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Topic 2: Homeostasis in Organisms What is Homeostasis? Maintain a stable internal environment such as body temperature or pH Biochemical processes- chemical reactions that occur in living organisms Plant Nutrition: Photosynthesis How do organisms obtain their nutrition? Heterotrophs- can’t make own food- obtain from other organisms Autotrophs- make food from inorganic compounds Photoautotroph- use light energy Chemoautotroph- use chemical energy Who does what kind of nutrition? Heterotrophs- animals, fungi, some bacteria Autotrpohs- plants, many protists and some bacteria Plants are autotrophs Photosynthesis: use light energy to convert small inorganic compounds into food (glucose- simple sugar) How do plants get energy from light? Sunlight contains radiation energy How do we know sun contains energy? Ex: a day at the beach… Equation for Photosynthesis Goal of photosynthesis: make GLUCOSE Starting products of photosynthesis: Sunlight Carbon dioxide CO2 Water H2O End products Glucose C6H12O6 Oxygen (O2) Water H2O Where does photosynthesis take place? Chloroplasts- contain the photosynthetic pigments Equation for Photosynthesis The balanced equation for photosynthesis is: 6CO2 + 12H2O + light C6H12O6 + 6O2 + 6 H2O How do plants gather the sun’s energy? Plants can absorb this energy using pigments Other wavelengths of light not absorbed are reflected The color we see is reflected light Plant Pigments- Why are plants green? Chlorophyll- absorb red and blue light and reflect green light Chlorphyll “a” is main photosynthetic pigment Carotenes- orange Xanthophylls- yellow Why do plants have these accessory pigments? ANSWER: Allow plant to absorb more light Fate of Glucose Glucose can be used as a food resource Glucose can make (synthesis) complex molculeules ATP, DNA, Carbohydrates, Lipids, proteins Cellular Respiration Obtaining energy from food! What is respiration? Respiration- convert the energy in glucose into usable energy for the cell by breaking the bonds between atoms What is formed from respiration? Make energy molecules ATP! Enzymes are needed in order for the chemical reactions to take palce Types of Respiration Aerobic- respiration requiring oxygen Get the maximum amount of energy from glucose Takes place in MITOCHONDRIA Anaerobic- respiration without oxygen Get only a small amount of energy out of glucose Many forms of bacteria Yeast cells Summary of Aerobic Respiration C6H12O6 + 6O2 6CO2 + 6H2O + Energy (36 ATP) Glucose + oxygen carbon dioxide, water, and ATP Carbon Monoxide Poisoning Toxicity primarily results from cellular hypoxia caused by impedance of oxygen delivery. CO reversibly binds hemoglobin, resulting in relative anemia. Because it binds hemoglobin 230-270 times more avidly than oxygen, even small concentrations can result in significant levels of carboxyhemoglobin (HbCO). Interferes with electron transport chain Enzymes Enzymes Enzymes- proteins that speed up chemical reaction Usually end in –ase and rest of name comes from substrate acts on Involved in digestion, respiration, reproduction, movement etc. Enzymes Enzymes are catalysts- brings about reaction without being changed (get reused) Substrate- what the enzyme is changing Parts of an enzyme Active site- part of the enzyme at which the substrate attaches Enzyme-substrate complexwhen enzyme and substrate join together Enzyme activity is regulated- WHY? Inhibition- slow down how fast enzyme works or shut down Lock and Key Model Active site Enzymesubstrate complex Induced-Fit Model Factors that Affect Enzyme Action Temperature- work best at certain temperatures High temp, molecules move fasterenzymes work faster Too hot- proteins fall apart- denature pH- varies depending on the enzyme (amino acids made of) Factors that Affect Enzyme Action Concentration of enzyme Little enzyme, lots of substrate- enzyme limits reaction rate Add more enzyme, increase until all substrates are in active sites Factors that Affect Enzyme Action Concentration of substrate Little substrate, lots of enzyme- substrate limits reaction Add substrate- increase until all enzymes being used Temperature Effects of pH In stomach In intestine Enzyme concentration constant Substrate concentration constant Enzyme Worksheet Enzyme Worksheet page 2 Enzyme Worksheet Y Axis = dependent variable = _________ X- Axis = INDEPENDENT VARIABLE = _____________ Amylase Enzyme Activity at Different Temperatures 1.1 1 Rate of starch conversion (grams/minute) 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 5 10 15 20 25 30 35 40 45 50 Temperature Celsius Rate of starch conversion (grams/minute) 55 60 65 70 75 Feedback and Homeostasis Which graph of blood sugar level over a 12-hour period best illustrates the concept of dynamic equilibrium in the body? (1) (2) (3)(4) Feedback Mechanisms Positive Feedback- early part of childbirth Negative Feedback- like a thermostat Negative Feedback Viruses and Disease Pathogens- viruses/bacteria and other organisms that cause disease Antigens- molecules that trigger immune response Viruses damage or destroy cells AIDS- attacks immune system – helper T cells Weakened immune system cause of death Linked to cancerous tumors Can carry oncogenes- genes that cause cancer Viruses and immune defense Immune system has three main functions: Recognition Destruction Memory Immune Defense Initial protection comes from FIRST LINE DEFENSES SKIN Mucous- trap pathogens, wash them away Cilia/Hair Enzyme/Acids Sweat, Tears, Saliva Immune Defense If get past first-line, second line defense: Inflammatory response- swelling, redness, warmth in area of infection Cells release chemical - get increased blood flow Attract macrophages- giant white blood cells- swallow up bacteria Interferon- causes cells to produce enzyme that stop viral reproduction Immune Response Third line defense- IMMUNE SYSTEM Helper T cell Killer T cell B cell Suppressor T cell Memory T cell- help if get infected again Immune Defense Summary white blood cells engulf pathogens B cells make antibodies Antibodies attach to antigen Leads to destruction of antigen Allergies Immune response to environmental substances such as pollen dust, insects, etc Antihistamines used to combat