Question 1

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

Accepted Answer

One strand runs 5' to 3' and the other runs 3' to 5'.

Question 2

During DNA replication, why is the lagging strand synthesized in short fragments rather than continuously?

Accepted Answer

DNA polymerase can only add nucleotides to the 3' end, and the lagging strand is oriented 5' to 3' away from the replication fork.

Question 3

Which enzyme is responsible for removing RNA primers and replacing them with DNA nucleotides during DNA replication?

Accepted Answer

DNA polymerase I

Question 4

A mutation changes a DNA codon from $$	ext{GAA} to$$ $$	ext{GAG}$$, but both code for glutamic acid. What type of mutation is this?

Accepted Answer

Silent mutation

Question 5

Which of the following best explains why the 5' end RNA primer on the leading strand cannot be replaced with DNA nucleotides?

Accepted Answer

DNA polymerase requires a free 3' OH group to add nucleotides, which is absent at the very end.

Question 6

Which of the following modifications to chromatin structure is most likely to increase gene expression?

Accepted Answer

Histone acetylation

Question 7

A scientist discovers a segment of DNA that is tightly packed and transcriptionally inactive. This region is most likely:

Accepted Answer

Heterochromatin

Question 8

Which of the following best describes the function of tRNA during translation?

Accepted Answer

It carries amino acids to the ribosome and matches them to the mRNA codon via its anticodon.

Question 9

Which of the following is a function of the 5' cap added to eukaryotic mRNA?

Accepted Answer

It protects mRNA from degradation and assists in ribosome binding.

Question 10

Which of the following best describes the role of a spliceosome?

Accepted Answer

It removes introns and joins exons in the primary RNA transcript.

Question 11

A mutation causes a premature stop codon in the middle of a gene. What type of mutation is this, and what is its likely effect?

Accepted Answer

Nonsense mutation; likely results in a nonfunctional protein.

Question 12

Which of the following best describes the difference between repressible and inducible operons?

Accepted Answer

Repressible operons are usually on and can be turned off; inducible operons are usually off and can be turned on.

Question 13

Which of the following is a direct result of alternative RNA splicing?

Accepted Answer

A single gene can code for multiple proteins.

Question 14

Which of the following best describes the function of microRNAs (miRNAs) in gene regulation?

Accepted Answer

They bind to complementary mRNA sequences and can block translation or lead to mRNA degradation.

Question 15

A patient has a genetic disorder caused by a frameshift mutation. Which of the following best explains how this mutation affects the protein?

Accepted Answer

It alters the reading frame, changing every amino acid downstream of the mutation.

Question 16

Which of the following best describes the role of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments on the lagging strand by forming phosphodiester bonds.

Question 17

Which of the following is a function of a proteasome in the cell?

Accepted Answer

It degrades unneeded or damaged proteins into peptides.

Question 18

Which of the following best explains the concept of epigenetic inheritance?

Accepted Answer

Inheritance of traits transmitted by mechanisms not directly involving changes in the DNA sequence.

Question 19

Which of the following is true about the relationship between DNA, mRNA, and protein synthesis?

Accepted Answer

The sequence of nucleotides in DNA determines the sequence of amino acids in a protein via an mRNA intermediate.

Molecular Basis of Inheritance and Regulation of Gene Expression: Study Guide

Study Guide - Practice Questions