Question 1

Which of the following best describes the structure of an amino acid found in proteins?

Accepted Answer

A central carbon atom bonded to a hydrogen atom, an amino group, a carboxyl group, and a variable side chain (R-group).

Question 2

During protein synthesis, which type of chemical reaction links amino acids together to form a polypeptide chain?

Accepted Answer

Condensation (dehydration) reaction, which releases a water molecule.

Question 3

Which property of an amino acid is primarily determined by its side chain (R-group)?

Accepted Answer

Its chemical reactivity and whether it is hydrophobic or hydrophilic.

Question 4

A mutation changes a hydrophobic amino acid in the core of a protein to a hydrophilic one. What is the most likely consequence?

Accepted Answer

The protein may misfold or lose its function due to altered interactions.

Question 5

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

Accepted Answer

Storing genetic information for inheritance.

Question 6

What type of bond forms between the carboxyl group of one amino acid and the amino group of another during protein synthesis?

Accepted Answer

A peptide bond

Question 7

Which level of protein structure is defined by the sequence of amino acids in a polypeptide?

Accepted Answer

Primary structure

Question 8

Which of the following interactions is responsible for stabilizing the secondary structure of proteins?

Accepted Answer

Hydrogen bonds between backbone atoms

Question 9

A protein is unable to function after being exposed to high heat. What is the most likely explanation?

Accepted Answer

The protein has denatured, losing its specific three-dimensional structure.

Question 10

Which of the following statements about enzymes is correct?

Accepted Answer

Enzymes speed up chemical reactions by lowering the activation energy.

Question 11

Which of the following is a correct description of a nucleotide found in DNA?

Accepted Answer

A phosphate group, a deoxyribose sugar, and a nitrogenous base (A, T, C, or G)

Question 12

Which of the following best explains why DNA is a stable molecule for storing genetic information?

Accepted Answer

Its double helix structure and strong hydrogen bonding between complementary bases.

Question 13

What is the main structural difference between RNA and DNA?

Accepted Answer

RNA contains ribose and uracil; DNA contains deoxyribose and thymine.

Question 14

Which of the following correctly describes the directionality of nucleic acids?

Accepted Answer

Nucleic acids are synthesized in the 5' to 3' direction.

Question 15

Which of the following is true about complementary base pairing in DNA?

Accepted Answer

Adenine pairs with thymine, and guanine pairs with cytosine.

Question 16

Which of the following is a reason why RNA is thought to have preceded proteins in early evolution?

Accepted Answer

RNA can both store genetic information and catalyze chemical reactions.

Question 17

Which of the following is a correct statement about the secondary structure of RNA?

Accepted Answer

RNA can fold back on itself to form hairpin loops stabilized by hydrogen bonds.

Question 18

Which of the following is a correct description of a phosphodiester bond?

Accepted Answer

A bond between the phosphate group on the 5' carbon of one nucleotide and the hydroxyl group on the 3' carbon of another.

Question 19

Which of the following is a plausible consequence of a single base change in the DNA sequence coding for hemoglobin?

Accepted Answer

It can cause sickle cell anemia by altering the protein's structure and function.

Protein Structure and Function: Amino Acids and the Foundations of Proteins

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