Question 1

Which of the following best describes the change in free energy ($\Delta G$) for the hydrolysis of sucrose?

Accepted Answer

$\Delta G$ is positive, indicating a nonspontaneous reaction.

Question 2

A condensation reaction between glucose and fructose forms sucrose and water. What is the sign of $\Delta G$ for this reaction, and what does it indicate?

Accepted Answer

$\Delta G$ is negative, indicating the reaction is spontaneous.

Question 3

If the hydrolysis of ATP ($\Delta G = -30.5$ kJ/mol) is coupled to the hydrolysis of sucrose ($\Delta G = +23$ kJ/mol), what is the overall $\Delta G$ for the coupled reaction?

Accepted Answer

$\Delta G = -7.5$ kJ/mol

Question 4

Which level of protein structure is defined by the sequence of amino acids from the N-terminus to the C-terminus?

Accepted Answer

Primary structure

Question 5

What type of bond links amino acids together in a polypeptide chain?

Accepted Answer

Peptide bond

Question 6

Which of the following is a consequence of a mutation in the primary sequence of a tumor-suppressor protein?

Accepted Answer

The protein may become defective, leading to uncontrolled cell division.

Question 7

Which structural feature is stabilized by intramolecular hydrogen bonds between backbone atoms and can be arranged in parallel or antiparallel configurations?

Accepted Answer

Beta-sheet

Question 8

What is the main stabilizing force in the formation of an alpha-helix in proteins?

Accepted Answer

Hydrogen bonds between backbone atoms

Question 9

Which of the following statements about protein denaturation is correct?

Accepted Answer

Denaturation can be caused by exposure to high concentrations of urea.

Question 10

Prions are associated with which of the following diseases and mechanisms?

Accepted Answer

Creutzfeldt-Jakob disease; misfolded proteins that induce misfolding in normal proteins

Question 11

Which type of protein structure involves multiple polypeptide chains assembling into a functional unit?

Accepted Answer

Quaternary structure

Question 12

Disulfide bonds are important for stabilizing which levels of protein structure?

Accepted Answer

Tertiary and quaternary

Question 13

Which of the following best describes the role of enzymes in biological reactions?

Accepted Answer

Enzymes decrease the activation energy, speeding up reactions.

Question 14

Competitive inhibitors affect enzyme activity by:

Accepted Answer

Binding to the active site and requiring higher substrate concentration to reach maximum rate.

Question 15

Allosteric regulation of enzymes involves:

Accepted Answer

Binding of molecules to sites other than the active site, changing enzyme activity.

Question 16

Cooperativity in proteins such as hemoglobin results in:

Accepted Answer

Increased affinity for oxygen after each oxygen binds.

Question 17

Phosphorylation of proteins is typically carried out by which type of enzyme?

Accepted Answer

Kinase

Question 18

Which of the following statements about protein domains is correct?

Accepted Answer

Domains are regions of a protein with distinct structure and function.

Question 19

Which of the following is a real-world example of a protein whose function depends on quaternary structure?

Accepted Answer

Hemoglobin

Question 20

A mutation causes a protein to misfold and aggregate in neurons, leading to neurodegeneration. This is most likely due to:

Accepted Answer

Formation of prions

Reaction Energetics and Protein Structure in General Biology

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