Question 1

Which of the following best describes the process of transcription?

Accepted Answer

DNA template-directed biosynthesis of RNA

Question 2

In the operon model, what is the function of the inducer molecule?

Accepted Answer

It binds to the repressor, causing it to become unable to bind the operator

Question 3

Which property of mRNA is illustrated by its radioactivity profile being heterogenous in a pulse-labeling sedimentation experiment?

Accepted Answer

mRNA is heterogenous in size

Question 4

During a sedimentation experiment using a sucrose gradient, which property of RNA determines how far it migrates down the centrifuge tube?

Accepted Answer

The size of the RNA molecule

Question 5

Which inhibitor is used to distinguish between bacterial and eukaryotic RNA polymerases, and what is its effect?

Accepted Answer

α-Amanitin, which has different effects on the three eukaryotic RNA polymerases

Question 6

Which subunit of E. coli RNA polymerase is responsible for promoter recognition?

Accepted Answer

σ subunit

Question 7

What is the role of the sigma factor in the E. coli RNA polymerase holoenzyme?

Accepted Answer

It directs RNA polymerase to the promoter site for initiation

Question 8

Which sequence in bacterial DNA is most closely associated with the initiation of transcription?

Accepted Answer

The -35 and -10 regions

Question 9

Factor-dependent termination of transcription in bacteria involves which protein, and what is its primary function?

Accepted Answer

ϱ protein, which unwinds the RNA-DNA hybrid and releases the transcript

Question 10

Which eukaryotic RNA polymerase is responsible for transcribing protein-coding genes?

Accepted Answer

RNA polymerase II

Question 11

Which four residues chelate the Zn ion in a zinc finger protein?

Accepted Answer

Cysteine 6, Cysteine 3, Histidine 23, Histidine 19

Question 12

Where is the TATA box located relative to the transcription start site in eukaryotes?

Accepted Answer

Upstream of the transcription start site

Question 13

Which of the following best describes enhancer regions in eukaryotic transcription?

Accepted Answer

They are distant DNA sequences that bind protein factors to affect gene transcription

Question 14

Acetylation of histones affects transcription by:

Accepted Answer

Increasing the rate of gene transcription

Question 15

On which amino acid residue does acetylation occur in histone proteins?

Accepted Answer

Lysine

Question 16

What is the primary function of elongation factors during eukaryotic transcription?

Accepted Answer

To aid RNA polymerase II in passing regions where transcription pauses

Question 17

During eukaryotic transcription termination, what signal is recognized by endonucleases to cleave the pre-mRNA?

Accepted Answer

AAUAAA

Question 18

What is the main purpose of the polyA tail added to eukaryotic mRNA?

Accepted Answer

To increase mRNA stability and facilitate transport to the cytosol

Question 19

A mutation causes the loss of acetylation on histone lysine residues. What is the most likely effect on gene expression?

Accepted Answer

Gene expression will decrease due to tighter DNA-histone interactions

Question 20

Which of the following equations correctly represents the nucleophilic attack during RNA chain elongation?

Accepted Answer

$$	ext{3'-OH (of sugar group of first nucleotide)} + 	ext{\alpha-phosphate (of second nucleotide)} ightarrow 	ext{phosphodiester bond}$$

Biochemistry Study Guide: Transcription and RNA Synthesis

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