Question 1

Which of the following statements best describes the role of water in biochemical systems?

Accepted Answer

Water is a reactant in hydrolysis reactions and helps stabilize macromolecular structures through hydrogen bonding.

Question 2

A buffer system is used in a biochemical experiment to maintain pH. If the buffer consists of acetic acid ($$CH_3COOH) $$and its conjugate base ($$CH_3COO^-$$), which equation best describes the relationship between pH, pKa, and the concentrations of acid and base?

Accepted Answer

$$pH = pK_a + \log \left( \frac{[CH_3COO^-]}{[CH_3COOH]} \right)$$

Question 3

Which amino acid is most likely to be found at the active site of an enzyme that catalyzes acid-base reactions?

Accepted Answer

Histidine

Question 4

During protein purification, which technique would be most effective for separating proteins based on their size?

Accepted Answer

Gel filtration chromatography

Question 5

A protein is found to have a high content of $$eta-$$sheets. Which of the following statements about $$eta-$$sheets is correct?

Accepted Answer

$$\beta-$$sheets are stabilized by hydrogen bonds between backbone amide and carbonyl groups.

Question 6

Hemoglobin and myoglobin both bind oxygen. Which statement best explains why hemoglobin exhibits cooperative binding while myoglobin does not?

Accepted Answer

Hemoglobin has multiple subunits that interact, allowing for allosteric regulation.

Question 7

Which of the following best describes the Michaelis-Menten equation for enzyme kinetics?

Accepted Answer

$$v = \frac{V_{max} \cdot [S]}{K_m + [S]}$$

Question 8

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Increasing $$K_m$$ without affecting $$V_{max}$$

Question 9

Which of the following is a correct statement about the structure of DNA?

Accepted Answer

DNA consists of two antiparallel strands held together by hydrogen bonds between complementary bases.

Question 10

Which process is responsible for the movement of ions across a membrane against their concentration gradient?

Accepted Answer

Active transport

Question 11

Which of the following statements about membrane fluidity is correct?

Accepted Answer

Membrane fluidity increases as the proportion of unsaturated fatty acids increases.

Question 12

Which of the following best describes the function of G proteins in signal transduction?

Accepted Answer

G proteins act as molecular switches, cycling between active (GTP-bound) and inactive (GDP-bound) states.

Question 13

A patient is diagnosed with sickle cell anemia. Which change in the hemoglobin protein is responsible for this disease?

Accepted Answer

A substitution of glutamic acid with valine at position 6 of the $$eta-$$chain.

Question 14

Which of the following is a correct statement about the phosphoinositide pathway?

Accepted Answer

It involves the hydrolysis of $$PIP_2 to $$generate $$IP_3$$ and diacylglycerol (DAG), which act as second messengers.

Question 15

Which of the following best explains why enzymes are highly specific for their substrates?

Accepted Answer

Enzymes use the induced fit model, where the active site changes shape to accommodate the substrate.

Question 16

Which of the following is true regarding the thermodynamics of biochemical reactions?

Accepted Answer

A reaction with $$\Delta G \u003c 0 is $$spontaneous under standard conditions.

Question 17

Which of the following statements about protein folding is correct?

Accepted Answer

Protein folding is driven by the hydrophobic effect and the formation of secondary and tertiary structures.

Question 18

Which of the following is a correct statement about the function of lysozyme?

Accepted Answer

Lysozyme catalyzes the hydrolysis of glycosidic bonds in bacterial cell walls.

Question 19

Which of the following best describes the role of ATP in cellular metabolism?

Accepted Answer

ATP serves as the primary energy currency, coupling exergonic and endergonic reactions.

BCH4053.0001: Biochemistry I Syllabus and Course Structure

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