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Ch 9 Cellular Respiration What is Cellular Respiration? The Big Picture • Catabolic Pathways and Production of _____ ATP FERMENTATION – _________________catabolic process that is a partial degradation of sugars that occurs without the use of OXYGEN ____________. CELLULAR RESPIRATION catabolic pathway that is the most – _____________________OXYGEN efficient and prevalent. ______________ is consumed as a reaction with organic fuel. In eukaryotic cells, MITOCHONDRION is the location. _________________ – Formula of Cell Respiration C6H12O6 + 6 O2 6 CO2 + 6 H2O + ENERGY – Redox Reactions: • Why do catabolic pathways that decompose glucose and other organic fuels yield energy? – The relocation of electrons released energy stored in organic molecules and is used to synthesize ATP. • Na + Cl Na+ + Cl- • A redox reaction that relocates electrons (very electronegative) RELEASES closer to oxygen _____________ chemical energy that can be put to work. • Example with Cellular Respiration Formula Pg 162 – Energy Harvest via NAD+ and the Electron Transport chain GLUCOSE • Cellular respiration breaks down ____________ and other fuels in a series of steps that strip electrons from glucose (creating sources of energy). • For each electron, a hydrogen atom (proton) is present. The hydrogen atoms are not transferred directly to oxygen but pass + NAD(nicotinamide to an enzyme called ________ adenine dinucleotide) DEHYDROGENASE • The enzyme __________________ removes a pair of hydrogen atoms (2 e- 2 protons) from the substrate. The enzyme delivers the two electrons along with one proton to its coenzyme, NAD+. The proton is released as an H+ into the surrounding solution. • Formula Pg 162 • NAD+ is ______________ REDUCED to NADH. Each NADH molecule formed during respiration represents stored energy that can be tapped to make ATP when the electrons complete their FALL “________” down an energy gradient from NADH to oxygen ELECTRON TRANSPORT CHAIN to • Respiration uses an ____________________________ break the fall of electrons to oxygen into several energyreleasing steps. • Summary: FoodNADH ETC Oxygen GLYCOLYSIS • ______________ (the first metabolic stage of respiration) – Glycolysis harvests chemical energy by oxidizing GLUCOSE ___________ to pyruvate. – Two Phases INVESTMENT phase: cell spends ATP • Energy ______________ – Formula: 2 ATP 2 ADP + 2 P PAYOFF • Energy ______________ Phase: ATP is produced by substratelevel ___________________ PHOSPHORYLATION and NAD+ reduction to NADH by electrons released from oxidation of glucose. – Formula: 2 NAD+ + 4 e- + 4 H+ 2 NADH + 2 H+ 2 ATP and __ 2 • Net energy yield from glycolysis per glucose is ___ NADH • Glycolysis releases less than a quarter of the chemical energy stored in glucose while the rest remains in the two molecules of pyruvate. • Diagram: Pg 166-167 fig 9.9 • Basic overview awesome glycolysis • step by step Glycolysis • The Citric Acid/ Krebs Cycle- occurs when oxygen is ______________ PRESENT PYRUVATE – ______________ enters the mitochondrion via active transport where the enzymes of the citric acid cycle complete the OXIDATION ______________. – Steps of Citric Acid Cycle (p.169 Figure 9.12) • 1. Pyruvate is converted to a compound called acetyl ACETYL CoA coenzyme A or _________________. – During this step, pyruvate’s carboxyl group which is already CO2 because fully oxidized is removed and given off as ______ it has little energy. – The remaining two-carbon fragment is oxidized forming acetate. An enzyme transfers the extracted electrons to NAD+, storing energy as NADH _________. – Coenzyme A is attached to acetate by an unstable bond making the acetyl group very reactive. This results in ACETYL CoA ______________ and is ready for its acetyl group to be oxidized. • 2. Acetyl CoA adds its two-carbon acetyl group to oxaloacetate producing citrate DECOMPOSE – The next seven steps ______________ the citrate back to oxaloacetate. • 3. Citrate is converted to its isomer isocitrate by the ______________ of one water molecule and the addition of REMOVAL another. • 4. Citrate loses a CO2 molecule and its result is OXIDIZED ______________, reducing NAD+ to NADH • 5. Another CO2 is lost, and the result is oxidized, reducing NAD+ to NADH. The remaining molecule is attached to coenzyme A UNSTABLE by an ______________ bond. PHOSPHATE • 6. CoA is displaced by a ______________ group, which is transferred to GDP, forming GTP, and then to ADP, forming ATP SUBSTRATE phosphorylation) (__________-level HYDROGENS • 7. Two ______________ are transferred to FAD, forming FADH2 and oxidizing succinate. WATER • 8. Addition of a ______________ molecule rearranges bonds in the substrate. • 9. The substrate is oxidized, reducing NAD+ to NADH and REGENERATING oxaloacetate. ______________ – Krebs animation 1 – Krebs Cycle • Electron Transport Chain – The ETC is a collection of molecules embedded in the INNER MEMBRANE ____________________ of the mitochondrion. The folding of the inner membrane of the mitochondrion. – Since the cristae contains many folds, it provides space for THOUSANDS ______________ of copies of the chain in each mitochondrion. – Sequence of electron carriers (p. 171 Figure 9.13) REDUCED – Electron carriers alternate between ______________ and oxidized states as they accept and donate electrons. – Each component of the chain becomes reduced when it accepts electrons from its “uphill” neighbor which is less ELECTRONEGATIVE ________________and returns to its oxidized form as it DOWNHILL passes electrons to its “______________,” more electronegative neighbor. – Steps of the ETC FLAVOPROTEIN because it has a • The first molecule is a ______________ prosthetic group called flavin mononucleotide (FMN) • The flavoprotein returns to its oxidized form as it passes ELECTRONS ______________ to an iron-sulfur protein (Fe*S). • The iron-sulfur protein then passes electrons to a compound called ubiquinone. Ubiquinone is MOBILE ________within the membrane rather than residing in a complex. • Most of the remaining electron carriers between ubiquinone and oxygen are proteins called CYTOCHROMES ______________. HEME group which has an iron • Cytochromes have a prosthetic ______ atom that accepts and donates electrons. DIFFERENT – Each of the cytochromes in the ETC has a ______________ electron-carrying heme group. – FADH2, another reduced product of the citric acid cycle is another source of electrons for the ETC. FADH2 adds its electrons to the ETC at complex II at a ______________ LOWER energy level than NADH does. – Function of the ETC DIRECTLY • The ETC makes no ATP ______________. EASE the fall of electrons from food to • The function is to _____ oxygen to break a large free energy drop into a series of MANAGEABLE amounts. smaller steps that release energy in ______________ – _________________- The Energy Coupling Mechanism CHEMIOSMOSIS • ATP synthase is an ______________ located in the inner ENZYME membrane of the mitochondrion. – ATP synthase makes ATP from ADP and inorganic ______________ PHOSPHATE – ATP synthase works like an ion pump in ______________. REVERSE – Uses energy of an existing ion ______________ to power ATP synthesis by phosphorylation. GRADIENT – The power source is the proton gradient and therefore is the difference in ______________ of H+ on opposite sides CONCENTRATION of the membrane. • Chemiosmosis: The process where energy is stored in the form of an H+ gradient ______________ a membrane being used to ACROSS drive cellular work. (Do not confuse with osmosis) • P 171 Figure 9.14 4 Parts to ATP synthase • How does inner mitochondrial membrane generate and keep the H+ gradient? CREATE the H+ – Electron transport chain purpose is to _______ gradient. – The ETC pumps electrons across the membrane (from the MATRIX to the intermembrane space). mitochondrial ________ BACK across the membrane – H+ has a tendency to move _______ so ions pass through a channel in ATP synthase to drive the phosphorylation of ADP. – The energy stored in an H+ gradient across a membrane couples the redox reactions of the ETC to ATP synthesis: an example of chemiosmosis. PROTON » This H+ gradient is referred to as ________-motive force: capacity to do work • Other examples of chemiosmosis CHLOROPLASTS use to generate ATP during – ______________ photosynthesis (light drives ETC) PROKARYOTES generate H+ gradients across their plasma – ______________ membrane, then tap the proton-motive force to make ATP and pump nutrients and waste across the membrane, and to rotate their flagella. • • • • Electron Transport ETC and ATP Synthesis CR Overview (long) ETC • Total ATP Production by Cellular Respiration – Energy flow: glucose NADH ETCproton