toilet, prey tries to lich nectar, falls into pitcher Might be response to nitrogen-poor soil. Animal = protein supplement 9) Feeding the young Mammals & birds produce milk. Concentrations of constituents in milk vary . Protein concentration related to growth. Penguins male eats nothing for 2 month, is female doesn’t come back starts producing milk 10) Coprophagy Since plant material = hard to digest Small herbivore expel partially digested food through defecation and eat it to take remaining nutrients in it. Ex: Rabbits 2 types of feces: small and hard: low N = bad VS softer high N consumed and digested further !!! Re-ingested food not mixed with previous one, kept t the end of stomach !!! 21 Begouen-BIOL205-Winter2015 11) Evolutionary and ecological aspects of digestive systems of animals All animals consume food conflict between animal and food Plant evolved mechanisms to defend themselves thorns, unpleasant coating /poison Almost all wounding response = produce signal (jasmonic+salicylic acid) , will enter atmosphere and produce inhibitors in their leaves . Very effective against insects, not so sure about large herbivore Total length digestive track = longer in herbi than carni we can guess nature of diet by looking at digestive track length ecomorphology During rumination large amount of CO2 and CH4 produced. CH4 has hydrogen (product of photosynthesis ) Loss of methane = loss of 12% of E from ingested food . Also cause global warming (3% of all global warming gases) 22 Begouen-BIOL205-Winter2015 LECTURE 7: AEROBIC AND ANAEROBIC E PRODUCTION 1) Nature of stored food Hexoses (6C sugar) primary sugar product of photosynthesis. Not stored as food material Energy reserve = polymerized forms of glucose glycogen and starch Are macromolecules not subject to usual metabolism. Long term planning need good reserve large macromolecule Under extreme starvation fats and protein used for E production Respiration = reversal of carbon reduction during photosynthesis Photosynthesis glucose produced from water & CO2 & O2 evolved. Input of 686 Kcal Respiration glucose oxidized to CO2 &water & H2O produced. 686 Kcal released and packaged into ATP or heat. Reaction = opposite of photosynthesis 2) Mobilization of stored food and glycolysis. Starch/glycogen glucose before, later used as substrate for respiration. Happens 2 ways: - Glycogen/startch glucose 1P by phosphorylase. - Glycogen/startch glucose glucose 1P with 1 ATP Glycolysis Glucose 1P enters series of reaction constituting glycolysis , no need for oxygen Production of 2NADH and 2ATP for each glucose consumed If glycolglucose (1 step) production of 3 ATP End product (for 1 glucose consumed) = 2 pyruvates energy rich molecule. 3) Fate of pyruvate when O2 available: TCA cycle (Krebs) No O2 consumption during glycolysis but AFTER, fate of glycolysis depends on if there is O2 If O2 : pyruvate goes to mitochondria , gets decarboxylated (looses CO2) CoA enters Krebs cycle there is progressive decarboxylation released H used to reduce NAD+ & FAD to NADH and FADH2 Removal of 3CO2 = breakdown of 1 molecule of pyruvate there is also production of GTP/ATP 4) Oxidation of NADH/FADH2 + synthesis of ATP e from NADH/FADH2 oxidation enter electron transport chain = 4 complexes of electron carriers, are in mitochondrion. + in the end enter ATP synthase O2 = terminal electron acceptor, will form water ( proof that aerobic organisms need O2) 23 Begouen-BIOL205-Winter2015 . During same time ATP made and released into matrix. See BIOL 201 Differences between plant and animal transport chain : Plant 2 additional NADH dehydrogenase( one on each membrane ) + alternate oxidase (e skips complex 3) = big O2 consumption and little ATP made=alternate respiration ( generates heat ) prevents e- flow from complex 2 to complex 3 and further downstream. Signal to change from one pathway to another = salicylic acid Various chemical : can interrupt electron flow at several diff steps. DNP makes inner membrane leaky prevents built up of proton concentration and motive force ( Driving force of ATP synthesis ) 5) Fate of pyruvate in O2 deficient conditions ( Hypoxia or Anoxia ) and fermentation Glycolysis = important because even if org produces little ATP, can’t survive without oxygen To glycolysis to occur, constant NAD+ needed. Need of a mechanism to consumed NADH produced in glycolysis ( to regenerate NAD+ ) In animal Lactic acid fermentation pathway !! Fermentation: pyruvate lactic acid by lactate dehydrogenase. Consumes NADH and produces NAD+ Explains why rate of glycolysis increase during exercise when O2 supplies lie behind O2 consumption glycolysis becomes predominant for ATP production Lactic acid (lactate) metabolized as exercise ceases conversion to glycogen in muscle or send to liver where conversion to glucose ( Cori cycle ) Plants = important diff in anaerobic pyruvate metabolism : lactic acid fermentation = only transient mechanism Production of ethanol !! Gluconeogenesis : Other way to remove pyruvate so glycolysis can keep going) . Close to reverse reaction of glycolysis regenerates glucose. Occurs during germination of oil seeds 6) Respiratory quotient and respiratory substrates ( other than carbohydrates ) Respiratory quitient = RQ RQ = Volume CO2 produced/Volume CO2 consumed Value Depends upon substrate nature Ex: In glucose RQ=1 24 Begouen-BIOL205-Winter2015 Fats More CO2 consumption than CO@ production RQ=0.7 When starvation protein used as respiratory substrate RQ=0.8 Temperature = effect on RQ ( because depending on T, organism are going to use different type of substrate ) At low T = fats = low RQ vs higher T=carbohydrates = high RQ !!! Reminder stored food must be breaked from macromolecules to monomer and converted to glucose and pyruvate before being used as respiratory substrate !! 7) How much E is produced during respiration? = how much ATP produced during anaerobic and aerobic respiration glycolysis : net prod of 2ATP One round of Krebs cycle 3C pyruvate = oxidised to CO2 and we get those products 3CO2 4NADH 1FADH2 1ATP/GTP for animals And one glucose 2 pyruvates Twice those products During e- transportation, proton motive force drives ATP synthesis. And since NADH contributes to proton motive force, each NADH = 3 ATP and FADH2 = 2ATP Therefore total ATP production , for 1 Glucose ( =2 pyru) 24ATP (from 8NADH) 4 ATP ( 2 FADH2 ) 2ATP/GDP 30 ATP molecules per Krebs cycle + 2 produced during Glycolisis TOTAL = 32 ATP Also if 2 NADH from glycolysis enter mithocondria, ( not necessary) 6 more ATP produced MAX = 38 ATP If anaerobic respiration , only ATP = from glycolysis ( NADH used to do NAD+ in order to keep glycolysis going) 2 ATP = organism barely survives 8) Efficiency of respiration Glucose = 686Kcal 36 ATP= 270 Kcal Efficiency of respiration = 39 % 25 Begouen-BIOL205-Winter2015 Rest of E = heat In plant, heat produced is NOT captures = released 9) Heat production during respiration Part of E liberated = in form of heat. Amount of E produced/gr food Depends on food type (Fats, prot, Carbo … ) SEE table Heat liberated = used to maintain body T In migration animals ( birds) easier to carry fats over carbohydrates over long flights because less heavy 1Kcal of E = 1gr Glycogen = 0.11 gr of fat !! Glycogen can be mobilised very quickly and in anaerobic conditions (NOT fat) !! 