Chapter 9 Cellular Respiration Copyright Pearson Prentice Hall
9-1 Chemical Pathways Both plant and animal cells carry out the final stages of cellular respiration in the mitochondria. Animal Cells Animal Mitochondrion Plant Plant Cells
Chemical Energy and Food One gram of glucose (C6H12O6), when burned in the presence of oxygen, releases 3811 calories of heat energy. A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius.
Overview of Cellular Respiration Cellular respiration is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen. Matrix Intermembrane Space
Overview of Cellular Respiration* The equation for cellular respiration is: 6O 2 + C 6 H 12 O 6 6CO 2 + 6H 2 O + Energy oxygen + glucose carbon dioxide + water + Energy
Overview of Cellular Respiration* Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport take place in the mitochondria. Glycolysis Cytoplasm Mitochondrion
Glycolysis* ATP Production At the beginning of glycolysis, the cell uses up 2 molecules of ATP to start the reaction. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2 Pyruvic acid
Glycolysis* When glycolysis is complete, 4 ATP molecules have been produced. This gives the cell a net gain of 2 ATP molecules. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2 Pyruvic acid
Glycolysis Remember from Photosynthesis? High energy electron carrier NADP+ Cellular respiration uses different carriers to transport high energy electrons. NAD+ FAD
Glycolysis NADH Production One molecule of glucose (6 carbons) is split into two molecules of pyruvic acid (3 carbons). Requires energy in the form of ATP. Yields 2 ATP Yields 2 NADH 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2NAD + 2
Glycolysis* The Advantages of Glycolysis The process of glycolysis is so fast that cells can produce thousands of ATP molecules in a few milliseconds. Glycolysis does not require oxygen.
Fermentation* When oxygen is not present, glycolysis follows a different pathway, called fermentation. producing ATP in the absence of oxygen.
Fermentation Fermentation does not require oxygen it is an anaerobic process. Two main types of fermentation.
Fermentation* Alcoholic Fermentation Yeasts and a few other microorganisms use alcoholic fermentation, forming ethyl alcohol and carbon dioxide as wastes. pyruvic acid + NADH alcohol + CO2 + NAD+
Fermentation* Lactic Acid Fermentation Pyruvic acid that accumulates as a result of glycolysis can be converted to lactic acid. pyruvic acid + NADH lactic acid + NAD+
9.1 Concept Assessment 1. Describe the process of cellular respiration. 2. Key Concept What are the products of glycolysis? 3. Key Concept Name the two main types of fermentation. 4. What is a calorie? A Calorie? 5. How is the function of NAD + similar to that of NADP +? 6. Critical Thinking Comparing and Contrasting How are lactic acid fermentation and alcoholic fermentation similar? How are they different?
9.1 QUIZ
9.1 Vocab calorie glycolysis cellular respiration NAD+ (nicotinamide adenine dinucleotide) fermentation anaerobic
1- The raw materials required for cellular respiration are Quiz 9.1 A. carbon dioxide and oxygen. B. glucose and water. C. glucose and oxygen. D. carbon dioxide and water.
Quiz 9.1 2- Glycolysis occurs in the A. mitochondria. B. cytoplasm. C. nucleus. D. chloroplasts
3- The net gain of ATP molecules after glycolysis is Quiz 9.1 A. 3 ATP molecules. B. 2 ATP molecules. C. 3 pyruvic acid molecules. D. 4 pyruvic acid molecules
Quiz 9.1 4- Fermentation releases energy from food molecules in the absence of A. oxygen. B. glucose. C. NADH. D. alcohol.
5- The two main types of fermentation are called Quiz 9.1 A. alcoholic and lactic acid. B. lactic acid and anaerobic. C. aerobic and anaerobic. D. alcoholic and aerobic.
Quiz 9.1 6- Which of the following acts as an electron carrier in cellular respiration? A. NAD+ B. pyruvic acid C. ATP D. ADP
7- Which of the following is NOT a product of glycolysis? Quiz 9.1 A. NADH B. pyruvic acid C. ATP D. glucose
Quiz 9.1 8- One cause of muscle soreness is A. alcoholic fermentation. B. the Krebs cycle. C. glycolysis D. lactic acid fermentation
Quiz 9.1 9- The starting molecule for glycolysis is A. pyruvic acid. B. glucose. C. ADP D. citric acid
10- Which of these is a product of cellular respiration? Quiz 9.1 A. glucose. B. oxygen. C. water D. all of the above
9-2 The Krebs Cycle In the presence of oxygen, Krebs cycle begins when pyruvic acid produced by glycolysis enters the mitochondrion.
The Krebs Cycle
The Krebs Cycle Pyruvic acid from glycolysis is converted into a usable form, Acetyl CoA.
The Krebs Cycle One carbon molecule is removed, forming CO2, and electrons are removed, changing NAD+ to NADH.
The Krebs Cycle Acetyl-CoA then adds the 2-carbon acetyl group to a 4-carbon compound, forming citric acid.
The Krebs Cycle Citric acid is broken down into a 5-carbon compound, then into a 4-carbon compound.
The Krebs Cycle Two more molecules of CO2 are released and electrons join NAD+ and FAD, forming NADH and FADH2
The Krebs Cycle In addition, one molecule of ATP is generated.