motive force ATP – Three main parts of cell respiration • Glycolysis (substrate-level phosphorylation): __ 2 ATP, __ 2 pyruvate, __ 2 NADH • Citric Acid Cycle (_________ Cycle) substrate level phos.: KREBS 2 ATP, __6 NADH, __ 2 FADH2 __ • Electron Transport chain (oxidative phosphorylation): __ 32 or __ 34 ATP • Totals: __ 36 or __ 38ATP • Fermentation – Fermentation consists of glycolysis and reactions that REGENERATE ______________ NAD+ by transferring electrons from NADH to pyruvate or derivative of pyruvate. – The NAD+ can be reused to oxidize sugar by glycolysis resulting in two (net) ATP. – Two types of Fermentation ALCOHOLIC • ______________ Fermentation Steps: – Pyruvate is converted to ethanol (ethyl alcohol) in two steps. The first step releases CO2 from the pyruvate which is converted to the two-carbon compound acetaldehyde. – In the second step, acetaldehyde is reduced by NADH to ethanol. This regenerates the supply of NAD+ needed to continue glycolysis. • Examples: :bacteria: yeast, humans use it to brew beer, make wine, and bread. – • • ______________ acid fermentation Steps: LACTIC ACID – Pyruvate is reduced directly to NADH to form lactate as an end product with no release of CO2. (Lactate is the ionized form of lactic acid) • Examples of Lactic acid fermentation: – Microbial fermentation produce acetone and methanol HUMAN MUSCLE CELLS – ____________________________ make ATP by lactic acid fermentation when oxygen is scarce. » Strenuous exercise when sugar catabolism for ATP production outpaces the muscles supply of oxygen from the blood. » This build up of lactate causes muscle fatigue and pain. fermentation 1 Evolutionary Significance of Glycolysis PROKARYOTES and ______________ EUKARYOTES use – Both ______________ GLYCOLYSIS ATP ______________ to generate _____. Chapter 10- Photosynthesis • Sunlight: the main source of ____________ on Earth ENERGY PHOTOSYNTHESIS process by which light energy from the – ________________: CHLOROPLASTS sun is captured by ________________and is converted to SUGAR and other organic chemical energy stored in _________ molecules. AUTOTROPHS – ________________are “producers”: produce their food from CO2 and other inorganic raw materials obtained from the environment. • The main source of organic compounds for all NONAUTOTROPHIC ________________ organisms. • Almost all plants are autotrophs, specifically PHOTOAUTOTROPHS ___________________since they use light as a source of energy to synthesize organic compounds. • Examples: p.182 Figure 10.2 HETEROTROPHS – ________________are “consumers”: obtain their organic material by consuming compounds produced by other organisms. • Almost all heterotrophs are dependent on __________________ for food and oxygen PHOTOAUTOTROPHS • Introduction to Photosynthesis – • Formula (LEARN): 6 CO2 + 6 H2O + LIGHT C6H12O6 + 6 O2 Plant structure: p. 183 Figure 10.3 – – – – – ________________gives CHLOROPHYLL a plant or leaf its green color as it is a green ________________located within chloroplasts. It is the PIGMENT ABSORBED light energy ________________by chlorophyll that drives the synthesis of organic molecules MESOPHYLL Chloroplasts are found in the cells of the ________________, the tissue in the interior of a leaf Carbon dioxide enters the leaf and oxygen exits by the STOMATA ________________which are tiny pores. An envelope of two membranes encloses the STROMA ________________, the dense fluid within the chloroplast. The THYLAKOIDS ___________ are a system of interconnected membranous sacs that segregate the stroma from the thylakoid space. GRANA • Thylakoids can be stacked in columns called _____________. MEMBRANE • Chlorophyll is located in the thylakoid ________________. – The oxygen released from photosynthesis is due to the splitting H2O and not _____. CO2 of ____ H • The _______ is incorporated into sugar and ____ O is released as waste. REDOX – Photosynthesis is a _________ process • Water is split, and electrons are transferred along with H+ WATER ions from the __________ to CO2, reducing it to a sugar. INCREASE in potential energy as they • Since electrons __________ move from water to sugar, this requires energy which is LIGHT provided by ___________. – Photosynthesis is broken up into ____ 2 phases: DEPENDENT • The light-________________reactions (photo): CHEMICAL energy (____ ATP – Solar energy is converted