10) Role of E produced by respiration Part of E produced --> maintenance +repair of cell/tissue = continuous process : In early growth , large part of E was used for growth (new cell/tissue) . After reaching optimal size growth requirements decrease maintrnance becomes predominant 11) Role of respiratory intermediate Glycolysis + TCA cycle many intermediate : diverted in cellular constituents. Ex: Glucose 6P synthesize Glucose for wall assembly Glycerol from 3-PGA ( glycolysis) synthesize triglycerides and phospholipids Acteyl CoA Fatty acids ( and = precursor of some pigments ) 26 Begouen-BIOL205-Winter2015 LECTURE 8: METABOLIC RATE, SIZE AND ACTIVITY 1) Metabolism Metabolism = total sum of synthesis process and breakdown process Anabolism (make complex from simple), will store E =growth & Catabolism ( Break complex in simple ) = release of E Some E ingested won’t be harvested thrown out = fecal lost ( = undigested and unabsorbed) Other part = absorbed metabolizable E Different functions: prod of new tissues : can be structures that will be lost ( nails, hair) or gametes Digestion & synthesis have a cost (empty stomach = cold, one in digestion =Warm = cost ) E released during respiration = proportional to intensity of activity To measure rate of activity use : measure O2 consumption and CO2 prod. All of those produce heat ( transfo E ) Leftover E will be used for growth. More E taken in than used All E = reducible to heat. Metabolic rate = rate of E released through respiration ( Cal , Joules or Watts) is measured as 02 consumption (limit is that doesn’t take into account anabolic systems) Need conversion from one to other 1 ml O2 = 4.8 Cal 1 L O2/hour = 5.58 Watt Energy budget animal = impact on biosphere : CH4 in ruminants contribute to warming 2) Metabolic rate: Measurements E = produced by breakdown of food reserve during respiration (with O2 consumption) Metabolic rate can be measured by finding out : heat content of food consumed OR rate of O2 consumption Several Methods: - Direct calorimetry : Sensitive calorimeter used to measure anount heat produced by animal/unit time : Insulated container of know mass of water where heat from animal goes and raises the T - Indirect calorimetry : Measuring each component of Organism’s energy budget. - Respirometry : Most commonly used method. Meadures O2 consuption or CO2 prod Based on know relationship between the 2. Complication = nature of respiratory substrate ( only carbohydrate RQ is 1 , other don’t work , CF lecture 7) 27 Begouen-BIOL205-Winter2015 Place animal in respirometer (close chamber ) with inlet and outlet , diff in concentration = amount of O2 or CO2 produced or consumed - Double labeled water method: only method that can be used in natural habitats : good for field ecologists ; Animal is captured and injected with marked water ( isotopes) , blood sample is taken and animal released Since water is lost throught secretion and evaporation concentration of labeled isotopes declined ( O2 faster than H ) Difference between those 2 = amount of CO2 lost = Measure of metabolism Basal metabolic rate (BMR) Only endothermic animal = 02 consumption by animals. Measured when animal resting AND NOT digesting, at intermediate T Standard metabolic rate (SMR) Only in cold-blooded animals (ectothermic). Measured when resting and not digesting. Diff no heat production (need less food) , animal must have been at medium T for a long time Field Metabolic rate (FMR) Metabolic rate measured in field with doubly labeled water technique Hydrogen is measured (by radioactivity). Determination of BMR and SMR Measured with 02 3) Body size and metabolic rate at whole organism level Larger organisms : consume more O2 Increase in size = increase in volume BUT gaseous exchanges : occur at surface in contact with enviro Surface increase to the square and volume to the cube surface proportional to V^2/3 Lagging behind of surface area : great effect on metabolic rate of whole body. Is noticeable in MSMR ( Mass specific metabolic rate ) If we plot them straight curve with a 0.67 slope =isometric relation If MSMR was a line with a 1.0 slope isometric relation. If not = Allometric MSMR declines with body-size : -0.25 slope = Allometric MR = aM^b Mr = metabolic rate A= proportionality coeff M= body mass B= Power function At whole body level, by unit of body mass , big animal consume less O2 Metabolic rate endotherm = higher than ectotherm Mutlicell = higher MSMR than unicell 28 Begouen-BIOL205-Winter2015 4) Body size and tissue metabolic rate But what about organs ? ( Where is MSMR reduction occurring ) Group of 5 kg organs ¾ of whole body mechanism = Heat, kidney,brain, lungs + splanchnic organs Some organs = metabolically more active Muscles = 40 % body mass Metabolic rate at whole body level =90.6 Watts Decrease level = located everywhere, in organs, metabolic rate decline with increase in body mass. But is different in the different organs (brain = ½, liver =1/4 ) Same can be said with the tissues. Cell size does not differ much What is the basis of the MSMR reduction ? Lower mithochondria /cell in larger animals ( and it is where there is O2 consumption ) Number of e transport chain (in mithochondrion ) depends on surface area, if mitho has higher density of chain , will consume O2 with higher rate 5) Metabolic rate and activity Increase in activity = increase in metabolic rate ( at org level & per unit of mass ) Running : The smaller the animal, the higher the MSMR + MSMR increases linearly with speed ( this increase is higher for smaller animal than for larger one ) Also, small organism will have a greater cost for locomotion. Follows a line May be due to smaller animal having a lower efficiency of muscle contracting at higher speed. At one point , with speed increase MSMR won’t increase linearly with it Oxygen supplies will start lagging behind oxygen need. Ectoterms have a lower locomotion cost than endotherms. Net cost will rise with speed up to a limit speed increase beyond that limit won’t increase MSMR reached maximum aerobic speed ( MAS) When at speed over MAS, additional E comes from anaerobic mechanisms ( lactic fermentation) MAS cold lizard<warm lizard< mammals Mammals are able to move rapidly and for a long time but