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AS.020.305 Chapter 9: Exam 2 Notes (dragged) 17

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School
JHU
Department
AS Biology
Course
AS.020.305
Professor
Coppola

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Document Summary

3 steps of glycolysis: add phosphoryl groups to the glucose, chemically convert phosphorylated intermediates into compounds with high phosphate group-transfer potentials, chemically couple the subsequent hydrolysis of reactive substances to atp systhesis. A preparatory stage in which the hexose glucose is phosphorylated and cleaved to yield 2 molecules of triose glyceraldehyde-3-phosphate. This process uses two atps in a kind of energy investment. The molecules of glyceraldehyde-3-phosphate are converted to pyruvate, with concomitant generation of four atps per glucose. Stage a consumes 2 atps, stage b produces 4 atps. Glucose + 2 nad+ + 2 adp + 2 pi ----> 2 nadh + 2 pyruvate + 2 atp + 2h2o + 4h+ From the above equation, it is obvious that 2nad+ is a necessary ingredient required in glycolysis. There are 2 ways to generate nad+: under aerobic conditions, the mitochondrial oxidation of each nadh to nad+ yields three. Atps: under anaerobic conditions, nad+ is regenerated when nadh reduces pyruvate to lactate.

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Related Questions

1. C6H12O6 + 6O2 Ã 6CO2 + 6H2O Glucose is being _____ to _____ and oxygen is being _____ to _____. a. oxidized; carbon dioxide; reduced; water b. oxidized; water; reduced; carbon dioxide Incorrect c. reduced; water; oxidized; carbon dioxide d. reduced; carbon dioxide; oxidized; water

2. Which of the following stages in the breakdown of the piece of toast you had for breakfast generates the most ATP? a. the citric acid cycle Incorrect b. glycolysis c. the digestion of starch to glucose d. oxidative phosphorylation

3. Which of the following is a catabolic pathway? a. gluconeogenesis b. production of starch Incorrect c. glycolysis d. production of glycogen

4. Per molecule, the oxidation of a fatty acid results in _____ energy storage than the oxidation of glucose. a. the same b. less Incorrect c. more d. None of the above; fatty acids cannot be oxidized.

5. Of the eight reactions in the citric acid cycle, how many are oxidation-reduction reactions? a. one b. two c. three d. four e. five

6. The process of glycolysis transfers the energy in sugar molecules into the stored energy of activated carriers such as ATP and NADH. Which statement is true about glycolysis? a. Only eukaryotic organisms do glycolysis. b. The ten reactions of glycolysis are identical in all eukaryotic cells, but are different in prokaryotic cells due to their diverse metabolic strategies. Incorrect c. The ten reactions of glycolysis are identical in almost all living organisms on the planet. d. There are many ways to oxidize glucose and transfer energy into activated carriers; the diversity of organisms on the planet is reflected in the diversity of their mechanisms of glycolysis.

7. Referring to the sentence completed in #13 above, the purpose of the latter reaction (in active muscle cells) is to _____. a. accumulate lactic acid in the cell, which provides additional energy for the production of ATP Incorrect b. slow down glycolysis until oxygen becomes available again c. accelerate the Krebs cycle, which will restore the oxygen supply d. regenerate NAD+ so that glycolysis can continue in the absence of oxygen

8. What are the products of the citric acid cycle? a. carbon dioxide, NADH, FADH2 and GTP b. carbon dioxide, NAD+, FAD and GTP c. NADH, FADH2, and acetyl CoA Incorrect d. carbon dioxide and water

9. Which statement is true about enzymes? a. Enzymes catalyze chemical reactions because they make inherently endergonic reactions exergonic. b. Each enzyme in a cell can catalyze many different chemical reactions involving chemically different substrates. Incorrect c. Enzymes can only catalyze reactions in one direction. d. After catalyzing a reaction, an enzyme is permanently altered and can no longer bind substrate. e. None of the above is true. 1

10. ∆G measures the change in free energy in a system as it converts reactant (Y) into product (X). When [X] = [Y], ∆G is equal to _____. a. RT b. ΔG° + RT c. ΔG° d. ln [X]/[Y]

11. The ∆G° for the hydrolysis of ATP is -7.3 kcal/mol. What conditions in the cell would lead to a ∆G for ATP hydrolysis of -11 kcal/mol? a. An increase in the ATP/ADP ratio b. An increase in anabolic activity in the cell c. Transport of ATP out of the compartment where the reaction is occurring Incorrect d. A decrease in the ATP/ADP ratio

12. In the first reaction of glycolysis, a phosphate transferred from ATP to a glucose molecule to produce glucose-6-phosphate and ADP. Under conditions existing in the cell, the free energy change for this reaction is -8.0 kcal/mole. Which of the following statements is true? Recall that the ∆G° for the hydrolysis of ATP is -7.3 kcal/mol. a. Glucose concentrations in the cell are always low, making this reaction more favorable than would be expected. b. This reaction is less favorable than would be expected, given the ∆G° of ATP hydrolysis. c. Glucose-6-P concentrations in the cell are very low relative to glucose concentrations, making the reaction more favorable than would be expected. d. The ∆G° for the addition of a phosphate to glucose must be -0.7 kcal/mole.

