Cellular Respiration Chapters 8-10

Warm Up Exercise Explain the difference between competitive and noncompetitive inhibitorsExplain the difference between competitive and noncompetitive inhibitors Describe the negative feedback demonstrated by ATP/ADP.Describe the negative feedback demonstrated by ATP/ADP.

Cellular Respiration

Cell respiration is a catabolic pathway.Cell respiration is a catabolic pathway. Aerobic Cellular RespirationAerobic Cellular Respiration Anaerobic Cellular Respiration (aka: Fermentation)Anaerobic Cellular Respiration (aka: Fermentation)

Cellular Respiration Organic compounds possess potential energy as a result of their arrangement of atomsOrganic compounds possess potential energy as a result of their arrangement of atoms Fermentation – partial degradation of sugars that occur without OxygenFermentation – partial degradation of sugars that occur without Oxygen Aerobic Respiration – most prevalent and efficient catabolic pathway (Oxygen is consumed)Aerobic Respiration – most prevalent and efficient catabolic pathway (Oxygen is consumed)

Cellular Respiration Most eukaryotic and many prokaryotic can carry out aerobic respirationMost eukaryotic and many prokaryotic can carry out aerobic respiration Some prokaryotes can use substances other than oxygen as reactants – anaerobic respirationSome prokaryotes can use substances other than oxygen as reactants – anaerobic respiration

Cellular Respiration Cellular Respiration uses both aerobic and anaerobic processesCellular Respiration uses both aerobic and anaerobic processes However, usually refers to aerobic processesHowever, usually refers to aerobic processes

Cellular Respiration C 6 H 12 O 6 +6O 2 -> 6 CO H 2 O+ Energy (ATP +Heat)

Cellular Respiration Catabolic processes do not directly do the work; instead, catabolism is linked to work by chemical drive shaft – ATPCatabolic processes do not directly do the work; instead, catabolism is linked to work by chemical drive shaft – ATP Require the regeneration of ATP… This is where Cellular Respiration comes into playRequire the regeneration of ATP… This is where Cellular Respiration comes into play

Redox Reactions How do the catabolic pathways that decompose glucose yield energy???How do the catabolic pathways that decompose glucose yield energy???

Redox Reactions How do the catabolic pathways that decompose glucose yield energy???How do the catabolic pathways that decompose glucose yield energy??? Due to the transfer of electrons during the chemical reaction.Due to the transfer of electrons during the chemical reaction. Relocation of electrons releases energy stored in organic molecules and this energy is used to synthesize ATPRelocation of electrons releases energy stored in organic molecules and this energy is used to synthesize ATP

Redox Reactions Reduction vs. OxidationReduction vs. Oxidation Why are carbs and fats the best molecules for energy?Why are carbs and fats the best molecules for energy? Why must glucose be broken down in a series of steps rather than one quick reaction?Why must glucose be broken down in a series of steps rather than one quick reaction?

Redox Reactions Generally, there exists a transfer of one or more electrons from one reactant to anotherGenerally, there exists a transfer of one or more electrons from one reactant to another This transfer leads to what is called an oxidation – reduction reaction (Redox)This transfer leads to what is called an oxidation – reduction reaction (Redox)

Redox Reactions Oxidation – loss of electrons from one substanceOxidation – loss of electrons from one substance Reduction – addition of electrons to another substanceReduction – addition of electrons to another substance Adding electronsAdding electrons Negatively charged electrons added to atom reduce amount of positive charge of that atomNegatively charged electrons added to atom reduce amount of positive charge of that atom

Redox Reactions Reducing Agent – Electron donorReducing Agent – Electron donor Oxidizing agent – Electron acceptorOxidizing agent – Electron acceptor Transfer is ONLY between the Reactants in a chemical equationTransfer is ONLY between the Reactants in a chemical equation Is this an ionic or covalent bond?Is this an ionic or covalent bond?

REDOX Reaction

Electron Transport Dehydrogenase - removes electrons from glucose (or other substrate) transferring them to its coenzyme (NAD+) which is reduced to NADH. (NADH = potential energy) Dehydrogenase - removes electrons from glucose (or other substrate) transferring them to its coenzyme (NAD+) which is reduced to NADH. (NADH = potential energy) NAD+ (nicotinamide adenine dinucleotide)- an electron carrier. NAD+ (nicotinamide adenine dinucleotide)- an electron carrier. Cycles between NAD+ and NADHCycles between NAD+ and NADH

NAD to NADH

NAD + is one of the most versatile electron acceptors in cellular respiration and functions in several redox steps during the breakdown of glucoseNAD + is one of the most versatile electron acceptors in cellular respiration and functions in several redox steps during the breakdown of glucose This is due to the fact that electrons lose very little of their potential energy when they are transferred from glucose to NAD+This is due to the fact that electrons lose very little of their potential energy when they are transferred from glucose to NAD+ NADH represents stored energy that can be used to make ATPNADH represents stored energy that can be used to make ATP