need to pay additional E cost for this capacity 29 Begouen-BIOL205-Winter2015 Some animals several modes/gaits of locomotion , will pick the most economical for the speed they want to go. Ex : horse. Total cost of locomotion /unit distance declines with speed increase. Swimming and flying, since occur through fluids,consequences more pronounced. Net cost of swimming increases with speed. But is not linear and increases a lot more rapidly than running Maximum range speed = higher speed for minimum cost of locomotion. animals use it to cover long distances like for feeding or migration. Flying : U shape curve : Low speed ( Hovering) and high speed are very E costly. Lack of forward momemtum results in higher cost of E to support body weight. Lower E costing speed = Minimum power speed. !!! Is not equal to maximum range speed!! If compare all 3 running most expensive swimming less In each one: Net metabolic cost declines with body size. MSMR increases with speed (more steeply in smaller than in larger vertebrates) LECTURE 9: METABOLIC RATE AND T 1) Effect of T on rate of Biological reactions. T = reflect of thermal motions of atoms and molecules Indeed, some reactions need a certain E to happen. T increase = E increase (because kinetics) Since chemical E depends on kinetic E, increase T increase chem E (exponentially) Q10 = concept that tells us how reaction react (number time it increases )with a 10 degree raise Measure number of time by which rate increase by every 10c Q10=Metabolic rate at T+10/meta rate at T we have to measure rate at 2 diff rate Increase of exactly 20degrees = limitation Solution : longer equation (see booklet ) that way, we can calculate Q10 no matter what T increase we get = logarithm equation Described by this equation : Y=b*a^x Y=rate at higher T b=rate at lower T a=Q10 30 Begouen-BIOL205-Winter2015 x=diff between 2 T /10 Can be re-written in the logarithm form : LogR2= LogR1 + LogQ10*(T2-T1)/10 With R the reaction rate. Value of Q10 decreases with higher T Normally, for most chemical, biochemical and metabolic rate, Q10 value =2-3 Some reactions, don’t depend on T: photophysical q10 =1 . They are temperature independent. If physical effect were T dependant we couldn’t see well when T goes down (pigments need light = E ) Enzyme catalyzed reactions. Metabolism= sum of all biochemical reactions in an organism. Increase in body T should be expected to be accompanied by increase in metabolic rate (We can see it by increase in O2 consumption) BUT is not totally true, biochem reactions catalyzed by enzymes. Each of them optimal T for maximum activity (T will change enzyme confo). how a T change affects rate of enzymatic reaction depends on optimum T for that enzyme After reaching optimum T and going over it , enzyme will get denaturised and wont work anymore : Functional tertiary structure becomes unstable. The greater the deviation, the faster the degradation. Important parameter for efficiency of enzyme = binding affinity (Km) to substrate. Km = concentration of substrate at which half-max velocity of reaction is reached. Lower Km = more efficient enzyme At optimum T , Km is the lowest. Some animal regulate body T endotherms = human = regulators Some organism no ectotherms ( lizards ) =conformers Small birds metabolic very active , have eat all time little time to rest. During might will lessen T so metabolic goes low and don’t have to eat goes blue 2) Effect of T on cell structure T affects metabolism by bringing change in membrane viscocity. Viscocity depends on how tightly packed are phospholipid . And packaging order depends on how mamy double bounds fatty acids tail have, Double bound = unsaturated Less packed =Fluid Simple bound = saturated = tightly packed =Viscous T direct effect on viscosity/fluidity 31 Begouen-BIOL205-Winter2015 Increase T Increase Fluidity = less rigid Lower T increase Viscosity = flexible. Mechanism evolved to compensate mechanisms of acclimation/acclimatization Specific enzyme will introduce the double bound in fatty acid 3) Effects of T on metabolic rate Endotherms have thermo-neutral zones where even if outside increase, metabolic rate and body T remain constant. MSMR increase exponentially with T 4) Acclimation and Acclimatization Acclimatization = induction of tolerance to otherwise lethal degree of stress by being previously exposed to a non-lethal degree of stress. Capacity to acclimate = genotype dependant Acclimation : carried under laboratory experience Acclimatization : occurs in nature !! Not to be mixed with adaptation, adaptation = evolutionary process!! After full acclimation rate of metabolic will reach same as if in normal conditions Effect of acclimation on metabolic rate occurs at level of individual processes. Protein synthesis = central metabolic process machinery protein synthesis have to acclimate in order for whole plant to acclimate. The longer the acclimation period the better the survival. Physiological mechanisms How come after long enough acclimation, cells synthetize protein at same rate at 4 and at 20c If whole mechanisms is indeed going slower, just have more stuff taking part into it lot more ribosomes, mRNAs + other mechanism underlying processes of acclimation and acclimatization New forms of enzymes produced that are more efficient fatty acid desaturates induced , will induce double bounds in fatty acids preventing membrane from being too rigid. Under high T double bounds removed to make membranes less fluids to avoid them to melt away at high T Acclimation requires O2 availability At least in animals, acclimation only occurs when there is no O2 availability Acclimation involve active + E-requiring steps. 32 Begouen-BIOL205-Winter2015 LECTURE 10: CELL WATER RELATIONS AND UPTAKE OF WATER 1) Properties of water Largest constituent of living system: 70-95% organism fresh weight ideal fluid = stable Great force of cohesion between molecules Universal solvent bc great dipole property when added to solute, will dissolve electrostatically combined ions. Ex: will separate NaCl into Na+ & ClDipole property = due to partial charges on its components atoms. Can insert themselves between diff atoms. high heat capacity may capture heat but T won’t rise. high latent heat of vaporization Transparent to visible radiation All lands plants take up water from soil BUT 99% water taken by land plant returns to atmosphere through transpiration. 