Question 1

Which of the following statements best describes the difference between a polypeptide and a protein?

Accepted Answer

A polypeptide is a single unbranched polymer of amino acids, while a protein is a functional molecule made of one or more polypeptides.

Question 2

Which of the following amino acids is the only one that does NOT have separate L and D isomers?

Accepted Answer

Glycine

Question 3

During the formation of a peptide bond between two amino acids, which type of reaction occurs and what is released?

Accepted Answer

Dehydration (condensation) reaction; water is released

Question 4

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

Accepted Answer

Hydrogen bonds between NH and CO groups of the peptide backbone

Question 5

A mutation changes a single amino acid in the primary structure of a protein. Which levels of protein structure could potentially be affected?

Accepted Answer

Primary, secondary, tertiary, and quaternary structures

Question 6

Which of the following best explains why proline is referred to as a 'helix breaker' in protein secondary structure?

Accepted Answer

It lacks the hydrogen atom needed for hydrogen bonding.

Question 7

Hemoglobin is an example of a protein with which type of structure?

Accepted Answer

Quaternary structure

Question 8

Which of the following interactions is NOT involved in stabilizing the tertiary structure of proteins?

Accepted Answer

Phosphodiester bonds

Question 9

Which component of DNA and RNA is responsible for the 'acidic' property of nucleic acids?

Accepted Answer

The phosphate group

Question 10

Which of the following best describes the directionality of nucleic acid synthesis?

Accepted Answer

Nucleotides are added to the 3' end, and sequences are written 5' to 3'

Question 11

Which of the following statements about complementary base pairing in nucleic acids is correct?

Accepted Answer

Adenine forms two hydrogen bonds with thymine (or uracil), and guanine forms three hydrogen bonds with cytosine.

Question 12

A researcher isolates a fibrous protein from silk. Which secondary structure is most likely predominant in this protein?

Accepted Answer

β sheet

Question 13

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

Accepted Answer

Hemoglobin

Question 14

Which of the following best describes the bond formed between two nucleotides in a nucleic acid polymer?

Accepted Answer

Phosphodiester bond

Question 15

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

Accepted Answer

The two strands are antiparallel and held together by hydrogen bonds between complementary bases.

Question 16

Which of the following amino acids contains a sulfur atom that can form disulfide bonds, contributing to protein tertiary structure?

Accepted Answer

Cysteine

Question 17

A mutation causes a change in the R group of an amino acid from hydrophobic to hydrophilic. Which level(s) of protein structure could this most directly affect?

Accepted Answer

Secondary and tertiary structures

Question 18

Which of the following best explains why DNA is more stable than RNA under alkaline conditions?

Accepted Answer

DNA lacks a 2' hydroxyl group on the sugar, making it less susceptible to hydrolysis.

Question 19

Which of the following is a function of storage proteins in cells?

Accepted Answer

Serving as reservoirs of amino acids

Question 20

Which of the following best describes the relationship between the sequence of nucleotides in mRNA and the primary structure of a protein?

Accepted Answer

The sequence of nucleotides in mRNA determines the order of amino acids in the protein.

Macromolecules of the Cell: Structure, Properties, and Functions

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