Electron Transport As glucose is broken down (in many small reactions) electrons are shuttled (by NADH) down the Electron Transport Chain (ETC).As glucose is broken down (in many small reactions) electrons are shuttled (by NADH) down the Electron Transport Chain (ETC). ETC is used to break the fall of electrons to Oxygen into several energy-releasing stepsETC is used to break the fall of electrons to Oxygen into several energy-releasing steps ETC has many molecules (mostly proteins) built into the inner membrane of mitochondria of eukaryotic cells and the plasma membrane of aerobically respiring prokaryotesETC has many molecules (mostly proteins) built into the inner membrane of mitochondria of eukaryotic cells and the plasma membrane of aerobically respiring prokaryotes Ultimately, oxygen is the final electron acceptor.Ultimately, oxygen is the final electron acceptor.

Electron Transport Electrons removed from glucose are shuttled by NADH to the “top”, higher- energy end of the chain.Electrons removed from glucose are shuttled by NADH to the “top”, higher- energy end of the chain. At the “bottom”, lower-energy end of the chain O awaitsAt the “bottom”, lower-energy end of the chain O awaits Ultimately, oxygen is the final electron acceptor.Ultimately, oxygen is the final electron acceptor.

Electron Transport Electron transfer from NADH to O is exergonic with free-energy change of -53 kcal / mol.Electron transfer from NADH to O is exergonic with free-energy change of -53 kcal / mol. Instead of one with one big step and a greater loss of energy, electrons cascade down the chain from one carrier molecules to the next in series of redox reactionsInstead of one with one big step and a greater loss of energy, electrons cascade down the chain from one carrier molecules to the next in series of redox reactions Lose a small amount of energy with each stepLose a small amount of energy with each step

Electron Transport Each downhill carrier is more electronegativeEach downhill carrier is more electronegative Is it oxidizing or reducing it’s “uphill” neighbor?Is it oxidizing or reducing it’s “uphill” neighbor?

Electron Transport Each downhill carrier is more electronegativeEach downhill carrier is more electronegative Is it oxidizing or reducing it’s “uphill” neighbor?Is it oxidizing or reducing it’s “uphill” neighbor? Oxidizing it’s uphill neighborOxidizing it’s uphill neighbor Overall process:Overall process: Glucose-> NADH -> ETC -> OxygenGlucose-> NADH -> ETC -> Oxygen

Warm Up Exercise What is the function of NAD+?What is the function of NAD+? Explain the terms oxidation and reduction.Explain the terms oxidation and reduction. What is the difference between aerobic and anaerobic respiration?What is the difference between aerobic and anaerobic respiration?

What the Stages of Respiration? On a piece of paper, list the stages of cellular respiration and list where each stage occurs. When you are finished turn it into the tray. On a piece of paper, list the stages of cellular respiration and list where each stage occurs. When you are finished turn it into the tray.

Stages of Respiration Glycolysis (in cytoplasm)- can occur with or without oxygen. Glycolysis (in cytoplasm)- can occur with or without oxygen. Pyruvate Oxidation (in mitochondria) Pyruvate Oxidation (in mitochondria) Citric Acid Cycle (in mitochondria) Citric Acid Cycle (in mitochondria) Oxidative Phosphorylation: Electron Transport Chain and Chemiosmosis (in the outer membrane of the mitochondria) Oxidative Phosphorylation: Electron Transport Chain and Chemiosmosis (in the outer membrane of the mitochondria)

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Stages of Respiration Glycolysis (in cytoplasm)- catabolic Glycolysis (in cytoplasm)- catabolic Citric Acid Cycle (catabolic) Citric Acid Cycle (catabolic) Oxidative Phosphorylation: Electron Transport Chain and Chemiosmosis (in the outer membrane of the mitochondria) Oxidative Phosphorylation: Electron Transport Chain and Chemiosmosis (in the outer membrane of the mitochondria)

Stages of Respiration Glycolysis (in cytoplasm)- begins process by breaking down glucose into two molecules of pyruvate Glycolysis (in cytoplasm)- begins process by breaking down glucose into two molecules of pyruvate Citric Acid Cycle in mitochondrial matrix – completes breakdown of glucose by oxidizing a derivative of pyruvate to carbon dioxide Citric Acid Cycle in mitochondrial matrix – completes breakdown of glucose by oxidizing a derivative of pyruvate to carbon dioxide Oxidative Phosphorylation: Electron Transport Chain and Chemiosmosis powered by the redox reactions of the ETC Oxidative Phosphorylation: Electron Transport Chain and Chemiosmosis powered by the redox reactions of the ETC

ADP to ATP Oxidative Phosphorylation - inorganic phosphate is added to ADP to produce ATP. Oxidative Phosphorylation - inorganic phosphate is added to ADP to produce ATP. Occurs in ETC and chemiosmosis.Occurs in ETC and chemiosmosis. Accounts for 90% of the ATP generated by respirationAccounts for 90% of the ATP generated by respiration Substrate-Level Phosphorylation - an enzyme transfers a phosphate group from a substrate molecule to ADP to form ATP. Substrate-Level Phosphorylation - an enzyme transfers a phosphate group from a substrate molecule to ADP to form ATP. Occurs in glycolysis and citric acid cycle.Occurs in glycolysis and citric acid cycle. Substrate = an organic molecule generated as an intermediate in glycolysis. Substrate = an organic molecule generated as an intermediate in glycolysis.