The Krebs Cycle
The Krebs Cycle The energy tally from 1 molecule of pyruvic acid is 4 NADH 1 FADH 2 1 ATP 3 CO 2
The Krebs Cycle Happens if oxygen is present. Pyruvates break down further so that the carbon and oxygen atoms end up in CO2.
The Krebs Cycle Hydrogens and electrons are stripped and loaded onto NAD+ and FAD to produce NADH and FADH2 2 more ATP produced, but loads several electron carriers that will be used in the 3rd stage.
Electron Transport The electron transport chain uses the highenergy electrons from the Krebs cycle to convert ADP into ATP.
Electron Transport High-energy electrons from NADH and FADH 2 are passed along the electron transport chain from one carrier protein to the next.
Electron Transport At the end of the chain, an enzyme combines these electrons with hydrogen ions and oxygen to form water.
Electron Transport As the final electron acceptor of the electron transport chain, oxygen gets rid of the lowenergy electrons and hydrogen ions.
Electron Transport When 2 high-energy electrons move down the electron transport chain, their energy is used to move hydrogen ions (H+) across the membrane.
Electron Transport During electron transport, H+ ions build up in the intermembrane space, so it is positively charged.
Electron Transport The other side of the membrane, from which those H+ ions are taken, is now negatively charged.
Electron Transport
Electron Transport As H+ ions escape through channels, the ATP synthase spins. Channel ATP synthase
Electron Transport As it rotates, the enzyme grabs a lowenergy ADP, attaching a phosphate, forming high-energy ATP. Channel ATP synthase ATP
The Totals The breakdown of glucose through cellular respiration, including glycolysis, results in the production of 36 molecules of ATP.
The Totals
The Totals Cells contain small No of ATP produced during glycolysis and cellular respiration. In a quick exercise muscles contain only enough of this ATP for a few seconds. That store of ATP is quickly gone. At this point, muscle cells are producing most of their ATP by lactic acid fermentation. That will last about 90 seconds. The only way to get rid of lactic acid is in a chemical pathway that requires extra oxygen. To repay, you have to do plenty of heavy breathing to get the O2. For anything longer cellular respiration is the only way to generate a continuing supply of ATP. Cellular respiration releases energy slower than fermentation, which is why even well-conditioned athletes have to pace themselves during a
9.2 Concept Assessment 1. What happens to pyruvic acid during the Krebs cycle? 2. How does the electron transport chain use the high-energy electrons from the Krebs cycle? 3. Why is cellular respiration considered to be much more efficient than glycolysis alone? 4. How many molecules of ATP are produced in the entire breakdown of glucose? 5. Compare the energy flow in photosynthesis to the energy flow in cellular respiration. 6. How is the chemical energy in glucose similar to money in a savings account?
9.2 Quiz
9.2 Quiz 1. The Krebs cycle breaks pyruvic acid down into A. oxygen. B. NADH. C. carbon dioxide. D. alcohol.
9.2 Quiz 2. What role does the Krebs cycle play in the cell? A. It breaks down glucose and releases its stored energy. B. It releases energy from molecules formed during glycolysis. C. It combines carbon dioxide and water into highenergy molecules. D. It breaks down ATP and NADH, releasing stored energy.
9.2 Quiz 3. In eukaryotes, the electron transport chain is located in the A. cell membrane. B. inner mitochondrial membrane. C. cytoplasm. D. outer mitochondrial membrane.
9.2 Quiz 4. To generate energy over long periods, the body must use A.stored ATP. B.lactic acid fermentation. C. cellular respiration. D.glycolysis
9.2 Quiz 5. Which statement correctly describes photosynthesis and cellular respiration? A. Photosynthesis releases energy, while cellular respiration stores energy. B. Photosynthesis and cellular respiration use the same raw materials. C. Cellular respiration releases energy, while photosynthesis stores energy. D. Cellular respiration and photosynthesis produce the same products.
9.2 Quiz 6. The Krebs cycle starts with A. glucose and yields 32 ATPs. B. pyruvic acid and yields carbon dioxide. C. pyruvic acid and yields lactic acid or alcohol. D. lactic acid and yields carbon dioxide.
9.2 Quiz 7. The starting molecule for the Krebs cycle is A. NADH B. coenzyme C. pyruvic acid. D. glucose.
9.2 Quiz 8. The Krebs cycle produces A. glucose B. lactic acid C. electron carriers D. oxygen
9.2 Quiz 9. Photosynthesis is to chloroplasts as cellular respiration is to A. chloroplasts B. nuclei C. bytoplasm D. mitochondria
9.2 Quiz 10. The Krebs cycle does not occur if A. glycolysis occurs B. carbon dioxide is present C. oxygen is present D. fermentation occurs
9.2 Quiz 11. Which of the following is the correct sequence of events in cellular respiration? A. Krebs cycle - glycolysis - electron transport B. glycolysis - fermentation - Krebs cycle C. Krebs cycle - electron transport - glycolysis D. glycolysis - Krebs cycle - electron transport
9.2 Quiz 12. Cellular respiration is called an aerobic process because it requires A. exercise B. light C. glucose D. oxygen
Chapter 9 Test