GLUCONEOGENESIS, THE PENTOSE PHOSPHATE PATHWAY, and GLYCOGEN METABOLISM

1. Which amino acids can be used in gluconeogenesis?

A. Leucine

B. Lysine

C. Glycine

D. Valine

E. Serine

2. Where does gluconeogenesis occur?

A. Liver

B. Spleen

C. Small intestine

D. Kidney

E. Stomach

3. What is the only thing you cannot make glucose from?

A. Amino acids

B. Fatty acids

C. Glycerol

D. Lactic acid

E. Pyruvic acid

4. What are the substrates for gluconeogenesis in times of prolonged fasting?

A. Lactate

B. Pyruvate

C. Glycerol

D. Alpha-ketoacids

E. Glycogen

5. Name the unique enzymes of gluconeogenesis:

A. Pyruvate kinase

B. Pyruvate dehydrogenase

C. Pyruvate carboxylase

D. Glucokinase

E. Hexokinase

6. Name the unique enzymes of gluconeogenesis:

A. Glucose 6-phosphatase

B. Phosphoglucose isomerase

C. Phosphoglucomutase

D. Fructose 1,6-bisphosphatase

E. Phosphoglycerate mutase

7. What is the role of pyruvate carboxylase?

A. Pyruvate → lactate

B. Pyruvate → acetyl-CoA

C. Pyruvate → alanine

D. Pyruvate → oxaloacetate

8. Where does pyruvate carboxylase work?

A. In cytosol

B. In mitochondrial matrix

C. In endoplasmic reticulum

D. In nucleus

E. In the blood

9. What is the coenzyme used by pyruvate carboxylase?

A. Biotin

B. Pyridoxal phosphate

C. Thiamine diphosphate

D. Tetrahydrofolate

E. Ascorbic acid

10. What is the role of PEP carboxykinase?

A. PEP → pyruvate

B. PEP → oxaloacetate

C. 2-phosphoglycerate → PEP

D. Pyruvate → lactate

E. Pyruvate → oxaloacetate

11. What is used to decarboxylate cytosolic oxaloacetate?

A. Carbon dioxide

B. Water

C. GTP

D. ATP

E. NADH

12. What is the expensive reaction in gluconeogenesis that generates a very high energy intermediate?

A. Pyruvate carboxylase

B. PEP carboxykinase

C. Enolase

D. Glyceraldehyde 3-phosphate dehydrogenase

E. Lactate dehydrogenase

13. What is the hydrolytic enzyme that overcomes the second irreversible step in gluconeogenesis?

A. Pyruvate dehydrogenase

B. Pyruvate carboxylase

C. PEP carboxykinase

D. Fructose 1,6-bisphosphatase

E. Glucose 6-phosphatase

14. What overcomes the last irreversible step in gluconeogenesis?

A. Pyruvate dehydrogenase

B. Pyruvate carboxylase

C. PEP carboxykinase

D. Fructose 1,6-bisphosphatase

E. Glucose 6-phosphatase

15. What is the energy requirement for gluconeogenesis (starting with two pyruvate molecules)?

A. 2 ATP

B. 4 ATP

C. 6 ATP

D. 8 ATP

E. 10 ATP

16. Which one of the following statements concerning GNG is correct:

A. It occurs in muscle

B. It uses carbon skeletons provided by degradation of fatty acids

C. It occurs exclusively in cytosol

D. It is important in maintaining blood glucose during the normal overnight fast

E. It involves lactate as intermediate

17. Which of the following reactions is unique to GNG?

A. Lactate → pyruvate

B. Oxaloacetate → PEP

C. PEP → pyruvate

D. Glucose 6-phosphate → fructose 6-phosphate

E. Fructose 6-phosphate → fructose 1,6-bisphosphate

18. In the glycogen synthase reaction, the precursor to glycogen is:

A. glucose 6-phosphate

B. UTP-glucose

C. UDP-glucose

D. GDP-glucose

E. Glucose 1-phosphate

19. Glycogen has

A. α-1,4 linkages

B. α-1,6 linkages

C. α-1,4 and α-1,6 linkages

D. α-1,4 and β-1,6 linkages

20. What are the two glycogen storage sites in the body?

A. Brain

B. Spleen

C. Small intestine

D. Kidney

E. Liver

F. Skeletal muscles

21. What are the primary products of the pentose phosphate pathway?

A. Glucose 6-phosphate

B. Ribose 5-phosphate

C. NADPH·H⁺

D. Glyceraldehyde 3-phosphate

E. 6-phosphogluconate

22. Where is the pentose phosphate pathway active in your body?

A. Liver

B. Kidney

C. Adipose tissue

D. Erythrocytes

E. Brain

23. Name the key enzymes of the pentose phosphate pathway:

A. Glucose 6-phosphatase

B. Glucose 6-phosphate dehydrogenase

C. Lactonase

D. 6-phosphogluconate dehydrogenase

E. Glucokinase

24. What can be synthesized with the use of NADPH?

A. Glucose

B. Fatty acids

C. Amino acids

D. Cholesterol

E. Steroid hormones

25. Which vitamin is synthesized with the use of NADPH?

A. A

B. E

C. D

D. K

E. H

26. Indicate which statements about the pentose phosphate pathway are true:

A. It generates NADH for reductive biosynthesis

B. The reactions occur in the cytosol

C. It is more active in myocytes than in adipocytes

D. It interconverts trioses, tetroses, pentoses, hexoses, and heptoses

E. Through this pathway, excess ribose 5-phosphate can be converted into glycolytic intermediates

27. Indicate which statements about the pentose phosphate pathway are false:

A. It generates NADPH for reductive biosynthesis

B. The reactions occur in the cytosol

C. The reactions occur in the mitochondria

D. It is more active in myocytes than in adipocytes

E. It interconverts trioses, tetroses, pentoses, hexoses, and heptoses

28. Indicate which statements about gluconeogenesis are true:

A. It occurs completely in the mitochondrial matrix

B. Pyruvate carboxylase, catalyzing an anaplerotic reaction, is the first regulatory enzyme in the pathway

C. Precursors of hexoses include lactate, pyruvate, glycerol, and alanine

D. The three bypass reactions have ΔG values near zero, whereas other gluconeogenic reactions have large, negative ΔG values

E. Some reactions occur in the mitochondrial matrix and some in the cytoplasm

29. Name the initial product of phosphorolysis of glycogen by phosphorylase:

A. Glucose 1-phosphate

B. Glucose

C. Glucose 6-phosphate

D. Fructose 1-phosphate

E. Fructose

30. Indicate the class of glucose 6-phosphatase:

A. Oxidoreductase

B. Transferase

C. Hydrolase

D. Lyase

E. Isomerase

F. Ligase