2) Forces driving water movement During movement work is done Force is involved Water will move according to chemical potential: From higher chemical potential to a lower one, will be spontaneous. Work done =Fdx With x the distance And force = F F= (difference in water potential)/distance derive Movement of water between 2 systems is determined by difference in their chem potentials. Water potential = chemical potential/ partial molal volume of water driving Force for water movement will move from higher W to lower W follows negative water gradient < or = 0 Water potential = composite force resultant of several component force : - Gravitational potential=Wg= Due to weight. Major part in ascent of Xylem in tall trees - Matric potential = Wsigma= Colloidal substance can absorb large number water molecule. Decreases tendency to move < or = 0. Major part of water movement within soil. 33 Begouen-BIOL205-Winter2015 - Pressure potential =Wp= hydrostatic/turgor pressure. Will be > or = 0. Increases tendency of water to move. Osmotic potential ( Solute potential) = Wpi= due to presence of solutes. Reduces tendency of water to move ( water molecule form shells around solutes) < or = 0. Only happens when we have semi-permeable membrane We don’t consider gravitational and matric potentials at cellular level W=Wp+Wpi Highest value of W = pure water = 0 3) Pressure-driven bulk flow of water over distance Another process by which water move= Bulk flow = mass concerted movement of molecules in response to pressure gradient. Ex: Flow of river, falling rain, water movement through a hose. Rate of volume flows depends on the tube radius, liquid viscosity and pressure gradiant that drives the flow Volume flow rate = IN THE BOOK Doubling radius of tube Increase volume flow rate by a ratio of 16 (2^4) Such pressure-driven bulk flow of water is the predominant mechanism for water movement for xylem from roots to leaves. 4) Diffusion and Osmosis and Molecular mechanisms involved in water movement. Molecule Have inherent thermal E Leads to diffusion (random mov) Molecule tends to spread in all directions. Will spread in all directions from regions of high concentration to regions of low concentration. If during this movement encounter semi-permeable membranes = asymmetric distribution of solute on both side rise to osmotic potential Movement of water facilitated by pressure will overcome molecular kinetic motion Unidirectional flow from high pressure to low pressure Allows for pressure-driven bulkflow over long distances. Diffusion : un-facilitated movement of a substance due to inherent kinetic/thermal E. Is completely random. As long as no other force: down concentration gradient. Cannot account for transport through large distance Osmosis : Diffusion substance through selective membrane. Water passes but not solute. Water moves from higher to lower C. Driving force = difference in water pot. 34 Begouen-BIOL205-Winter2015 Water potential = measure of un-satiated thirst. For short distance, we ignore role played by gravity and matric potential. Within soil matric potential plays determining role. 5) Pathway of water movement and operational forces. Movement of water within soil over short distances. In soil, water moves as bulk flow (solutes move with it, no membrane Wpi=0) Also = open system no pressure potential Wp= 0 W=Wsigma =Matric potential. Soil solution moves through root intercellular space up to endodermis solution reaches outside endodermis without encountering any membrane. Endodermal cells have casparian strips they force water to enter endodermal cells Then since we have membrane, osmotic potential (Wpi) comes into play. Movement of water from outside endodermis to Xylem vessels Movement of water determined by difference in water potential between origin and destination. (Destination < Origin) Water and dissolved mineral content move through free space between cells at epidermis and cortex. Water potential in soil = Sum (osmotic and matric) potential. Water potential in Xylem Vessel = Sum (osmotic and pressure) potential Once water enters xylem vessels goes upward and escapes to transpiration 6) Determination of Water potential, Osmotic potential, Pressure potential. Do determine Water potential Water flux equilibrium methods (tissue slices) - Cut tissue and determine weight Place them in different solution concentration Determine final weight Plot the initial/final weight ratio against manitol concentration Find solution C where there is no change in weight = 1 ratio Since no Wp (open system) W = Wpi More accurate way = use of a psychrometer to determine water/osmotic potential. Chamber with junction between 2 diff metal wires. Change in T at the junction generates current in wires, that can be read. 35 Begouen-BIOL205-Winter2015 Water of know potential with drop + vapour. If have the same water potential not net movement of water vapour. Determination of Osmotic potential by depression of freezing point method. Tissue is crushed and thermometer inserted. Latter is allowed to freeze. We note T when freezing occurs. By applying equation, we can calculate osmotic potential 1 molal solution decreases freezing point by 1.86 C By knowing the water freezing point we can determine the concentration of solution Determination of Pressure potential Is the most difficult to measure 2 methods : - Manometric method (micropipette ) : Pressure pot = measure of cell turgidity Micropipette with known volume touches water surface capillary rise Inserted in cell cacuole . Vacuole sap will go in micro pipette as aur rushes in pressure gauge . As sap comes in , air inside is squeezed into smaller space Note final volume and since P1V1=P2V2 Can get final pressure = Wp - Scholander’s Pressure bomb technique: Twig inserted upside down in sealed metal chamber. Compressed N gaz allowed slowly in the chamber. When droplets appear, gaz pressure chamber = pressure potential in twig. W=Wp +Wpi. 36 Begouen-BIOL205-Winter2015 LECTURE 11: UPTAKE AND ASSIMILATION OF NUTRIENTS IN PLANTS. 1) Why do organisms need minerals Nucleic acid/proteins have structure made with salt-bounded mineral elements. This relationship old as life origin. Without presence of appropriate ions in good concentrations, many biological molecules dysfunctional 2) Essential elements 19 essential elements Non mineral elements (H, C, O) Mineral nutrients (16) Can be categorised in macro and micro nutrients - Macro nutrients (N,K,Ca,Mg,P…. ) - Micro nutrients How to find out if some mineral = essential Have 3 criteria. Criteria = - Essential for life cycle - Deficiency symptom when not present - Cannot be replaced by chemical essential elements Difficult to determine nature for some elements because some concentration needed where very low (Ex: Boron). 