BI0 120 cell and tissues - Hanover College



LESSON - 23

ENERGY METABOLISM: THE CHEMOORGMTOTROPHS

THE OXIDATION OF GLUCOSE

A. Objectives

- Explain the oxidation of an organic molecule such as glucose to carbon dioxide and water by glycolysis and Krebs cycle; discuss the steps that result in ATP production by substrate-level phosphorylation; identify the oxidation steps; know the cost of ATP production in terms of coenzyme reduction; characterize the events occurring in each step of the two pathways; locate the site of glycolysis and citric acid cycle in the prokaryotic and eukaryotic cell.

B. Lecture outline

1. OXIDATION OF GLUCOSE: OVERVIEW.

Read: The four stages of aerobic respiration (SBM p173-185)

2. THE GLYCOLYSIS

Read: In glycolysis, glucose yields two pyruvate (SBM p174-178).

a. preparatory reactions

b. oxidation process

C. summary

3. THE CITRIC ACID CYCLE, TRICARBOXYLIC ACID CYCLE OR KREBS CYCLE

Read: Pyruvate is converted to acetyl CoA (SBM p175-178)

The citric acid cyclce oxidizes acetyl CoA (SBM p178-179)

a. introduction of pyruvate into the Krebs cycle

b. Krebs cycle

c. summary

4. BALANCE (Table 9.1 (R&J p199)]

Oxidation of 1 mole of glucose yielded 4 moles of ATP at a cost of 10 moles reduced NADH+H+ and 2 moles reduced FADH2.

C. Study Questions.

1. What event(s) occur(s) during the oxidative breakdown of an organic molecule such as glucose?

A. The organic molecule is broken down in smaller fragments.

B. electrons are freed from the organic molecule.

C. part of the energy that is liberated is trapped in ATP.

D. intermediate electron carriers such as NAD + and FAD are reduced.

E. all of the above.

2. The glycolysis describes

A. energy production from glucose.

B. oxidative breakdown of glucose.

C. oxidative breakdown of glucose into 2 pyruvate molecules.

D. oxidation of pyruvate in the Kreba cycle.

E. ATP synthesis by oxidative phosphorylation.

3. The correct sequence of compounds of the activation phase of the glycolysis is

A. glucose, fructose-1,6-diphosphate, giyceraldehyde-3-phosphate.

B. glucose, giyceraldehyde-3-phosphate, fructose-1, 6-diphosphate.

C. glucose, glyceraldehyde-3-phosphate, pyruvate.

D. glucose, alpha-ketolutarate, succinate.

E. glucose, 1, 3-diphospholycerate, phosphoenolpyruvate.

4. The preparatory or activation phase of the glycolysis include

A. ATP synthesis by substrate-level phosphorylat ion.

B. oxidation of fructose-1,6-diphosphate in glyceraldehyde3-phosphate.

C. reduction of coenzyme I.

D. phosphorylation of glucose and breakdown in 2 glyceraldehyde3-phosphate molecules.

E. oxidative decarboxylation of pyruvate.

5. The molecule that is oxidized during the glycolysis is

A. acetate.

B. pyruvate.

C. phosphoenolpyruvate.

D. 1, 3-diphosphoglycerate.

E. glyceraldehyde-3-phosphate.

6. The energy liberated during the oxidation reaction of the glycolysis is temporarily stored in

A. acetate-phosphate

B. fructose-1,6-diphosphate

C. phosphoenolpyruvate.

D. 1,3-diphosphoglycerate.

E. glyceraldehyde-3-phosphate.

7. What compound accepts the electrons during the oxidation of glyceraldehyde-3-phosphate?

A. 1,3-diphosphoglycerate.

B. coenzyme I.

C. ATP.

D. glyceraldehyde-3-phosphate.

E. pyruvate.

8. How many oxidations occur in the breakdown of glucose by glycolysis?

A. 1.

B. 2.

C. 3.

D. 4.

E. 5.

9. If the reaction: glucose ( x pyruvate + y NADH+H+ + z ATP, summarizes the glycolysis, what are the values of x, y, and z?