Glycolysis Sugar –splittingSugar –splitting 6C sugar is split into two 3C sugars6C sugar is split into two 3C sugars Can be divided into 2 phases: energy investment and energy payoffCan be divided into 2 phases: energy investment and energy payoff Energy investment – cell actually spends payoffEnergy investment – cell actually spends payoff Payoff – substrate- level phosphorylation produces ATP and reduction of NADPayoff – substrate- level phosphorylation produces ATP and reduction of NAD Net Yield:Net Yield: 2 ATP2 ATP 2 NADH2 NADH

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Warm Up Exercise Without using your notes, name the four major processes of cellular respiration and where in the cell they occur.Without using your notes, name the four major processes of cellular respiration and where in the cell they occur. Explain the difference between oxidative and substrate- level phosphorylation.Explain the difference between oxidative and substrate- level phosphorylation.

Oxidative Phosphorylation Pyruvate enters mitochondria (via active transport) and is converted to Acetyl CoAPyruvate enters mitochondria (via active transport) and is converted to Acetyl CoA

Citric Acid/ Kreb’s Cycle

Acetyl CoA (from oxidative phosphorylation) enters the Citric Acid cycle and combines with oxaloacetate to form citrate, the ionized form of citric acid.Acetyl CoA (from oxidative phosphorylation) enters the Citric Acid cycle and combines with oxaloacetate to form citrate, the ionized form of citric acid.

Warm Up Exercise Walk through the Kreb’s cycle, stating the reactants and the products and where they came from, or go toWalk through the Kreb’s cycle, stating the reactants and the products and where they came from, or go to

ETC Cytochromes - electron carriers in ETC. They are proteins with a Heme group attached. Cytochromes - electron carriers in ETC. They are proteins with a Heme group attached. Represent a series of redox reactions.Represent a series of redox reactions.

Chemiosmosis Chemiosmosis - energy coupling mechanism that uses H+ gradient to drive cellular work. Chemiosmosis - energy coupling mechanism that uses H+ gradient to drive cellular work. ATP Synthase - enzyme that makes ATP from ADP in the inner membrane of mitochondria. ATP Synthase - enzyme that makes ATP from ADP in the inner membrane of mitochondria.

Chemiosmosis Proton Motive Force - the H+ gradient that results from the pumping of H+ ions from the matrix of the mitochondria to the intermembrane space. Proton Motive Force - the H+ gradient that results from the pumping of H+ ions from the matrix of the mitochondria to the intermembrane space.

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Energy Totals Kh;Kh;

Warm Up -Cell Resp Challenge- Why does NADH have more energy than FADH 2 ?Why does NADH have more energy than FADH 2 ? Explain the idea of energy coupling that occurs in chemiosmosis.Explain the idea of energy coupling that occurs in chemiosmosis. What element (atom) helps to pull electrons down the ETC?What element (atom) helps to pull electrons down the ETC? How many total ATPs are produced per molecule of glucose in aerobic respiration?How many total ATPs are produced per molecule of glucose in aerobic respiration?

Alternatives to Aerobic Respiration Anaerobic Respiration - uses ETC with a different final electron receptor (besides oxygen) Anaerobic Respiration - uses ETC with a different final electron receptor (besides oxygen) Fermentation - no ETC. Glycolysis followed by a fermentation process. Fermentation - no ETC. Glycolysis followed by a fermentation process. Two main types: Alcoholic and Lactic AcidTwo main types: Alcoholic and Lactic Acid

Fermentation Alcoholic Fermentation - pyruvate is converted to acetaldehyde then to ethanol (ethyl alcohol). CO 2 byproduct. Alcoholic Fermentation - pyruvate is converted to acetaldehyde then to ethanol (ethyl alcohol). CO 2 byproduct.

Fermentation Lactic Acid Fermentation - pyruvate is reduced by NADH to form lactate, with no release of CO 2. Lactic Acid Fermentation - pyruvate is reduced by NADH to form lactate, with no release of CO 2.

Aerobic vs. Anaerobic Obligate Anaerobes - organisms that cannot survive in the presence of oxygen. Obligate Anaerobes - organisms that cannot survive in the presence of oxygen. Carry out only fermentation or anaerobic respiration.Carry out only fermentation or anaerobic respiration. Facultative Anaerobes - organisms that can survive using fermentation or respiration. Facultative Anaerobes - organisms that can survive using fermentation or respiration.