3) Macro- and Micro- nutrients Elements are not required in same amounts. Based on requires amount, can be macro (large amount needed) or micro (small amount needed) Non-mineral Are required in quantities at least 30 x more Macro-nutrients Required in amounts 10 x more than micro-nutrients 4) Functions of different mineral elements Essential elements can be grouped according to type of function they have in plant. Some of them Are structural part of C compounds Other Maintain structural Integrity Rest Is in ionic form will form transient association with enzymes and other macro molecules to maintain structural integrity. Functional grouping of mineral elements - nutrients part of carbon compounds N and S 37 Begouen-BIOL205-Winter2015 - Nutrients for E storage = structural integrity P, Si, B Remains in ionic form protein binfing + osmoregulation K,Ca,Mg,Cl,Mn,Na Involved in redox reactions Fe, Zn,Cu, Ni, Mo Minerals ions mobile: Cl, K, Mg. Move through plant thanks to signalling mechanism Immobile B,Ca,Cu,Fe,S even if deficiency somewhere won’t move 5) Availability and adequacy of mineral nutrients Many of essential nutrients are not available as elements: exist in soil as dissociated salts: Cations: attached to soil particles (they have an abundance of negative charge) Anions: Are in solutions Both of their availability very influenced by pH of soil For each nutrient Range of optimal concentration Below: Nutrient is deficient Above: Concentration of nutrient = toxic. For macronutrients, range is broad BUT is narrow for micronutrients. When soil = deficient, plantsdeficiency symptoms. Distribution of those symptoms: determined by fact of if mobile or immobile inside the plant. If mobile : transported from older to younger organs. Symptoms won’t appear in younger until older don’t have any. 6) Artificial nutrient solutions To facilitate experimentation: artificial nutrient media for growing plants. Most widely used = Hoagland solution Only for growing whole or intact plants (that can do photosynthesis) If want to cultivate tissues or else, need to add vitamins and sugars 7) Assimilation of highly oxidized mineral nutrients In death all biological elements = oxidised Life = reduction and Death=oxidation Mineral elements taken up highly oxidised like NO3- , SO4 2-, H2PO4- must be reduced in order to be assimilated. SO4 2- undergoes 3 distinct process : - Activation - Reduction - Assimilation or Incorporation 38 Begouen-BIOL205-Winter2015 Activation use of 2 molecule of ATP, produces APS and then PAPS. Positive change in free E , can’t happen spontaneous, happens thanks to breakdown of PP in 2 P Reduction APS and PAPS reduced to sulphite and then sulphide. Assimilation sulphide is incorporated in aa serine or homoserime produce 2 sulfurcontaining aa : Cysteine and methionine. Phosphate assimilation P is added to ADP ATP either during glycolysis in citric acid cycle or by utilizing energy H+ motive in chloro and mithochondria Conversion alpha-keto to succinate accompanied by ATP synthesis in plants and GDP in animals. Nitrate assimilation Nitrate taken up by the root, transported to shoot by transpiration stream. Enters cytoplasm of root and shoot cell by nitrate/H+ symport. In cytoplasm, it is reduced to nitrite by nitrate reductase as shown below: Nitrite = toxic. Will be transported to cytoplasm, ferridoxin (e- carrier) used as e- donor to reduce nitrite to ammonium incorporated into glutamate to synthetize glutamine. Nitrate reductase Inducible enzyme (= activated only when nitrate available) . Activity will appear first in the root. Function in the form of a dimer, but each catalyzing nitrate reduction . Has a NADH + FAD binding site near carboxy terminal. e- flow from NADH to NAD (on C terminus) on the N-terminus. Nitrate Nitrite Nitrite reductase Iron-sulfur complex bound to reducrase, takes e- from reduced derridoxin, passes them to heme, later nitrite converts it to ammonium 8) Plants with special strategies to acquire mineral supplements. Some plants association with mycorrhizal fungi It supplies mineral nutrients tp plant and pant provides carbohydrates to fungi. This relationship establishment requires complex signalling between them. Plant root requires strigolactones to stimulate growth of fungal hyplae towards root. SEE STEPS in book. Insectivorous and parasitic plants : Insectivorous plants : catch insect to get protein supplement. Prot broken down into aa. Plant obtain already reduced and assimilated nitrogen. Parasitic plant, obtain all nutrients from host. 39 Begouen-BIOL205-Winter2015 LECTURE 12: BIOLOGICAL NITROGEN FIXATION AND ASSIMILATION. 1) Importance of N in plant nutrition Most important cell constituents: proteins and nucleic acid = nitrogenous derivative of carbon backbone. DNA/RNA = nitrogenous cell constituents Almost all enzymes= proteins N essential to build, maintain and degrade living systems. Atmosphere = 80 % N2 BUT animals/plants don’t harvest it Most common deficiency = N2 Bound E = 226Kcal very hard to break 2) Abiotic fixation of atmospheric N2 In nature: Some phenomena result in fixation of atmospheric nitrogen: Lightning breaks water & atmospheric N2 nitric acid (HNO3 ) Will wash down to earth as nitrate. Nitrate in the soil available to plant. Will reduce and assimilate it through activities of nitrate reductase (cf lecture 15) Can also be done chemically, is used in industry as the Haber process : Under high P, and with metal catalyst and high T : Add H2 The 2 gases react conversion to ammonia N2+3H22NH3 3) Biological fixation of atmospheric nitrogen. Free living and symbiotic nitrogen fixing prokaryotes : There are bacteria which fix nitrogen ( exclusive capacity) = cyanobacteria + aerobic one :all free-living organisms Some bacteria live in symbiotic association will fix N2 and receive carbon in return. Ex: rhizobium/azorhizobium ( in legumes) . Association can only be formed with the 1 specie highly specific. Nitrogen fixation extremely sensible to O2 Nitrogen fixing enzyme (nitrogenase) only active when very low or 0 O2 N2 fixing organism have evolved diff strategies to maintain anaerobic microclimate around nitrogenase : - Intense respiration (very O2 consuming = minimised O2 inhibition of nitrogenase) 40 Begouen-BIOL205-Winter2015 - In photosynthetic bacteria, photosynthesis occurs in day ( = production O2) and nitrogen fixation during night (= when O2 is not being production by system 2) = Temporal partioning. - In cyanobacteria Special cells to fix N2 (called heterocysts-10 x bigger than other cells) and other are doing photosynthesis = Spatial partioning. - In Leguminous plants that fix N2 roots nodule have a O2 binding protein = Leghemoglobin binds O2 20 x more tightly than our hemoglobin no free O2 in cells. Rice has a symbiotic system with a N2-fixing cyanobacteria: Anabaena Symbiotic N2 fixation in higher plants : All higher plant fixing N2 thanks to symbiosis = Legumes. Have formed symbiose with Rizobium. One specific form of rhizobium associates with a particular specie highly selective. Development of the root nodule : 1) Growing roots secrete flavonoids attracts rhizobia 2) Exchange of sequential signals 