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 template strand has the sequence 5'-TACGGTACG-3'. What is the corresponding mRNA sequence after transcription (assume no introns)?

Accepted Answer

5'-AUGCCAUGC-3'

Question 3

Which of the following statements about RNA polymerase is TRUE?

Accepted Answer

RNA polymerase synthesizes RNA in the 5'→3' direction.

Question 4

In prokaryotic transcription, what is the role of the sigma factor?

Accepted Answer

It recognizes promoter sequences and helps RNA polymerase bind to DNA.

Question 5

Which of the following is a post-transcriptional modification that occurs in eukaryotes but not in prokaryotes?

Accepted Answer

Addition of a 5' cap to mRNA

Question 6

A mutation changes the codon 5'-UUA-3' to 5'-UUG-3'. Both codons code for leucine. What type of mutation is this?

Accepted Answer

Silent mutation

Question 7

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

Accepted Answer

Aminoacyl-tRNA synthetase

Question 8

What would be the effect if an aminoacyl-tRNA synthetase misloaded a tRNA with the wrong amino acid?

Accepted Answer

The resulting protein would have an incorrect amino acid, potentially altering its function.

Question 9

Which of the following best describes an operon?

Accepted Answer

A group of genes regulated by a single promoter and transcribed together.

Question 10

In the lac operon, what happens when lactose is present and glucose is absent?

Accepted Answer

The CAP-cAMP complex forms, enhancing transcription of the lac operon.

Question 11

Which of the following is a key difference between gene regulation in prokaryotes and eukaryotes?

Accepted Answer

Prokaryotes use operons, while eukaryotes typically regulate genes individually.

Question 12

Which of the following is TRUE about chromatin remodeling in eukaryotes?

Accepted Answer

Histone acetyltransferases (HATs) add acetyl groups, loosening chromatin structure.

Question 13

Which of the following best explains alternative splicing?

Accepted Answer

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

Question 14

A scientist uses replica plating to identify bacterial mutants that cannot metabolize lactose. What is the main advantage of this technique?

Accepted Answer

It allows the identification of mutants without killing them.

Question 15

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

Accepted Answer

Phosphorylation of a protein

Question 16

Which of the following best describes a repressible operon?

Accepted Answer

An operon that is usually on but can be turned off when a specific molecule is present.

Question 17

What is the role of release factors during translation?

Accepted Answer

They recognize stop codons and terminate translation.

Question 18

Which of the following is a mechanism of RNA interference?

Accepted Answer

Small RNAs bind to mRNA and promote its degradation.

Question 19

Which of the following best describes 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.

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

Study Guide - Practice Questions