Question

Answer only.

1. In the reaction of adding a phosphate group from ATP to glucose, the free energy from hydrolysis of ATP is need to drive the phosphorylation of glucose. The free energy released from the coupled reaction is -4.0 kcal/mol. Which of the following statement is not correct?

a) this reaction does not require any enzyme

b) this reaction does not occur at a detectable rate when the temperature is at -20˚

c) The equilibrium of the reaction is favored to form glucose-6-phosphate

d) At equilibrium the temperature of the reaction mixture is slightly higher than before the reaction occurs

2. Which of the following is NOT a role of the anaplerotic reaction of the intermediates of the citric acid cycle in cancer metabolism?

a) Generation of heme for the synthesis of cytochromes

b) Synthesis of amino acids for making proteins

c) Generation of citrate for fatty acid synthesis

d) Generation of glucose for glycolysis

3. After the hydrolysis of sucrose into individual monosaccharides, what is the change in sweetness?

a) Remain the same

b) Sweeter

c) Less sweet

d) As sweet as lactose

4. What is the free energy released or absorbed if the reaction has a K_eq = 1 at 25˚C

a) 32.3 kJ/mol

b) 0 J/mol

c) -1.44 kJ/mol

d) -2478 J/mol

5. Give that the gas constant is 8.315 Jmol^-1 K^-1, the equilibrium constant corresponding to a free energy of -26.5 kJ per mole at 25 ˚C is:

a) 2.369 x 10¹

b) 2.25 x 10³

c) 2.38 x 10^-5

d) 4.41 x 10⁴

6. why is B-D-glucopyranose the most abundant among all other forms such as the linear form and the furanose forms of glucose?

a) Putting 5 atoms in the furan ring is energetically favorable

b) B-configuration of the hydroxyl group of carbon atom 1 has the least steric hindrance

c) a-configuration of the hydroxyl group of carbon atom 1 has the least steric hindrance

d) Putting 6 atoms in the pyranose ring is energetically unfavorable

7. Which of the following can explain why a soup of 20 different free amino acids coming from the hydrolysis of a pure pyruvate kinase the hydrolysis of a pure pyruvate kinase solution is almost impossible to build up into a functional enzyme by linking these amino acids together by chance?

a) The enthalpy involved is too high to be gained form the environment

b) the temperature is not high enough to allow linking up

c) the decrease in entropy is too high

d) Building up of the enzyme requires a specific template to link up in a specific sequence

8. In the reaction of converting fructose -6- phosphate to fructose 1,6-bisphosphate, which of the following is NOT true?

a) the free energy change is highly negative

b) the concentration of ADP at the equilibrium of the reaction is very low

c) The extra phosphate group on fructose-6-bisphosphate comes from ATP

d) The entropy does not increase after the reaction

9. Which of the following best describes the type of reaction catalyzed by a dehydrogenase?

a) Deprotonation

b) Esterification

C) Hydrolysis

d) Oxidation-reduction

10. Which of the following is NOT a reason why carbon is the most important element in building up of biomolecules

a) Possession of various functional group

b) carbon can form bonds with hydrogen, oxygen and nitrogen atoms

c)carbon can link with other atoms with very strong triple bonds

d) carbon can form bonds with 1 to 4 atoms

11. During tumor growth, which of the following does not happen

a) Induction of hypoxia inducible factor

b) Increase in the levels of glycolytic enzymes

c) Increase in the consumption of glucose

d) Decrease in blood capillary appearing on the tumor

12. Why is the TCA cycle central pathway of metabolism of the cell?

a) It occurs in the center of the cell

b) Its intermediates are commonly used by other metabolic reaction

c) All other metabolic pathways depend upon it

d) None of the above

13. Which of the following signaling pathways does not involve a nucleotide?

a) G protein-coupled receptor

b) Second messenger generated by adenylyl cyclase

c) Receptor tyrosine kinase

d) None of the above

14. The synthesis of heme requires:

a) An amino acid and a product from the citric acid cycle

b) An amino acid and a product from the urea cycle

c) A fatty acid and a product from the urea cycle

d) None of the above

15. Which of the follow descriptions about K_d is correct for binding of O² to the T or R state of hemoglobin?

a) K_d of T state > K_d of R state

a) K_d of T state < K_d of R state

a) K_d of T state = K_d of R state

d) A and B could both be correct

16.Which of the following modifications is normally not present in proteins?

a) Polysaccharide conjugation

b) Lipid conjugation

c) Polyadenylation

d) Phosphorylation

Answer 1

c) The equilibrium of the reaction is favoured to form glucose-6-phosphate

This is a hydrolysis reaction. The glucose-6-phosphate is hydrolyzed to the glucose and phosphate. Biological hydrolysis reactions are almost always spontaneous (exergonic). The products of glucose and phosphate are at a lower energy level than the reactants. Since K_eq > 1, this is a spontaneous (exergonic) reaction starting with glucose-6-phosphate.

2. a) Generation of heme for the synthesis of cytochromes

Anaplerotic reactions are chemical reactions that form intermediates of a metabolic pathway. Examples of such are found in the citric acid cycle (TCA cycle).3a.

3a.Remains the same

When sucrose is hydrolyzed it forms a 1:1 mixture of glucose and fructose. Glucose is less sweet than sucrose and fructose is sweeter than sucrose.

9d. Oxidation-reduction reaction

Dehydrogenases are a subclass of the class of enzymes called “oxidoreductases.” Oxidoreductases, in general, catalyze oxidation and reduction reactions.

10c)carbon can link with other atoms with very strong triple bonds

11d. d) The decrease in blood capillary appearing on the tumour

Angiogenesis or increase in the blood capillaries is the primary function of tumor.

12b) Its intermediates are commonly used by other metabolic reaction

13c) Receptor tyrosine kinase

14c) A fatty acid and a product from the urea cycle

16b) Lipid conjugation