3) Rhizobia attach themselves to young emerging root hairs + chem from the root activate bacterial prot 4) Root curls to form small compartiment enclosing rhizobia 5) Activation of other nodulation genes by bacterial prot 6) Infection thread ( produced by bacteria) going from root hair to cortical cells of root mass of cells will form new nodule ( once concentration is sufficient) 7) Mature nodule = spherical and filled with rhizobia Not in cell, is surrounded by plasma membrane (= invagination ) Synthesis of Leghemoglobin Plant synthesixes Globin protein Bacterium synthethize Heme ( contains Fe) Symbiotic action of the two Leghemoglobin Nitrogenase action. Composed of 2 types of complex : Fe ( = iron protein complex) and MoFe (=molybdenium-iron protein complex)/ Ferredoxin is reduced to iron prot complex Releases e- Latter is reduced , will bind and we will have hydrolysis of ATP (change of confo in the process) Since changed confo can reduce MoFe Latter will reduce N2 to NH3 In the last step e- and H+ = lost to H2 will reduce efficiency by up to 60 % Some plant hydrogenase to be more efficient ( splits H2 and retakes e- and H+) Overall reaction : N2 +8e+8H+16ATP 2NH3+H2+16ADP+16Pi 41 Begouen-BIOL205-Winter2015 Nitrogenase other enzymatic activities : - Azide reduction - Acetylene reduction - H2 prod Export of N2 from the nodule. Once N2 is fixed as NH3 in nodule needs to be exported to the rest of the plant BUT NH3 = toxic has to be converted to other compounds that will be exported through xylem in solution form. Amide exporters Temperate regions legume (pea,clover etc) export fixed nitrogen as amides. Principle amide exporters = asparagines and glutamine (serve as nitrogen stores) 1st : NH3 +glutamate (aa) glutamine ( by glutamine synthase) 2nd ; amino group from glutamine + aspartarte (another aa) asparagines (by transaminase enzyme) 2glumatate + 2ATP + 2NH4 2glutamine( 1exported) 1Glutamine +1 ketoglutarate +NADH + H+ 2 Glutamate Glutamine+ Aspartic acid Glutamic acid + asparagines Other legumes don’t synthetize amides BUT Ureide. Ureide = exported by legumes of tropical orgin (ex:soybean, peanut) 3 major ureides = allantoic acid, allantoin and citrulline. Long serie of reaction before N2 is incorporated. Allantoin synthetised in peroxisome from uric acid. Allantoic acid from allantoin in endoplasmic reticulum (ER) Citrulline from aa ornithine, site is unknown. All of them are released in xylem by respiration stream. Once at destination, are metabolized to release NH4+ or NH3 ( will then be incorporated in amide as seen previously) 4) Agricultural importance of biological N2 fixation. 180 million metric tons of N2 biologically fixed each year. Usually, leguminous and non-leguminous crop alternate. When leguminous crop = planted in field after leguminous crop, yield = higher 42 Begouen-BIOL205-Winter2015 5) Terrestrial nitrogen cycle 3 N pools 1. Atmosphere 2. Soil : After nitrification 3. Biomass ( when we die ammonification of our bodies ammonium release and goes back into soil. ) Some bacteria convert nitrate to N2 and some ammonia nitrate =nitrification and some nitrate to N2 =denitrifying bacterias 43 Begouen-BIOL205-Winter2015 LECTURE 13 : TRANSPIRATION AND DISTRIBUTION OF MATERIALS IN PLANTS. 1) Xylem = water-conducting tissue. We know that water movement through xylem tissue (will also carry sucrose, transposable form of photosynthesis). Showed by Bark experiment: Removed ring (=phloem) and plant showed no sign of water deficiency + sucrose pack at the top. When opposite experiment made, plant interrupted water supply to upper plant of the plant. upward water movement in plants occurs through xylem vessels. 2) Structural elements of xylem involved in upward water movement Each xylem vessel made of xylem elements, each derived from a cell and put end-toend. Xylem vessel = continuous tube formed from xylem elements. Xylem elements dead and hollow, have perforation plates at the end and at the sides. In angiosperms, vessel from tube from root to shoot. Another cell type taking place in upward water movement tracheids = elongated, spindle-shaped cells (also hollow and dead) do not form long tubes but overlap with each other along part of their length. Gymnosperms Only have tracheids Angiosperms tracheids and vessels. Because vessel and tracheids have perforations (called bordered pits) water can move from one vessel to the other OR from one tracheid to another. In vessel, secondary cell wall = laid down over primary cell wall in various patterns. (there is also bordered pits on side walls) Water can flow across these pits if they are aligned. One advantage of having large number of adjacent vessel/tracheids provide many branched paths for water movements = Particularly helpful if there is discontinuity to water flow within a vessel because of cavitation. 3) Diurnal fluctuations in transpiration. Transpiration shows diurnal fluctuations stomata open during day and close during night (except in CAM plants, where opposite = true). Once water is withheld after watering, soil water potential starts declining with time 44 Begouen-BIOL205-Winter2015 When water potential of root & leaf shoes diurnal fluctuations along with overall decline with time. 4) Forces driving upward water movement. We have seen various contributing forces: root pressure and capillary rise. We can consider pulsation in the endodermal forces. Root pressure. Many manifestation well-watered seedlings of grasses show drop of water at their tips during mornings = guttation result of water absorption by root during night (when little transpiration occurs) During night root water potential = lower than the one of soil during night, waters enter the roots. Because no transpiration at night positive hydrostatic pressure push sap out will rise in manometeric tube This pressure can push water up to a maximum of about a meter cannot account for water rise in tall trees. Capillary rise of water. Liquids rise in capillary tubes as function of their surface tension and density and as function of the radius of capillary tubes. As max capillary rise occurs and becomes stationary forces pulling liquid up = forces pulling it down. Since these forces are equals we can calculate height to which given liquid will rise. For water: height at which it will rise = 1,49*10^-15/(radius of capillary in meters) Cannot account for rise of water in tall trees. SEE book for equations. Cohesion-Tension theory. Water molecule bind to each other with large cohesive forces can support very long vertical columns. When column top = lifted up by suction, whole column rises. When transpiration occurs at top of plant, creates suction force that lifts whole column of water in each xylem vessel up. (Won’t break because of the cohesion forces) Continuity of water columns in xylem established early during seeding development. Water columns might break during strong winds when plant violently shaken(= appearance of air bubbles). In tall trees = irreparable. 