Question 1

Which of the following statements best describes the role of proteins in cellular metabolism?

Accepted Answer

Proteins are the main chemicals responsible for catalyzing nearly all chemical reactions in cells, including metabolism.

Question 2

A peptide bond is formed between which two groups of amino acids?

Accepted Answer

The carboxyl group of one amino acid and the amino group of another amino acid.

Question 3

Which of the following amino acids is classified as acidic based on its side chain?

Accepted Answer

Aspartic acid

Question 4

Enzymes require certain non-protein molecules to function properly. These molecules are called:

Accepted Answer

Cofactors

Question 5

Which process is described by the following equation: $$\mathrm{Glucose} + 2\ \mathrm{NAD}^+ + 2\ \mathrm{ADP} + 2\ \mathrm{P_i} \rightarrow 2\ \mathrm{Pyruvate} + 2\ \mathrm{NADH} + 2\ \mathrm{ATP} + 2\ \mathrm{H_2O}$$ ?

Accepted Answer

Glycolysis

Question 6

A mutation changes the DNA sequence coding for the active site of an enzyme. What is the most likely consequence?

Accepted Answer

The enzyme may lose its ability to bind its substrate and catalyze the reaction.

Question 7

Which of the following best explains why metabolic pathways require multiple enzymes?

Accepted Answer

Each enzyme catalyzes a specific chemical change, and complex molecules require stepwise modifications.

Question 8

Which amino acid would most likely be found in the hydrophobic core of a globular protein?

Accepted Answer

Valine

Question 9

What is the main function of phosphorylation in regulating enzyme activity?

Accepted Answer

It attaches a phosphate group to the enzyme, which can turn the enzyme on or off.

Question 10

Which of the following statements about amino acids is correct?

Accepted Answer

Amino acids differ in their R groups, which determine their chemical properties.

Question 11

A scientist discovers a new protein that is only active at a pH of 2. Which amino acid is most likely to be important in its active site?

Accepted Answer

Aspartic acid

Question 12

Which of the following is a product of an enzyme-catalyzed reaction?

Accepted Answer

Product

Question 13

During glycolysis, which molecule is directly used to transfer energy to produce ATP?

Accepted Answer

Phosphoenolpyruvate (PEP)

Question 14

Which of the following best describes the difference between hydrophobic and hydrophilic amino acids?

Accepted Answer

Hydrophobic amino acids have side chains that avoid water, while hydrophilic amino acids have side chains that interact with water.

Question 15

Which of the following is NOT a function of proteins in cells?

Accepted Answer

Storing genetic information

Question 16

A metabolic intermediate in glycolysis, 3-phosphoglycerate, can be converted into which type of biomolecule?

Accepted Answer

Amino acids

Question 17

Which of the following best explains why humans must obtain some amino acids from their diet?

Accepted Answer

Humans lack the metabolic pathways to synthesize all 20 amino acids.

Question 18

Which of the following is true about the structure of enzymes?

Accepted Answer

Enzymes have a specific 3D shape that allows them to bind substrates and catalyze reactions.

Question 19

Which amino acid is most likely to be found at the active site of an enzyme that catalyzes a reaction requiring a basic environment?

Accepted Answer

Arginine

Question 20

In a metabolic pathway, what is the role of the enzyme labeled 'Enzyme 2' in the following sequence? $$\mathrm{Molecule\ A} \xrightarrow{\mathrm{Enzyme\ 1}} \mathrm{Molecule\ B} \xrightarrow{\mathrm{Enzyme\ 2}} \mathrm{Molecule\ C}$$

Accepted Answer

Enzyme 2 converts Molecule B into Molecule C by catalyzing a specific chemical reaction.

Proteins, Amino Acids, and Metabolism: Foundations of Cellular and Molecular Biology

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