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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece.

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Presentation on theme: "Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece."— Presentation transcript:

1 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Chapter 9 Cellular Respiration: Harvesting Chemical Energy

2 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Quiz 1.Define oxidation. 2.Define reduction. 3.List the four ways an enzyme reduces E A.

3 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Quiz 1.Define oxidation. 1.The gain of an electron resulting in a reduced charge. 2.Define reduction. 1.The loss of an electron resulting in an increased charge. 3.List the four ways an enzyme reduces E A. 1.Orientating the substrate correctly. 2.Stressing the bonds of the substrate 3.Providing the correct chemical environment 4.Covalently bonding to the substrate

4 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cells must work (use nrg) to live Figure 9.1

5 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Review of nrg Cycle Energy – Flows into an ecosystem as sunlight and leaves as heat. – Our cells get nrg from the food we eat. – Turn chemical nrg in food to ATP, CO 2, and H 2 O

6 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Overview of Cellular Respiration An overview of cellular respiration – 3 Phases: Glycolysis* Citric Acid Cycle (AKA Krebs Cycle) Oxidative phosphorylation – Each phase yields some ATP

7 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Key Concepts Both glycolysis and the citric acid cycle – Can generate ATP by substrate-level phosphorylation Figure 9.7 Enzyme ATP ADP Product Substrate P +

8 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Substrate level phosphorylation Enzyme transfers a phosphate group from a substrate to an ADP. – Substrate is an intermediary molecule in Glycolysis or the CAC. Makes only one ATP at a time.

9 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Players: The Victim: Glucose – Gets broken down and has its e - s stolen The Breakers: A posse of enzymes and coenzymes – Will be introduced in each scene The Thieves: Electron Carriers – NAD +, FAD – Carry off electrons to the site of Oxidative Phosphorylation The motive: Make ATP

10 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The scene: A dark stormy night, inside the cell. The action takes place in three areas: 1.Cytosol – Site of Glycolysis. 2.Mitochondrial Matrix – Site of the Citric Acid Cycle. 3.Inner Mitochondrial Membrane (Cristae) – Site of Oxidative phosphorylation.

11 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings An overview of Cellular respiration

12 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 9.2 Scene 1: The cytoplasm Glycolysis – Means splitting of sugar – Breaks down (oxidizes) glucose into pyruvate. – 2 ATP – 2 NAD + – 4 ADP

13 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Glycolysis consists of two major phases – Energy investment phase 5 steps – Energy payoff phase 5 steps

14 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Special Note It is more important that you understand the overall process You will not be examined on the enzymes catalyzing each step of this or the intermediate conformations. However, it is advisable that you know them and are familiar with how the process occurs.

15 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A closer look at the nrg investment phase 1 Glucose + 2 ATP = 2 Glyceraldehyde 3- Phosphate + 2 ADP Glucose gets phosphorylated 2 times. After 2 nd phosphorylaton, Molecule gets split into 2 3-carbon molecules

16 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A closer look at the nrg payoff phase 2 3-Carbon sugar + 2 NAD + +2P i = 2 Pyruvates + 2H 2 O +4 ATP + 2NADH + 2 H + 1.Pyruvates continue into CAC 2.NADH+H + goes to Oxidative phosphorylation. 3.4 ATPs are generated 4.2 waters are generated

17 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 9.3- Scene 2: The mitochondrial Matrix Site of the Citric Acid Cycle Completes the energy-yielding oxidation (breakdown) of organic molecules Key Characters (names you should know): 1.CoEnzyme A 2.Acetyl CoA 3.Oxaloacetate

18 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Pyruvate must first be converted to acetyl CoA using Coenzyme A CYTOSOLMITOCHONDRION NADH + H + NAD CO 2 Coenzyme A Pyruvate Acetyle CoA S CoA C CH 3 O Transport protein O–O– O O C C CH 3 Figure 9.10

19 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

20 Overview of the Citric Acid Cycle (CAC) ATP 2 CO 2 3 NAD + 3 NADH + 3 H + ADP + P i FAD FADH 2 Citric acid cycle CoA Acetyle CoA NADH + 3 H + CoA CO 2 Pyruvate (from glycolysis, 2 molecules per glucose) ATP Glycolysis Citric acid cycle Oxidative phosphorylation Figure 9.11

21 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A closer look at the CAC

22 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A closer look at the CAC

23 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A closer look at the CAC

24 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A closer look at the CAC

25 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Summary CAC: Acetyl CoA + 3NAD + + FAD + ADP + P i Oxaloacetate + 2CO NADH+3H + + ATP + FADH 2

26 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Homework Review: ( )- Oxidative phosphorylation and fermentation Read and outline (9.6) and (overview-10.1 (Photosynthesis)) Exam C7-C10, Monday the 9 th.