X Y Z

A. 1 2 3

B. 3 2 1

C. 2 2 2

D. 1 2 2

E. 2 10 4

10. How many coenzymes are reduced for each ATP produced in the glycolysis?

A. 1.

B. 2.

C. 3.

D. 6.

E. 12.

11. Synthesis of ATP in the glycolysis is by

A. oxidative phosphorylat ion.

B. Electron-transport phosphorylat ion.

C. photophosphorylat ion.

D. substrate-level phosphorylation.

E. chemophosphorylation.

12. The breakdown of pyruvate to acetyl Coenzyme A is a(n)

A. oxidation.

B. reduction.

C. deamination.

D. hydrolysis.

E. oxidative decarboxylation.

13. The oxidative decarboxylation of pyruvate results in

A. acetyl-coenzyme A.

B. acetyl-coenzyme A, and carbon dioxide.

C. acetyl-coenzyme A, carbon dioxide, and reduced coenzyme I

D. acetyl-coenzyme A, carbon dioxide, reduced coenzyme I, and ATP.

E. acetyl-coenzyme A, carbon dioxide, reduced coenzyme I, ATP, and FADH2.

14. What event is NOT a part of the Krebs cycle?

A. Introduction of acetate.

B. Oxidative decarboxylation of citrate.

C. Harvest of energy from succinyl Coenzyme A.

D. Oxidation of glyceraldehyde-3-phosphate.

E. oxidative regeneration of oxaloacetate.

15. Oxaloacetate accepts the 2-carbon fragment to form

A. citrate.

B. alpha-ketoglutarate.

C. succinate.

D. fumarate.

E. oxaloacetate.

16. ATP synthesis occurs in the conversion of

A. oxaloacetate to citrate.

B. citrate to alpha-ketoglutarate.

C. alpha-ketoglutarate to succinylcoenzyme A.

D. succinyl-Coenzyme A to succinate.

E. succinate to fumarate.

17. What reaction is an oxidative decarboxylat ion?

A. oxaloacetate to citrate.

B. alpha-ketoglutarate to succinyl-Coenzyme A.

C. succinyl—coenzyme A to succinate.

D. succinate to fumarate.

E. fumarate to oxaloacetate.

18. What reaction yields FADH2?

A. oxaloacetate to citrate.

B. alpha-ketoglutarate to succinyl-Coenzyme A.

C. succinyl-Coenzyme A to auccinate.

D. succinate to fumarate.

E. fumarate to oxaloacetate.

19. What reaction does NOT constitute an oxidation?

A. citrate to alpha-ketoglutarate.

B. alpha-ketoglutarate to succinylcoenzyme A.

C. succinyl-Coenzyme A to succinate.

C. succinate to fumarate.

D. fumarate to oxaloacetate.

20. What reaction(s) yield(s) carbon dioxide?

A. citrate to alpha—ketoglutarate.

B. alpha-ketoglutarate to succinate.

C. succinate to fumarate.

D. fumarate to oxaloacetate.

E. both A and B.

21. How many molecules of coenzyme I are reduced in one cycle (turn) of the Krebs cycle?

A. 1.

B. 2.

C. 3.

D. 4.

E. 5.

22. How many pairs of electrons are freed in one cycle (turn) of the citric acid cycle?

A. 2.

B. 4.

C. 6.

D. 8.

E. 10.

23. How many times does the Krebs cycle turn to oxidize glucose completely?

A. 1.

B. 2.

C. 3.

D. 4.

E. 5.

24. How many molecules of ATP are generated from 1 molecule of glucose in the citric acid cycle?

A. 1.

B. 2.

C. 3.

D. 4.

E. 5.

25. If the reaction: acetate ————> u carbon dioxide + x NADH+H+ + y FADH2 +z ATP, summarizes the Krebs cycle, what are the values of u, x, y, and z?

| |U |X |Y |Z |

|A |1 |2 |3 |4 |

|B |3 |2 |1 |1 |

|C |2 |3 |1 |2 |

|D |2 |6 |2 |2 |

|E |2 |12 |4 |4 |

26. How many reducing equivalents (NAD+ plus FAD) are required for each ATP molecule produced in the oxidative breakdown of pyruvate?

A. 1.

B. 2.

C. 3.

D. 4.

E. 5.

25. If the reaction: glucose ( u carbon dioxide + x NADH+H+ + yFADH2 + ZATP

summarizes the complete oxidation of glucose, what are the values of u, x, y, and z?

