Question 1

Which of the following best describes the process by which a peptide bond is formed between two amino acids?

Accepted Answer

A condensation reaction that releases a molecule of water ($$H_2O)$$

Question 2

A mutation causes a hydrophobic amino acid in a protein to be replaced by a hydrophilic one. Which of the following is the most likely consequence for the protein’s structure?

Accepted Answer

The protein may misfold due to altered interactions with water and other side chains.

Question 3

Which of the following amino acids contains a sulfur atom in its side chain and can form disulfide bridges?

Accepted Answer

Cysteine

Question 4

What is the correct order of protein structural levels from the sequence of amino acids to the assembly of multiple polypeptide chains?

Accepted Answer

Primary, secondary, tertiary, quaternary

Question 5

Which of the following statements about the structure of amino acids is correct?

Accepted Answer

All amino acids have an amino group ($$NH_2$$), a carboxyl group ($$COOH$$), a hydrogen atom, and a unique R group attached to the alpha carbon.

Question 6

Which of the following amino acids is classified as nonpolar and hydrophobic?

Accepted Answer

Leucine

Question 7

A patient with sickle cell anemia has a mutation in the hemoglobin gene that replaces glutamic acid with valine. What is the most significant chemical difference between these two amino acids?

Accepted Answer

Glutamic acid is acidic and hydrophilic, while valine is nonpolar and hydrophobic.

Question 8

Which of the following best explains why proteins can spontaneously refold after being unfolded?

Accepted Answer

The chemical and physical interactions of the amino acid side chains drive the correct folding.

Question 9

Which of the following is true about the directionality of polypeptide synthesis?

Accepted Answer

Polypeptides are synthesized from the amino (N-) terminus to the carboxyl (C-) terminus.

Question 10

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

Accepted Answer

Hydrogen bonds

Question 11

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

Accepted Answer

DNA contains deoxyribose and thymine, while RNA contains ribose and uracil.

Question 12

During DNA replication, which strand is synthesized continuously in the 5'-3' direction?

Accepted Answer

Leading strand

Question 13

Which of the following base pairs are correctly matched according to the rules of DNA base pairing?

Accepted Answer

Adenine ($$A) $$pairs with Thymine ($$T)$$

Question 14

Which of the following statements about the flow of genetic information in a cell is correct?

Accepted Answer

DNA is transcribed to RNA, which is then translated to protein.

Question 15

Which of the following is a function of the ribosome in protein synthesis?

Accepted Answer

It reads the mRNA sequence and assembles the corresponding polypeptide chain.

Question 16

Which of the following is true about the antiparallel orientation of DNA strands?

Accepted Answer

One strand runs 5' to 3', while the complementary strand runs 3' to 5'.

Question 17

Which of the following amino acids is basic and positively charged at physiological pH?

Accepted Answer

Lysine

Question 18

A protein is found to have two independently folded domains. Which level of protein structure does this observation most directly relate to?

Accepted Answer

Tertiary structure

Question 19

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

Accepted Answer

A covalent bond formed between the carboxyl group of one amino acid and the amino group of another

Question 20

Which of the following best explains why genetic diseases can result in toxic effects due to misfolded proteins?

Accepted Answer

Misfolded proteins can aggregate and disrupt cellular function.

Lec 4: Proteins, Nucleic Acids, and Their Building Blocks: Structure and Function

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