Question 1

Which statement best describes the 'central dogma' of molecular biology?

Accepted Answer

Genetic information flows from DNA to RNA to protein.

Question 2

During DNA replication, which enzyme is responsible for unwinding the double helix?

Accepted Answer

Helicase

Question 3

If a DNA strand has the sequence 5'-ATCGGTA-3', what is the complementary sequence?

Accepted Answer

3'-TAGCCAT-5'

Question 4

Which of the following best explains why DNA polymerase requires a primer?

Accepted Answer

DNA polymerase can only add nucleotides to an existing 3' hydroxyl group.

Question 5

Which enzyme is responsible for synthesizing RNA primers during DNA replication?

Accepted Answer

Primase

Question 6

A mutation changes a DNA base from G to T. Which DNA repair mechanism can immediately correct this error?

Accepted Answer

Mismatch repair

Question 7

During transcription, which strand of DNA is used as the template?

Accepted Answer

The non-coding (template) strand

Question 8

Which of the following enzymes is responsible for joining Okazaki fragments on the lagging strand?

Accepted Answer

DNA ligase

Question 9

In prokaryotes, which enzyme synthesizes the majority of DNA during replication?

Accepted Answer

DNA polymerase III

Question 10

Which of the following best describes the difference between DNA polymerase and RNA polymerase?

Accepted Answer

DNA polymerase synthesizes DNA using a DNA template, while RNA polymerase synthesizes RNA using a DNA template.

Question 11

A bacterial cell uses alternate sigma factors to regulate gene expression. What is the most likely outcome?

Accepted Answer

The cell can express different sets of genes in response to environmental changes.

Question 12

Which of the following is true about the leading and lagging strands during DNA replication?

Accepted Answer

The leading strand is synthesized continuously, while the lagging strand is synthesized in short fragments.

Question 13

Given the DNA sequence 5'-ATGCGTACG-3', what would be the mRNA sequence transcribed from it?

Accepted Answer

3'-UACGCAUGC-5'

Question 14

Which of the following best describes the role of ribosomes in translation?

Accepted Answer

Ribosomes catalyze the formation of peptide bonds between amino acids.

Question 15

Which of the following is a function of the enzyme gyrase during DNA replication?

Accepted Answer

Relieves supercoiling ahead of the replication fork

Question 16

A mutation in the gene encoding the lac repressor prevents it from binding to the operator. What is the most likely effect?

Accepted Answer

The lac operon will be constitutively expressed.

Question 17

Which of the following equations correctly represents the base pairing rules in DNA?

Accepted Answer

$$A = T$$ and $$G = C$$

Question 18

Which process is responsible for removing introns from eukaryotic pre-mRNA?

Accepted Answer

RNA splicing

Question 19

Which of the following best describes the function of a repressor protein in gene regulation?

Accepted Answer

It binds to the operator to block transcription.

Question 20

A bacterium senses a change in its environment and alters gene expression using a two-component regulatory system. Which statement best describes this system?

Accepted Answer

It involves a sensor kinase and a response regulator.

DNA Replication, Transcription, and Gene Regulation: Key Concepts and Enzymes

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