Question 1

Which of the following best describes the primary structure of a peptide?

Accepted Answer

The sequence of amino acids linked by peptide bonds

Question 2

A peptide has the sequence Cys-Ala-Gln-Gly-Ser-Arg. Which amino acid is at the C-terminus?

Accepted Answer

Arg

Question 3

Which of the following interactions is most responsible for the favorable entropic change during protein folding?

Accepted Answer

The decrease in ordered water molecules as hydrophobic amino acids pack together

Question 4

Consider a polypeptide with the following sequence: Ala-Lys-Glu at pH 7.0. Which amino acid side chain is most likely to be positively charged?

Accepted Answer

Lys

Question 5

A helical segment of a protein is embedded in a membrane. Which region of the helix is most likely to be hydrophobic?

Accepted Answer

The region embedded in the membrane

Question 6

Which of the following best explains why hemoglobin exhibits cooperative binding of oxygen?

Accepted Answer

Oxygen binding causes a conformational change that increases affinity at other sites

Question 7

In the oxygen dissociation curve for hemoglobin, which condition would shift the curve furthest to the left?

Accepted Answer

Decreased temperature

Question 8

A mutation in hemoglobin replaces Lys-82 with an asparagine residue. What is the most likely effect on hemoglobin function?

Accepted Answer

Decreased affinity for 2,3-BPG

Question 9

Which enzyme class typically has a pKa near physiological pH and is involved in proton transfer during catalysis?

Accepted Answer

Acid-base catalyst

Question 10

A metalloenzyme contains two histidine residues and coordinates a Cu$$^{2+}$$ ion. When the ion is present in the active site, the enzyme is a(n):

Accepted Answer

Holoenzyme

Question 11

Which of the following is true regarding the effect of an enzyme on the activation energy ($$E_a) of a $$reaction?

Accepted Answer

The enzyme decreases the activation energy

Question 12

Given the reaction coordinate diagram for two enzymes, Enzyme 1 and Enzyme 2, which statement is correct if Enzyme 1 has a lower activation energy than Enzyme 2?

Accepted Answer

Enzyme 1 would catalyze the reaction faster than Enzyme 2

Question 13

In a proposed mechanism, AA11 donates a proton to the substrate to form the product. What type of catalysis is this?

Accepted Answer

Acid catalysis

Question 14

Which of the following best describes the role of 2,3-BPG in hemoglobin function?

Accepted Answer

It stabilizes the T (tense) state and promotes oxygen release

Question 15

Which of the following is a consequence of the hydrophobic effect in protein folding?

Accepted Answer

Hydrophobic amino acids pack together in the protein interior

Question 16

Which of the following statements about the secondary structure of proteins is correct?

Accepted Answer

It includes alpha helices and beta sheets stabilized by hydrogen bonds

Question 17

A protein is denatured by heating. Which level of structure is most directly disrupted?

Accepted Answer

Tertiary structure

Question 18

Which of the following amino acids is most likely to be found on the surface of a soluble protein?

Accepted Answer

Glutamate

Question 19

Which of the following is true about the effect of pH on the charge of amino acid side chains?

Accepted Answer

At low pH, basic side chains are positively charged

Question 20

Which of the following is a correct statement about enzyme specificity?

Accepted Answer

Enzymes bind substrates with high specificity due to their active site structure

Biochemistry Exam Practice: Protein Structure, Function, and Enzyme Catalysis

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