45 Begouen-BIOL205-Winter2015 Plants have evolved excellent adaptation against occasional breaking of water column continuously form new xylem through secondary growth (while old one = non-functional) = darker area in trees. 5) Gradient of decreasing water potential from bottom to top of a tree. Water goes from high potential to a low one. As we go from soil to root to xylem to top successive decrease in water potential. BUT lower water potential = in the air outside. When extreme suction, water potential can become less than 0. Due to high P created by intense transpiration, diameter of tree decreases just after noon and recovers in the evening. Once water finally reaches leaf xylem, it goes from cell to cell by osmosis finally gets released into substomatal cavity (Large space inside stoma) Movement of water from substomatal cavity through stoma out to the atmosphere takes place in vapour or gaseous form. 6) Water movement from substomatal cavity to the atmosphere. This movement = by diffusion, is driven by diff in water vapour concentration between substomatal cavity and the air surrounding the leaf. Transpiration stroma commonly expressed as flux density ( J) or less common as total flux rate of water loss (Q) in terms of total water loss per unit time See book for equations The longer the path, the greater the resistance ( R is measured in time) In transpi throught stomata, resistance R 2 components : - Stomatal Resistance (Rs) - Air resistance (Ra) Water movement from substomatal cavity to atmosphere via stomatal opening. Stomata resistance (Rs) Resistance to water mov = directly proportional to length (l) of stomatal pore and inversely proportional to cross sectional area of pore + resistance due to presence of water vapour in stomatal pore =1/2r Rs= l/pi*r^2 + 1/2r Pi*r^2 = cross sectional resistance Resistance due to unstirred air boundary layer (Ra) 46 Begouen-BIOL205-Winter2015 due to unstirred air presence , water vapour escaping 1 stoma mixes with vapour coming out of another one forms layer of water-saturated air How thick depends on length of leaf in wind and velocity of wind. Shorter leaf dimension in direction of wind = smaller thickness of unstirred boundary layer and lower Ra Smaller Ra = higher rate of transpiration Ra = lower in plants with shorter leaf width Transpi rate increases with decrease in leaf width. Size of opening of stomatal pore also determines the rate of transpiration. Increase in the size of the opening will have effect on rate of water loss or on moving air gets bigger. When air = still, transpiration increase with increase in opening up to 5microm but not after Rate of water loss = limited by thickness of unstirred boundary layer. When air moving = linear increase in rate of water loss with increase in the opening of the pore. Water loss = limited by size of pore opening. 7) Significance of transpiration 1. High water content confers turgidity that is essential for optimal cell function and provides physical driving force for cell expansion and thereby growth 2. Transpirational cooling of leaves in hot environments 3. Serves as a vehicle for nutrient transport 47 Begouen-BIOL205-Winter2015 LECTURE 14 : DISTRIBUTION AND PHOTOSYNTHETIC PRODUCTS IN PLANTS. 1) Identification of the phloem as the transport tissue Bark cut experiment Removed ring bark after time, bark above girdle swelled up, sugar accumulation. All parts below died. evidence that photosynthetic products are transported through phloem (= inner part of the bark) Phloem = in vascular bundles. Phloem = towards outside (epidermis) and Xyleme= toward inside (center of the stem) During secondary growth circular arrangement of vascular bundles = changed (most central part of stem has to be occupied by xylem- need to increase diameter faster than height. More recent experiment with C14 datation confirmed that phloem was the transport pathway for organic materials. Cells made in dry season = smaller than those in wet season 2) Structural features of the phloem Complex tissue containing several cells types. 2 major cell types = Sieve elements: Elongated cell , with end wall perforated with pores. Open for transports, will form tube ,by arranging themselves end to end. Tube will run through entire plant length. Look a little bit like Xylem but is not empty, needs system to transport water. Need little ATP Filled with sieve plates, on side: Lateral sieve area -Companion cells: Also elongated cells. Allow sucrose to pass to sieve elements Narrow long cells next to sieve elements, will have cytoplasmic connections with them through branched plasmodesmata.. Have a nucleus and a lot of mitochondria, do a lot of ATP. Lot of plasmodesmata (=gap junction ) = opening between 2 cells. Some have a convoluted plasma membrane increase membrane surface area increase transport. Sieve element + Companion cells functional complex 3) Source and sinks organs Keaf = source organs for photosynthate If we do photosynthesis with radioactive carbon , C incorporated into sugar, only cells where sugar went will show radioactivity Phloem sap: Took insect, stucked it in phloem ??? 48 Begouen-BIOL205-Winter2015 Found out major part = sugar and sucrose Rate Velocity = 0.5-2.5/min Flux density=15g/h/cm^2 Excess in far the rates that could be obtained by diffusion Is driven by pressure potential Which source supplies which sink ? Found out that bigger leaves supply only small leaves on the same side Sucrose loading Companion cells then apoplast of sieve elements Protons pumped into apoplast H+ and sucrose cotransported by sucrose-proton symporter into cytoplasm of sieve elements But what force drives it Pressure flow hypothesis Created experiment with 2 flasks , both completely filled ( no air) One flask = sink = Xylem Other = source with sucrose = Phloem Water potential lower in sucrose solution, water will enter through osmosis, so solution is pushed out goes into sink. As sucrose comes in, water will leave the bag by osmosis but sucrose won’t. It all starts again Requirements : Sieve plate pores unobstructed È??? Photosynthates Unidirectional movement Chillimg = T where ATP production almost completely stops LECTURE 15: Water an ion balance in animals. Water gain = Drinking/ Uptake through body surface (water or air) /Water in food/Oxidation or metabolic water (when starch/glycogen are being degraded) Water loss = Evaporation from body surface …. Metabolic water : For each gr produced , gr of waters Starch=0.56 , Fat=1.07, protein =0.39 (urea in urine = Ureptelic) …. House mite Loss a lot of their weight when no