13. Protein E can bind to two different proteins, S and I. The binding reactions are described by the following equations and values: E + S --> ES Keq for ES = 10 E + I> EI Keq for EI = 2 Given the equilibrium constant values, which one of the following statements is true? a. When S is present in excess, no I molecules will bind to E. b. E binds I more tightly than S. c. The binding energy of the ES interaction is greater than that of the EI interaction. d. Changing an amino acid on the binding surface of I from a basic amino acid to an acidic one will probably make the free energy of association with E more negative.

1

Living systems can be studied by way of the scientific method which involves which of the following?

A

Using only deductive reasoning and not inductive reasoning

B

Using few subjects, but repeating the experiments and using controls

C

Using few subjects, but repeating the experiments

D

Using many subjects, but doing no statistical analysis

E

Using many subjects but having no controls

2

Which of the following molecules has the least amount of energy that you can use for intense physical exercise?

A

A chemically specifically designed to signal uncontrolled cell growth

B

Water since it promotes all chemical reactions

C

Lipids

D

Carbohydrates

E

Protein

3

Nicotine produced in plants can be lethal to insects in that it causes a paralysis. Where does nicotine have its effect?

A

Nicotine receptors located in the nucleus of the cell

B

Nicotine receptors on the plasma membrane of brain cells

C

Nicotine receptors in the golgi bodies of neurons

D

Nicotine receptors on the mitochondria of brain cells

4

The aqueous (water) space between cells is which of the following?

A

Blood

B

Interstitial

C

Extracellular

D

Intracellular

E

All of these answers are correct

5

A hypo-osmotic solution can be defined as which of the following?

A

A solution separated from another by way of semipermeable membrane in which the hyposmotic solution has less electrolyes and more water than the other solution

B

A solution separated from another by way of semipermeable membrane in which the hyperosmotic solution has less electrolyes and more water than the other solution

C

A solution that is equal in concentration compared to another

D

A solution that is less concentrated relative to another

E

A solution that is more concentrated relative to another

6

Lactic acid in your muscles is the byproduct of which metabolic pathway?

A

Glycolysis

B

Electron Transport System

C

Krebs cycle

D

Glycolysis and oxygen

7

Which of the following best describes the process of glycolysis?

A

A series of chemical reactions in the mitochondria that breakdown or catabolize glucose to produce ATP without oxygen

B

A series of chemical reactions that breakdown or catabolize protein to produce lactic acid in the presence of oxygen

C

A series of chemical reactions in the muscle cytoplasm that breaksdown or catabolize glucose to produce ATP without oxygen

D

A series of chemical reactions that produce enzymes

8

During oxidative phosphorylation, which of the following is phosphorylated with the assistance of ATP synthase?

A

Cytochromes

B

ADP

C

ATP

D

NADH

E

Hydrogen ions

9

In all animals who use oxidative phorphorylation to generate ATP, the ultimate electron acceptor is directly transported to all cells by way of which of the following?

A

Hemoglobin

B

Red blood cells

C

Water (H2O)

D

Lungs

10

After NADH is reduced at the Electron Transport system, the hydrogen ion subsequently does which of the following?

A

Activates ATPsynthase

B

Activates Krebs cycle

C

Activates chemiosmosis

D

Oxidizes ATP

E

Reduces ATP

11

Which of the following has to exist for ATP synthase to be activated to directly produce ATP?

A

An oxygen gradient

B

A neutron gradient

C

An electron gradient

D

A proton gradient

E

All of these answers are correct

12

Which of the following occurs when oxyhemoglobin reaches the capillaries of heart muscle?

A

Releases oxygen which leaves the capillary and diffuses into the cell

B

Absorbs oxygen from the mitochondria

C

Releases its oxygen which diffuses from the mitochondria to the capillary

D

Releases its oxygen which diffuses from the capillary to the nucleus

1. Which statement comparing chloroplasts and mitochondria is true?

Chloroplasts and mitochondria each contain two membranes.

None of these statements are true.

Chloroplasts pump protons outside the organelle, while mitochondria pump protons inside the inner part of the organelle.

Chloroplasts and mitochondria use electrons from NADH to create a proton gradient.

Chloroplasts and mitochondria use energy from a proton gradient to make ATP.

2. Approximately how many more ATPs are made from one glucose molecule under aerobic conditions with oxidative phosphorylation than under anaerobic conditions?

104

0

2

30

3. As a cyclic pathway, why doens't the citrate cycle stop functioning when citrate cycle intermediates are siphoned off for use by other pathways?

Heme degradation produces succinyl-CoA, which is sufficient to restore the downstream citrate cycle intermediates that may be lacking.

Citrate cycle intermediates are constantly imported into the mitochondria from the cytosol, so these metabolites are never in low abundance.

Anaplerotic reactions catalyze the formation of citrate cycle intermediates, which can then enter the citrate cycle and maintain a functioning pathway.

Oxaloacetate is the only citrate cycle intermediate that leaves the pathway, and it is replenished by pyruvate carboxylase.