Question 1

Which of the following best describes the process of transcription in cells?

Accepted Answer

DNA template-directed biosynthesis of RNA

Question 2

In the operon model proposed by Jacob and Monod, what is the primary function of the operator region?

Accepted Answer

It is the DNA sequence where regulatory proteins bind to control transcription of structural genes

Question 3

Which of the following statements about RNA polymerase in prokaryotes is correct?

Accepted Answer

The core enzyme requires the sigma ($$\sigma) $$factor for promoter recognition

Question 4

Which of the following best explains why RNA is denser than DNA?

Accepted Answer

RNA contains a 2'-hydroxyl group, increasing its mass and density compared to DNA

Question 5

During the initiation of transcription in bacteria, what is the role of the sigma ($$\sigma) $$factor?

Accepted Answer

It recognizes and binds to promoter sequences, directing RNA polymerase to the initiation site

Question 6

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

Accepted Answer

Eukaryotic transcription occurs in the nucleus and involves chromatin remodeling

Question 7

Which of the following best describes the function of the TATA box in eukaryotic promoters?

Accepted Answer

It is a conserved DNA sequence that helps position RNA polymerase II for transcription initiation

Question 8

A mutation in the gene encoding the Rho ($$\rho) $$factor in E. coli would most likely affect which aspect of transcription?

Accepted Answer

Termination of transcription at certain sites

Question 9

Which of the following correctly matches the eukaryotic RNA polymerase with its primary function?

Accepted Answer

RNA polymerase III: synthesis of tRNA and some small RNAs

Question 10

Which of the following best explains the effect of histone acetylation on gene expression?

Accepted Answer

Acetylation of histones neutralizes lysine residues, weakening DNA-histone interactions and promoting transcription

Question 11

A researcher uses chromatin immunoprecipitation (ChIP) to study DNA-protein interactions. Which of the following best describes the principle of this technique?

Accepted Answer

It uses antibodies to isolate DNA fragments bound to specific proteins

Question 12

Which of the following steps occurs first during the elongation phase of transcription?

Accepted Answer

Nucleophilic attack by the 3'-OH of the first nucleotide on the $$\alpha-$$phosphate of the second nucleotide

Question 13

Which of the following is a direct consequence of alternative splicing in eukaryotic cells?

Accepted Answer

Production of multiple protein isoforms from a single gene

Question 14

A patient is found to have a mutation that prevents the addition of a 5'-cap to pre-mRNA. Which of the following is the most likely consequence?

Accepted Answer

The mRNA will be rapidly degraded and inefficiently translated

Question 15

Which of the following best describes the function of the poly(A) tail added to eukaryotic mRNA?

Accepted Answer

It increases mRNA stability and influences its half-life

Question 16

A scientist is studying a gene that is highly expressed only when its promoter region is acetylated. Which of the following best explains this observation?

Accepted Answer

Acetylation of histones in the promoter region loosens chromatin structure, allowing transcription factors to access DNA

Question 17

Which of the following is a key feature of factor-independent (intrinsic) termination of transcription in bacteria?

Accepted Answer

A stem-loop structure forms in the RNA, followed by a run of uracils

Question 18

During eukaryotic transcription, what is the role of enhancer regions?

Accepted Answer

They increase transcription by binding activator proteins that interact with the core transcription complex via DNA looping

Question 19

A mutation in the gene encoding U1 snRNP would most directly affect which process?

Accepted Answer

Splicing of pre-mRNA to remove introns

Transcription and Posttranscriptional Processes in Biochemistry

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