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28 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Quiz 1.In CAC, what is the net yield, in terms of ATP and NADH, of one molecule of glucose? 2.What is the molecule to which pyruvate is combined in the fist step of the Citric Acid Cycle? 3.What are the two types of fermentation. 4.Fermentation occurs under _____ conditions.

29 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Quiz In CAC, what is the net yield, in terms of ATP and NADH, of one molecule of glucose? (2 points) 2 ATP and 6 NADH What is the molecule to which pyruvate is combined in the fist step of the Citric Acid Cycle? (2 points) Oxaloacetate List the two types of fermentation. (2 pts) – Alcohol and lactic Acid Fermentation occurs under anaerobic conditions. (1 Point)

30 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 9.4 Act 3 Inner mt Membrane Chemiosmosis couples electron transport to ATP synthesis NADH and FADH 2 from glycolysis and CAC – Donate electrons to the electron transport chain, which powers ATP synthesis via oxidative phosphorylation

31 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings E - gradually lose energy. – (where does it go?) At the end of the chain – Electrons are passed to oxygen, forming water The Pathway of Electron Transport

32 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings At certain steps along the electron transport chain – Pumps H + to the OUTSIDE of the inner membrane. Where actually is this, then, in the mt? What type of transport is this?

33 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The resulting H + gradient – Stores energy – Drives chemiosmosis in ATP synthase – Is referred to as a proton-motive force

34 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Chemiosmosis – Is an energy-coupling mechanism that uses energy (H + gradient) to drive cellular work. In this case, the H + gradient is across the inner mt membrane, Work is making ATP

35 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 3 Processes in this metabolic enterprise

36 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Chemiosmosis and the electron transport chain

37 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Chemiosmosis: The Energy-Coupling Mechanism ATP synthase – Is the enzyme that actually makes ATP

38 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings An Accounting of ATP Production by Cellular Respiration During respiration, most energy flows in this sequence – Glucose to NADH to electron transport chain to proton-motive force to ATP

39 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings About 40% of the energy in a glucose molecule – Is transferred to ATP during cellular respiration, making approximately 38 ATP

40 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings When electrons flow along the electron transport chains of mitochondria, which of the following changes occur? – The pH of the matrix increases. – ATP synthase pumps protons by active transport. – The electrons gain free energy. – The cytochromes of the chain phosphorylate ADP to form ATP. – NAD + is oxidized.

41 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings In the 1940s, some physicians prescribed low doses of a drug called dinitrophenol (DNP) to help patients lose weight. This unsafe method was abandoned after a few patients died. DNP uncouples the chemiosmotic machinery by making the lipid bilayer of the inner mitochondrial membrane leaky to H+. What impact does this have on ATP production? * – reduces substrate level phosphorylations – increases substrate level phosphorylations – reduces oxidative level phosphorylations – increase oxidative level phosphorylations – This would have no impact on ATP production.

42 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Glucose, made from six radioactively labeled carbon atoms, is fed to yeast cells in the absence of oxygen. How many molecules of radioactive alcohol (C 2 H 5 OH) are formed from each molecule of glucose? – 0 – 1 – 2 – 3 – 6

43 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cyanide is a poison that blocks the passage of electrons along the electron transport chain. Which of the following is a metabolic effect of this poison? – The lower pH of the intermembrane space is much lower than normal. – Electrons are passed directly to oxygen, causing cells to explode. – Alcohol would build up in the cells. – NADH supplies would be exhausted, and ATP synthesis would cease. – No proton gradient would be produced, and ATP synthesis would cease.

44 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Which kind of metabolic poison would most directly interfere with glycolysis? – an agent that reacts with oxygen and depletes its concentration in the cell – an agent that binds to pyruvate and inactivates it – an agent that closely mimics the structure of glucose but is not metabolized – an agent that reacts with NADH and oxidizes it to NAD + – an agent that inhibits the formation of acetyl coenzyme A

45 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings You have a friend who lost 15 pounds of fat on a diet. Where did the fat go (how was it lost)? * – It was released as CO 2 and H 2 O. – Chemical energy was converted to heat and then released. – It was converted to ATP, which weighs much less than fat. – It was broken down to amino acids and eliminated from the body. – It was converted to urine and eliminated from the body.


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