| |U |X |Y |Z |

|A |1 |2 |3 |4 |

|B |6 |2 |1 |1 |

|C |3 |6 |2 |2 |

|D |3 |10 |2 |2 |

|E |6 |10 |2 |4 |

26. The citric acid cycle is responsible for the oxidation of

A. carbon dioxide and water.

B. oxygen.

C. glucose.

D. NAD+ and ATP.

E. acetate.

27. During the oxidative breakdown of glucose, pyruvate is converted into

A. ATP.

B. the citric acid cycle.

C. carbon dioxide and acetyl-Coenzyme A.

E. high-energy bonds.

F. oxidized coenzyme I.

28. The activation phase of the glycolysis consist of

A. adding phosphates, modifying sugars and forming glyceraldehyde-3-phosphate.

B. oxidative steps, proton pumping, and reaction with oxygen.

C. oxidation of glyceraldehyde-3-phosphate, and storage of energy.

D. ATP synthesis by substrate-level phosphorylation, and formation of pyruvate.

E. oxidation of pyruvate, and formation of acetyl-Coenzyme A.

29. The oxidation phase of the glycolysis consists of

A. adding phosphates, modifying sugars and forming glyceraldehyde-3-phosphate.

B. oxidative steps, proton pumping, and reaction with oxygen.

C. oxidation of glyceraldehyde-3-phosphate, and storage of energy.

D. ATP synthesis by substrate-level phosphoryJ.ation, and formation of pyruvate.

E. oxidation of pyruvate, and formation of acetyl—coenzyme A.

30. The energy-harvesting phase of the glycolysis consists of

A. adding phosphates, modifying sugars, and forming glyceraldehyde-3-phosphate.

B. oxidative steps, proton pumping, and reaction with oxygen.

C. oxidation of glyceraldehyde-3-phosphate, and storage of energy.

D. ATP synthesis by substrate-level phosphorylation, and formation of pyruvate.

E. oxidation of pyruvate, and formation of acetyl—coenzyme A.

31. The activation of glucose requires

A. energy in the form of high-energy electrons.

B. the investment of 2 ATP molecules.

C. the cleavage of the glucose to carbon dioxide.

D. the formation of glucose from fructose.

E. the condensation of two glyceraldehyde-3-phosphate molecules into glucose.

32. The sugar-like product of the glycolysis are two molecules of

A. carbon dioxide.

B. citric acid.

C. fructose-1,6-diphosphate.

D. pyruvate.

E. glyceraldehyde-3-phosphate.

33. In addition to modifications of the glucose carbon chain, the glycolytic pathway also results in

A. energy in the form of C-H bonds.

B. energy in the form of C=O bonds.

C. a net yield of 2 ATP molecules.

D. 2 molecules of NAD+

E. several pairs of free electrons.

34. The enzymes responsible for the reactions of the glycolysis occur

A. attached to the electron carrier cytochrome c.

B. bound to the inner surface of the plasma membrane.

C. bound to the inner mitochondrial membrane.

D. bound to vesicles of the endoplasmic reticulum.

E. freely dissolved in the cytoplasm.

35. The removal of carbon dioxide from pyruvate results in

A. 1 molecule of glucose.

B. a 2-carbon molecule, acetate.

C. 2 molecules of carbon dioxide.

D. a molecule of lactic acid.

E. citric acid.

36. Two intermediate electron carriers used in the Krebs cycle are

A. NAD+ and FAD.

B. ATP and ADP.

C. water and oxygen.

D. pyruvate and citrate.

E. 1,3-diphosphoglycerate and phosphoenolpyruvate.

37. The enzymes of the citric acid cycle are contained in the

A. cytoplasm.

B. matrix of the mitochondria.

C. membranes of the rough endoplasmic reticulum.

D. intermembrane space of mitochondria.

E. inner membrane of the chloroplasts.

38. What is the fate of the carbon fragment that proceeds through the citric acid cycle?

A. conversion to heat.

B. synthesis of glucose.

C. it simply disappears.

D. 2 Co2 and H-atoms, which end up in NADH+H+ and FADH2.

E. 6 CO2 and 6 H20.

39. A chemical process during which a substance gains electrons and energy is called:

a. Oxidation.

b. Oxidative phosphorylation.

c. Deamination.

d. Reduction.

e. Dehydrogenation.

40. Which of the following is a correct ranking of molecules with respect to their energy value in glycolysis?

a. Two pyruvate > one glucose.

b. One glucose > on fructose-1,6-bisphosphate.

c. Two glyceraldehydes-3-phosphate > one glucose.

d. Two pyruvates > one fructose.

e. Two pyruvates > two glyceraldehydes-3-phosphate.

41. The reactions of the _______ take place within the cytosol of eukaryotic cells.

a. Glycolysis.

b. Oxidation of pyruvate.

c. Citric acid cycle.

d. Chemiosmosis.

e. Electron transport chain.

42. Before pyruvate enters the TCA cycle, it is decarboxylated, oxidized, and combined with coenzyme A, forming acetyl CoA, carbon dioxide, and one molecule of

a. NADH + H+

b. FADH2

c. ATP

d. ADP

e. C6H12O6

43. In the first step of the CTA, acetyl CoA reacts with oxaloacetate to form

a. Pyruvate.

b. NADH + H+

c. ATP.

d. Citrate.

e. CO2

True/False

44. For each glucose molecule that begins cellular respiration, the citric acid cycle must turn once. _____

45. For each acetyl CoA molecule that enters the citric acid cycle, two CO2 molecules are produced. ______

46. An example of an anabolic reaction is the hydrolysis of a polysaccharide into monosaccharides. ______

47. The reactions of the TCA cycle take place in the matrix o the mitochondria. ______

48. In the TCA cycle, oxaloacetate rfeacts with acetyl CoA forming citrate. _______

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download