to __________ NADPH and ______) – Light absorbed by chlorophyll drives a transfer of electrons and Hydrogen from water to an acceptor called NADP+ ____________. SPLIT and releases oxygen. – Water is ______ – Solar power is used to reduce NADP+ to NADPH by adding a pair of ________________along ELECTRONS with a hydrogen nucleus or H+ – ATP is generated by chemiosmosis by PHOTOPHOSPHORYLATION ________________________. – Two products: NADPH and ATP • Calvin cycle (synthesis): Light independent reactions (sort of) CO2 – _______ from the air is incorporated into organic molecules already present in chloroplast. This process is FIXATION called carbon ________________. CARBOHYDRATE – Next, the fixed carbon is reduced to ________________ by the addition of electrons. Reducing power is provided by ________________. NADPH – To convert CO2 to carbohydrate, the Calvin cycle also CHEMICAL requires ________________ energy in the form of ATP. – Dark reactions because it does not require light directly but needs the products of the light reactions. – Products: Sugar (glyceraldehyde-3-phosphate then GLUCOSE ________________) • Sunlight and the light Spectrum – Light is a form of energy known as electromagnetic energy and travels in rhythmic _________. WAVES DISTANCE • Wavelength: the ________________ between crests of waves • Electromagnetic spectrum: the entire spectrum of RADIATION < ________________ ranging in wavelength from _______ a nanometer (gamma rays) to _______ a kilometer (radio > waves). – VISIBLE ____________ Light: From 380 nm to 750 nm. » ___________: discrete particles that act like objects PHOTONS with a fixed quantity of energy. INVERSELY » Energy of photons is ________________ related to the wavelength of the light; shorter wavelength, the ________________ the energy. GREATER » The sun radiates the full spectrum but the atmosphere ALLOWS only ________________ visible light to pass through. PHOTOSYNTHESIS » Visible light drives ________________. – ______________PIGMENT substance that absorbs visible light. • Different pigments absorb (and reflect) light of different WAVELENGTHS ________________and cause the absorbed wavelengths to disappear. • The color we see is the color that is the most ______________ by the pigment. REFLECTED – Example: seeing green or black, or white. SPECTROPHOTOMETER instrument that can measure the • ____________________ability of a pigment to absorb various wavelengths of light. – It directs beams of light of different wavelengths through a solution of pigment to measure the ________________ FRACTION of light transmitted at each wavelength. ABSORPTION – ________________Spectrumgraph plotting a pigment’s absorption v. wavelength. » Pg 187 Figure 10.9 • – Significance: By analyzing absorption spectra of chloroplast pigments, scientists can compare the relative ________________ of different wavelengths for driving EFFECTIVENESS photosynthesis. (How do we know which wavelength is most effective?) ACTION – ________________ spectrum- graph plotting the rate of O2 release or ____ CO2 consumption) v. photosynthesis (____ wavelength ________________the main photosynthetic pigment CHLOROPHYLL – Chlorophyll a v. Chlorophyll b- Chlorophyll b is an accessory pigment that has a slight structural difference which allows them to absorb slightly different colors (and have different colors). – ________________yellow and orange hydrocarbons CAROTENOIDS that absorb violet and blue-green light. – These can broaden the spectrum of photosynthesis and PHOTOPROTECTION ability to absorb and rid provide __________________: excessive light energy that would damage chlorophyll or interact with oxygen. – Chlorophyll and Light • When a molecule ________________a photon of light, one ABSORBS of the molecule’s electrons is elevated to an orbital where it has more potential energy (from ground state to EXCITED ___________ state). • A compound absorbs only photons that have specific wavelengths which is why each pigment has its UNIQUE ________________ absorption spectrum. CANNOT • The electron ________________ stay in an excited state so will drop to its ground state which releases excess energy as _____________. HEAT • Chlorophyll in isolation will also release light FLUORESCENCE as well as heat. (_____________) • P. 189 Fig. 10.11 • Example: Car roof on a hot day (which is coolest?) • ________________: Reaction Center associated with LightPHOTOSYSTEM Harvesting Complexes – Photosystems are composed of reaction centers surrounded by a number of light-harvesting complexes that consist of PIGMENT ____________ molecules bound to particular ___________. PROTEINS – The number and variety of pigment molecules allow a LARGER photosystem to harvest light over a ________________ surface of the spectrum. – Picture: – • Reaction Center- protein complex that includes two ________________chlorophyll a molecules and a molecule SPECIAL called the primary electron acceptor. • These chlorophyll a molecules, because of their environment enable them to use the energy from light to boost one of HIGHER their electrons to a ________________ energy level. • First step of the light reactions: ___________-powered transfer an electron from the special chlorophyll a molecule SOLAR to the primary electron acceptor (_________ reaction). – Photosystems convert light energy to REDOX chemical energy to be used to ________________ sugar. SYNTHESIZE – The ________________membrane contains two types of THYLAKOID photosystems that cooperate in the light reactions. Photosystem II (PSII) [first] (Chlorophyll a- ______) Photosystem I (PSI) (Chlorophyll a- ______) p680 p700 • Reactions in the Photosystem- Noncyclic electron flow pg190 – – – – Photon of light hits a ________________ in a light harvesting PIGMENT complex and is moved to other pigment molecules until it reaches a P680 molecule in PS II. It excites one of the two P680 molecules. The electron is then ________________by the primary CAPTURED electron acceptor. An enzyme splits a water molecule into two electrons, two H+ ions and ½ O2. Electrons are supplied one by one to the p680 LOST to the primary ________ replacing an electron ______ electron acceptor. Oxygen combines with another oxygen to form O2. Each excited electron passes from the primary electron acceptor of PS II to PS I by an ELECTRON TRANSPORT CHAIN ________________________________. – – – – – – The exergonic “______” of electrons to a lower energy level FALL provides energy for _____ ATP synthesis. At the same time, light energy was ________________by TRANSFERRED a light harvesting complex to the PS I reaction center, exciting an electron of a P700 molecule. The excited electron is then captured by PS I primary electron acceptor, creating an electron “hole” in P700. Hole is filled by an electron that reaches the bottom of the electron transport chain from _________. PS II Excited electrons are passed from PS I’s PRIMARY ELECTRON ACCEPTOR ________________________________ down a electron transport chain through the protein ________________ (Fd). FERRODOXIN The enzyme NADP+ reductase transfers electrons from Fd to REDUCTION NADP+. Two electrons are required for its ________________ to NADPH. Summary: Light reactions use solar power to generate ATP (chemical energy) and NADPH (reducing power) which will fuel the ________________. CALVIN CYCLE non cyclic- good! • – – – – – Reactions in the Photosystem- _____________ electron flow CYCLIC Under certain conditions, photoexcited electrons can take a I but not cyclic electron flow which uses photosystem ___ II photosystem ___. Electrons ______ CYCLE back from ferredoxin (Fd) to the cytochromes complex and back from there on to a P700 in the PS I reaction center. ATP is ______________. GENERATED There is no production of ________________ and no release NADPH OXYGEN of ________________. Why use cyclic electron flow? – Noncyclic electron flow generates an ________________ EQUAL amount of ATP and NADPH but the Calvin cycle uses MORE _________ ATP than NADPH so cyclic electron flow can provide more ATP. – A rise in NADPH can result in shift to cyclic electron flow which allows ATP to catch up to NADPH (_____________________). SUPPLY & DEMAND Cyclic & noncyclic Links! • • • • • cyclic vs non cyclic no narration Cyclic & noncyclic non cyclic- good! non cyclic light rxn Light rxn overview CHLOROPLAST BOTH MITOCHONDRIA photosystems capture light energy and use it to drive electrons to the top of the transport chain. Have ETC in membrane proteins pump proteins across membranes High energy electrons dropped down the transport chain are extracted from organic molecules chloroplast transform light energy into chemical energy in ATP (and NADPH) Electrons pass through progressively more