Question 1

Which of the following statements best describes the role of sigma protein in bacterial transcription initiation?

Accepted Answer

Sigma protein recognizes promoter regions and orients RNA polymerase to the correct DNA strand.

Question 2

During transcription in bacteria, which sequence is typically found about 10 bases upstream of the transcription start site and is crucial for promoter recognition?

Accepted Answer

The TATAAT box

Question 3

Which of the following is a key difference between bacterial and eukaryotic transcription termination?

Accepted Answer

Bacteria terminate transcription when a hairpin structure forms in the RNA, while eukaryotes use a poly(A) signal and RNA cleavage.

Question 4

A mutation in the TATAAT box of a bacterial promoter would most likely result in which of the following?

Accepted Answer

Reduced recognition of the promoter by sigma protein, leading to decreased transcription initiation.

Question 5

Which of the following best explains why RNA polymerase does not require a primer to begin transcription, unlike DNA polymerase?

Accepted Answer

RNA polymerase can initiate RNA synthesis de novo by binding directly to the promoter region.

Question 6

Which of the following events occurs during the elongation phase of bacterial transcription?

Accepted Answer

RNA polymerase adds nucleotides to the 3' end of the growing RNA strand.

Question 7

In eukaryotic cells, which of the following is NOT a step in the processing of pre-mRNA?

Accepted Answer

Binding of sigma protein to the promoter.

Question 8

A researcher discovers a eukaryotic mRNA molecule that lacks a poly(A) tail. Which of the following is the most likely consequence for this mRNA?

Accepted Answer

It will be rapidly degraded in the cytoplasm.

Question 9

Which of the following best describes the function of the spliceosome in eukaryotic cells?

Accepted Answer

It removes introns from the primary RNA transcript and joins exons together.

Question 10

A genetic disorder results in the failure to remove introns from pre-mRNA in eukaryotic cells. What is the most likely outcome?

Accepted Answer

The mature mRNA will contain noncoding sequences, potentially leading to nonfunctional proteins.

Question 11

Which of the following is a direct result of alternative splicing in eukaryotes?

Accepted Answer

Multiple different proteins can be produced from a single gene.

Question 12

Which of the following equations correctly represents the direction of RNA synthesis by RNA polymerase?

Accepted Answer

$$5' \rightarrow 3'$$

Question 13

A bacterial cell is exposed to a chemical that specifically disrupts the formation of hairpin structures in RNA. What is the most likely effect on transcription?

Accepted Answer

Transcription termination will fail, resulting in abnormally long RNA transcripts.

Question 14

Which of the following best explains why mature eukaryotic mRNAs contain untranslated regions (UTRs) at both ends?

Accepted Answer

UTRs play roles in mRNA stability, localization, and translation regulation.

Question 15

Which of the following is true regarding the difference between the coding and template strands of DNA during transcription?

Accepted Answer

The template strand is complementary to the mRNA, while the coding strand matches the mRNA sequence (except U for T).

Question 16

Which of the following best describes the function of the 5' cap added to eukaryotic mRNA?

Accepted Answer

It enables ribosomes to bind and protects the mRNA from degradation.

Question 17

A scientist is studying a eukaryotic gene and finds that the mature mRNA is much shorter than the DNA sequence of the gene. What is the most likely explanation?

Accepted Answer

The gene contains introns that are removed during RNA processing.

Question 18

Which of the following is a consequence of the discovery of split genes in eukaryotes?

Accepted Answer

It revealed that genes can contain noncoding regions (introns) that are removed during RNA processing.

Transcription, RNA Processing, and Translation: Study Notes

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