Question 1

Which of the following correctly describes the difference between a nucleoside and a nucleotide?

Accepted Answer

A nucleoside consists of a base and a sugar, while a nucleotide consists of a base, sugar, and phosphate.

Question 2

Which base is found in RNA but not in DNA?

Accepted Answer

Uracil

Question 3

What stabilizing force is most responsible for the stability of the DNA double helix?

Accepted Answer

Base stacking interactions driven by entropic forces

Question 4

Which statement best explains why AT-rich DNA denatures more easily than GC-rich DNA?

Accepted Answer

AT pairs have fewer hydrogen bonds and lower base stacking energy.

Question 5

What is the correct order of events in the central dogma of molecular biology?

Accepted Answer

Replication → Transcription → Translation

Question 6

Which of the following is a purine base found in nucleic acids?

Accepted Answer

Adenine

Question 7

What is the main difference between ribose and deoxyribose sugars in nucleic acids?

Accepted Answer

Ribose has a 2'-OH group, while deoxyribose lacks a 2'-OH group.

Question 8

Which of the following equations represents the number of hydrogen bonds between guanine and cytosine in DNA?

Accepted Answer

$$3$$

Question 9

A mutation in the beta globin gene changes the codon GAG to GTG. What is the resulting amino acid change?

Accepted Answer

Glutamic acid to valine

Question 10

Which of the following best describes the arrangement of DNA strands in the double helix?

Accepted Answer

The strands are antiparallel and run in opposite directions.

Question 11

Which of the following molecules contains adenosine and is involved in oxidation-reduction reactions?

Accepted Answer

NAD

Question 12

What is the function of messenger RNA (mRNA) in the cell?

Accepted Answer

Encodes for polypeptide sequences

Question 13

Which of the following best describes the process of DNA denaturation?

Accepted Answer

Unfolding of the double helix due to thermal or chemical stress

Question 14

Which of the following is a practical application of the polymerase chain reaction (PCR)?

Accepted Answer

Amplifying specific DNA sequences for genetic analysis

Question 15

Which of the following statements about genomic analysis is correct?

Accepted Answer

Genomic analysis can reveal both coding and noncoding regions, as well as genetic variations linked to disease.

Question 16

Which of the following equations represents the directionality of DNA synthesis?

Accepted Answer

$$5' \rightarrow 3'$$

Question 17

Which of the following is a reason why water molecules stabilize the DNA double helix?

Accepted Answer

Water molecules cluster in the major groove and hold water in the minor groove, supporting base stacking interactions.

Question 18

Which of the following best describes the role of transfer RNA (tRNA) in translation?

Accepted Answer

tRNA carries amino acids to the ribosome and binds to its complement in the mRNA template.

Question 19

Which of the following is a consequence of a single-nucleotide polymorphism (SNP) in the human genome?

Accepted Answer

SNPs can be linked to increased risk for diseases such as Type 2 Diabetes or Crohn's disease.

Nucleic Acid Structure and Function: Study Notes for Biochemistry

Study Guide - Practice Questions