1) A mutation occurs in a gene which causes an arginine to be replaced by a phen

Question

1) A mutation occurs in a gene which causes an arginine to be replaced by a phenylalanine in the corresponding protein. What type of change has taken place in the mutant protein? A) A nonpolar amino acid has been replaced with a polar, uncharged amino acid B) A basic amino acid has been replaced by a nonpolar amino acid C) A nonpolar amino acid has been replaced by a basic amino acid. D) An acidic amino acid has been replaced by a basic amino acid E) A polar, uncharged amino acid has been replaced by a basic amino acid 2) Considering how an enzyme behaves inside a cell, a small Michaelis constant (Km) indicates that the enzyme activity will NOT typically vary with fluctuations in [SJ A) True. B) False 3) True or False?: Fats contain more extractable energy per gram because they are more reduced compar carbohydrates and proteins A) True B) False because fats are NOT more reduced compared to carbohydrates and proteins. C) False because fats do NOT contain more extractable energy per gram compared to carbohydrates proteins. 4) Which of the following statements describes NAD+? A) NAD+ is oxidized by the action of hydrogenases. B) In the absence of NADt, glycolysis can still function. C) NAD+ has more chemical energy than NADH. D) NAD+ can donate electrons for use in oxidative phosphorylation. E) NADH is the reduced form of NAD+. 5) Which of the following functional groups would NOT be charged in an aqueous solution? A) carboxyl B) amino C) phosphate D) hydroxyl E) All of the above functional groups would be charged in an aqucous solution

Explanation / Answer

1. Arginine is a basic polar amino acid and phenylalanine is nonpolar. Hence in mutant protein a basic amino acd is replaced by nonpolar amino acid. Therefore, your answer is (B).

2. A small Michaelis Menten constant means that the enzyme has high affinity for its substrate and enzyme activity will not be much dependent on substrate concentration. Therefore, your answer is TRUE.

3. Fats contain more extractable energy per gram because the amount of oxidation that takes place as fats are converted to carbon dioxide and water. Therefore your answer is TRUE.

4. In metabolic reactions NAD+ gains electrons and is converted to NADH, hence NADH is reduced form of NAD+. Therefore your answer is (E).

5. All the given functional groups i.e. carboxyl group, amino group, phosphate group and hydroxyl group either protonate or deprotonate in an aqueous solution, hence they all will be charged to some degree in aqueous solutions. Therefore, your answer is (E).

6. The CFTR protein only transports chlorideand thiocyanate ions across epithelial cell membranes. Therefore, your answer is FALSE.

7. The net end products of glycolysis are two Pyruvate, two NADH, and two ATP. Therefore, your answer is (E).

8. Citric acid cycle takes place inside mitochondrial matrix while Oxidative phosphorylation takes place in the inner mitochondrial membrane, and glycolysis takes place outside mitochodria in the cytosol. Therefore, your answer is (A).

9. Chlorophyll only absorbs light in green range of visible light spectrum and reflects all other wave-lengths. Therefore, your answer is FALSE.

10. In aerobic respiration oxygen is used to oxidize glucose into CO2, also in this process oxygen itself gets reduced to H2O. Therefore, your answer is (D).

11. The electrons passed along the electron transport system from photosystem II is used for all the following purposes- to establish and maintain a proton gradient, it excites electrons in the reaction center of photosystem I, and used to phosphorylate NAD+ and NADPH. Therefore, your answer is (E).

12. Red blood cells would lyse fastest in hypertonic sucrose solution as water from inside the cell will move out of the cell under osmotic pressure created due to concentration gradient of sucrose. Therefore, your answer is (B).

Thanks!

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