Question 1

Which of the following statements best distinguishes DNA replication from transcription in terms of their biological consequences?

Accepted Answer

DNA replication creates a permanent copy that is inherited by future generations, while transcription produces transient RNA molecules that are not inherited.

Question 2

In prokaryotic transcription, which strand of DNA is used as the template for RNA synthesis?

Accepted Answer

The template strand, which is complementary to the mRNA sequence.

Question 3

A mutation in the -10 region (Pribnow box/TATA box) of a prokaryotic promoter is most likely to:

Accepted Answer

Alter the quantity of RNA produced from the affected gene without changing the protein sequence.

Question 4

Which of the following best describes the role of sigma factors in prokaryotic transcription?

Accepted Answer

Sigma factors confer specificity to RNA polymerase, enabling recognition of promoter consensus sequences.

Question 5

A bacterial cell is exposed to high temperatures. Which sigma factor is most likely to be upregulated, and what is its function?

Accepted Answer

Sigma factor oH; it controls expression of heat-shock genes.

Question 6

Which of the following is a key difference between strong and weak prokaryotic promoters?

Accepted Answer

Strong promoters have sequences more similar to the consensus, increasing RNA polymerase affinity.

Question 7

During prokaryotic transcription, what is the primary function of the transcription bubble?

Accepted Answer

It separates the DNA strands, enabling RNA polymerase to read the template strand and synthesize RNA.

Question 8

Which equation correctly represents the directionality of RNA synthesis by RNA polymerase?

Accepted Answer

$$5' \rightarrow 3'$$

Question 9

A mutation increases the similarity of a promoter sequence to the consensus sequence. What is the most likely effect?

Accepted Answer

Increased RNA polymerase binding and elevated gene expression.

Question 10

Which of the following best describes a polycistronic mRNA?

Accepted Answer

An mRNA molecule that contains multiple ORFs, each translated into a different protein; common in prokaryotes.

Question 11

Which of the following is a direct consequence of abortive initiation during prokaryotic transcription?

Accepted Answer

Short RNA fragments are repeatedly synthesized and released until RNA polymerase escapes the promoter.

Question 12

Which structural feature of a strong intrinsic terminator in prokaryotic transcription is essential for termination?

Accepted Answer

A stem-loop (hairpin) structure rich in G-C pairs followed by a U-rich region.

Question 13

Which protein is required for termination at weak terminators in prokaryotic transcription?

Accepted Answer

Rho protein

Question 14

If a mutation occurs in the sigma factor gene that alters its DNA-binding domain, what is the most likely outcome?

Accepted Answer

All genes controlled by that sigma factor will have altered expression.

Question 15

Which of the following best explains why transcription initiation is often the rate-limiting step in gene expression?

Accepted Answer

It requires assembly of the transcription apparatus and is tightly regulated to conserve energy.

Question 16

Which of the following is NOT a function of the core RNA polymerase enzyme in prokaryotes?

Accepted Answer

Specific recognition of promoter sequences

Question 17

A researcher observes a 'Christmas-tree-like' structure under an electron microscope when examining DNA. What does this structure most likely represent?

Accepted Answer

Multiple RNA polymerases transcribing a highly expressed gene, with nascent RNA chains radiating outward.

Question 18

Which of the following equations correctly represents the base pairing between the template DNA strand and the newly synthesized RNA during transcription?

Accepted Answer

$$	ext{DNA}: 3'	ext{-}ATGCAT	ext{-}5' ightarrow 	ext{RNA}: 5'	ext{-}UACGUA	ext{-}3'$$

Question 19

Which of the following is a real-world application of understanding promoter strength in biotechnology?

Accepted Answer

Designing synthetic promoters to control gene expression levels in genetically engineered bacteria.

Gene Expression and Transcription: Prokaryotic and Eukaryotic Mechanisms

Study Guide - Practice Questions

Study Guide - Flashcards