Question 1

Which of the following best describes the 'central dogma' of molecular biology?

Accepted Answer

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

Question 2

A DNA sequence reads 5'-ATG GAA TGA-3'. What is the corresponding mRNA sequence after transcription (assume no introns)?

Accepted Answer

5'-AUG GAA UGA-3'

Question 3

During eukaryotic transcription, which of the following is NOT a function of the spliceosome?

Accepted Answer

Addition of a 5' cap to mRNA

Question 4

Which enzyme is responsible for attaching the correct amino acid to its corresponding tRNA?

Accepted Answer

Aminoacyl-tRNA synthetase

Question 5

In the lac operon, what is the effect of lactose on the lac repressor?

Accepted Answer

Lactose binds to the repressor, causing it to release from the operator.

Question 6

Which of the following best explains why transcription and translation can occur simultaneously in prokaryotes but not in eukaryotes?

Accepted Answer

Prokaryotes lack a nuclear envelope, so ribosomes can access mRNA as it is being transcribed.

Question 7

A mutation changes the codon 5'-UUU-3' to 5'-UUC-3'. Both code for phenylalanine. What type of mutation is this?

Accepted Answer

Silent mutation

Question 8

Which of the following is a function of histone acetyltransferases (HATs) in chromatin remodeling?

Accepted Answer

They add acetyl groups to histones, leading to a more open chromatin structure.

Question 9

Which of the following statements about operons is correct?

Accepted Answer

An operon is a group of genes under the control of a single promoter and operator.

Question 10

A cell is exposed to a signal that activates a transcription factor. Which of the following sequences of events is most likely to occur?

Accepted Answer

Signal → transcription factor activation → nuclear translocation → binding to enhancer → increased transcription

Question 11

Which of the following is an example of post-translational modification?

Accepted Answer

Phosphorylation of a protein after translation

Question 12

Which of the following best describes a regulon?

Accepted Answer

A set of genes or operons controlled by a common regulatory protein, even if they are not adjacent.

Question 13

If a eukaryotic gene is constitutively expressed, what does this mean?

Accepted Answer

The gene is transcribed at a constant rate regardless of environmental conditions.

Question 14

Which of the following is a key difference between the lac repressor and the trp repressor?

Accepted Answer

The lac repressor is inactivated by its substrate (lactose), while the trp repressor is activated by its product (tryptophan).

Question 15

Which of the following best describes alternative splicing?

Accepted Answer

The process by which different combinations of exons are joined to produce multiple mRNAs from a single gene.

Question 16

A mutation in a gene results in a premature stop codon. What is the most likely effect on the protein product?

Accepted Answer

The protein will be truncated and likely nonfunctional.

Question 17

Which of the following mechanisms is involved in RNA interference (RNAi)?

Accepted Answer

Small RNA molecules bind to mRNA, leading to its degradation or blocking translation.

Question 18

Which of the following best explains the difference between genetics and epigenetics?

Accepted Answer

Genetics involves changes in DNA sequence, while epigenetics involves changes in gene expression without altering the DNA sequence.

Question 19

If a tRNA is mischarged with the wrong amino acid, what is the most likely consequence during translation?

Accepted Answer

The wrong amino acid will be incorporated into the growing polypeptide chain.

Question 20

Which of the following is true about the directionality of RNA synthesis during transcription?

Accepted Answer

RNA is synthesized in the 5' to 3' direction.

Gene Expression and Its Regulation: Transcription, Translation, and Control in Prokaryotes and Eukaryotes

Study Guide - Practice Questions