water ( absorb thorug humidity) Namib Desert Beetles : Will absorb water from fog/most air and does head stand Water will go down his body to his mouth 49 Begouen-BIOL205-Winter2015 Importance of maintaining favourable water and ion balance Optimal cell function Optimal hydration degree Optimal solutes C Water balance and solute/ion balance = intimately related Loss of water increases concentration of various ions, Absorption of solutes/ions = water influx Animals osmoconformers or osmoregulator ( Don’t care about outside ions concentration = regulator) Animals Looses lot of water through evaporation Loss of water through body surface decreases with body size increase Remember : V increase ^3 & Surface ^2 Many insects exoskeletons ( outside body ) Cuticular melting point : When cuticule melts, water loss is crazayyy Mammals Can’t tolerate water loss very much … In burrowing animals (ex: desert) t cooler in burrow then outside slower water loss + secrete very concentrated urine + Drier feces In high animals, body -|> compartiments Marine and Fresh water animals Intra-cellular Extra cell or interstial External bathing Excretion of Nitrogen waste products : Ammonia, Uric acid and Urea toxic Animals have diff strategy to get rid of them. Ammonioteles (Simple invertebrates, aquatic mollusc Ammonium Uricoteles (Terrestrial mollusc, terrestrial arthropods, Reptiles, Birds) Uric acid Ureoteles (Mammals, some larval body fish) Urea Evolution of kidney Flat worms : Have a canal where there are Flame cells fluid form outside body will enter through there and be filtered after can associate with solute. Annelids or segmented worm Have segments that will be repeated multiple times In each have a pair of metanephridium = Fluif enters Metanephridium through nephrostome. Excretion = from nephridiopore For primitive invertebrate enters through mephrostome , long tube with very little water loss 50 Begouen-BIOL205-Winter2015 Insects different Malpighian tubules. Just before rectum = branching in tubules. In tubules cells that filter body fluid. Will allow passage of only the necessary water to go further, rest is absorbed back. Kidney : Single filtration unit = nephrons Glomerulus filtrates blood, takes back water and mineral In the loop of Henle= contercurrent system Glomerulus : Artery bringing blood to glomerus cn contracte , will increase pressure ( by difference with the other artery radius 51 Begouen-BIOL205-Winter2015 LECTURE 16 : Exchange mechanism in Animals Breathing media contain O2 Air as breathing medium : 21% air= O2 1L=209ml O2 = 280 mg O2 Water as breathing medium: 1L water = 7ml/10mg O2 Much more water needed to extract needed O2 Water = 800 times more dense than air = 55 times more viscous. Diffusion coeff of O2 Much more higher in air than in water. Molecules in air can travel much more distance before colliding with each other Tracheal Gas exchange system in insect In all insects: Have hole in body: Spiracles Inside spiracles, atmospheric air goes everywhere in body. 2 others structures used for breathing : Gills Formed by evagination. Can be divided into lobes. In tuft gills , O2 doesn’t go into lobes, lobes just increase respiratory surface Filament gills, water goes into every single lobe Lamellar gills : Water and blood go in , made of plate one behind each other. Each plate has its own circulation Ex: Fish gills : water flows uni-directionally over exchange surface . Each arch = isolated Have their own filament stacking. Made up of thin walls filled with blood capillaries . Blood will pass from one vein to the other through arch through capillaries Counter-current flow of water and blood Lungs Many designs in nature. Lot of “experiment” Amphibia Have proper lungs Formed by invagination. Inner lining made into lobes made into lobes increases surface area Mammalina lungs = super efficient. Each lungs collection of air sac ( alveoles) stacked together Birds = master of breathing. Have 2 cycle of breathing (1,21,2…) Have lungs AND air sacs Also bones Have air cavities get air in bone marrow + reduce total skeleton weight 2 breathing cycle = Most efficient system Us Goes both way In birds , respiration = unidirection system, 52 Begouen-BIOL205-Winter2015 There is one air sac before lung (anterior sacs) and another one behind (posterior sac) 1st breath O2 inhaled directly into posterior sac exhalation Goes into lungs through other path 2nd breath Goes into anterior sac 1cm^3 lung = 600cm^2 surface area ( =1mL !!) Atmospheric air Fills interior Diffusion distance (DeltaX) in air –breathing animals Diffusion = very efficient on short distance = more efficient on mammals If we reduce membrane thickness, deltaX = steeper Increase diffusion rate Other way = to increase diff between 2 concentration gradiant !! pay attention to unit !! Respiration in an egg Average egg 10000 pores gaz exchange + water loss During 21 days incubation : O2 taken in = 6L=8,6gr CO2=4,5L=8.8 gr loss Water vapour =11L = 8.8gr loss If we take it to 4000 m Less O2 availible BUT diffusion quicker because fewer molecules to collide with (Diffusion ceff = *2) Total number pore decreases = Less water loss Concurrent Flow VS Countercurrent flow of wate & blood Concurrent : Saturation happens very quickly ,equilibrium is reached , no more reactions Countercurrent : Whatever quantity we choose, always higher O2 concentration in water than in blood. Can never reach equilibrium. Ventilation and Perfusion flow : Ventilation rate : Rate of flow of O2 rich medium over respiratory surface Perfusion rate: Rate of blood flow over respiratory surface Both occur through diffusion How the fish breath ? Mouth takes water, goes trough mouth , gets out at the gills. At the gills : arch allow water in , thanks o increase V Decrease Volume --. Closes mouth, open operculum , water leaves through there , O2 was taken by gills . CO2 more soluble in water than air More removal by fishes 53 Begouen-BIOL205-Winter2015 Water being denser than air provide structural structure to gill maintenance, Aquatic life style no need of strong skeleton 54 Begouen-BIOL205-Winter2015 FOR EXAM Photosynthesis!!! + red drop always here Calvin cycle do not need to memorize it , just RUBISCO RuBP now them C3 C4 CAM need to know different Lecture 2p.30 +active (use ATP)/ passive transport Allometric Plasmodesmata MEcanism of Osmosis Lecture 3 p.5 Diagram on p14 How would you calculate light E in KJ For Animals : MSMR !! Always here Nitrogen fixation Incorporation into amino acid of Serine and Homoserine !!! (Assimilation ) If not isometric Allometric Location or carbo/decarboxylatin Why kerb only operate under aerobic conditions. O2 needed to be e acceptor. Without it -> NADH and FADH2 would accumulate Lecture 8p6 MSMR AT THE TEST : Question on freezing water RU 55