electronegative carriers mitochondria transfer chemical energy from food molecules to ATP (and NADH) CHLOROPLAST BOTH The thylakoid ATP synthase are membrane of the very similar chloroplast pumps protons from the stroma into the thylakoid space (interior of the thylakoid), which functions as the H+ reservoir. The thylakoid membrane makes ATP as the hydrogen ions diffuse down their concentration gradient from the thylakoid space back to the stroma MITOCHONDRIA The inner membrane of the mitochondrion pumps protons from the mitochondrial matrix out of the intermembrane space, which then serves as a reservoir of hydrogen ions that powers the ATP synthase. • – – – – The Calvin Cycle Similar to the citric acid cycle in that a starting material is REGENERATED _________________ after molecules enter and leave the cycle. But while the citric acid cycle is catabolic, the Calvin cycle is ANABOLIC _________________, building sugar from smaller molecules while consuming energy. ______ G3P (glyceraldehyde-3-phosphate) is directly produced from the Calvin Cycle (requires _________ turns of the Calvin 3 Cycle, fixing three molecules of CO2 Phase 1: _________________ CARBON FIXATION • CO2 molecules are fixated one at a time by the enzyme RUBISCO RuBP carboxylase (_________________), attaching to a five carbon sugar, ribulose biphosphate (_________________). RuBP • This produces a six-carbon _________________so unstable INTERMEDIATE that it immediately splits in half, forming two molecules of 3-phosphoglycerate (for each CO2). – Phase 2: _________________ REDUCTION • Each molecule of 3-phosphoglycerate receives an additional phosphate group from ______, becoming 1, 3ATP biphosphoglycerate. NADPH • Next, a pair of electrons donated from ___________ reduces 1, 3-biphosphoglycerate to G3P. Specifically, the electrons from NADPH reduces the carboxyl group of 3phosphoglycerate to the aldehyde group of G3P, which POTENTIAL stores more _____________ energy. • G3P is a sugar—the same three-carbon sugar form in _________________ by the splitting of glucose. GLYCOLYSIS SIX • For every ________ THREE molecules of CO2, there are ______ ONE molecule of this threemolecules of G3P. But only ____ carbon sugar can be counted as a net gain of carbohydrate. • The cycle began with ___ 15 carbons’ worth of carbohydrate in the form of three molecules of the five-carbon sugar _______. RuBP • Now there are ____ 18 carbons’ worth of carbohydrate in the EXITS the cycle form of six molecules of G3P. One molecule ______ to be used by the plant cell, but the other five molecules must be recycled to regenerate the three molecules of RuBP. – Phase 3: _________________ REGENERATION of the CO2 acceptor (RuBP). • With a series of reactions, the carbon skeletons of five molecules of G3P are __________ by the last steps of the REARRANGED Calvin Cycle into three molecules of RuBP. • The cycle spends three more molecules of ATP. The RuBP is now prepared to receive CO2 again, and the cycle continues. • For the net synthesis of one G3P molecule, the Calvin cycle CONSUMES ______________ a total of 9 molecules of ATP and six molecules of NADPH. STARTING • G3P becomes the _________________ molecule for metabolic pathways for other organic compounds. EMERGENT • Photosynthesis is an _________________ property of the chloroplast which integrates both stages (neither could EXIST _________________ on its own). Calvin Cycle Links • • • • Calvin Cycle 1 Calvin Cycle step by step Calvin cycle step by step 2 PS review • – – – – – – Summarizing Photosynthesis’ Significance Sugar in chloroplasts supplies entire plant with chemical energy and carbon skeletons for the _________________of all SYNTHESIS the major organic molecules of plant cells. 50% of organic material made by photosynthesis is consumed MITOCHONDRIA as fuel for cellular respiration in the _________________of plant cells. Sometimes there is a loss of photosynthetic products to _________________ PHOTORESPIRATION Only green cells are autotrophic parts of plant. The rest depends on molecules such as carbohydrates to be transported out of the leaves in the form of SUCROSE _________________. Most plants manage to make more organic fuel than they need to use so they can store it in the form of _________________ STARCH (chloroplasts). OXYGEN Photosynthesis is responsible for the _________________in our atmosphere.