Question 1

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 2

During DNA replication, which enzyme is responsible for synthesizing the new DNA strand by adding nucleotides to a pre-existing primer?

Accepted Answer

DNA polymerase

Question 3

In prokaryotic cells, where does DNA replication begin?

Accepted Answer

At a single origin of replication on the circular chromosome

Question 4

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

Accepted Answer

The leading strand is synthesized continuously in the 5' to 3' direction, while the lagging strand is synthesized discontinuously as Okazaki fragments.

Question 5

A mutation occurs in the gene encoding DNA ligase in a bacterium. Which process would be most directly affected?

Accepted Answer

Joining of Okazaki fragments on the lagging strand during DNA replication

Question 6

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

Accepted Answer

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

Question 7

Which of the following is NOT a component of a nucleotide in nucleic acids?

Accepted Answer

A sulfur-containing side chain

Question 8

During transcription in prokaryotes, what is the role of the sigma factor?

Accepted Answer

It helps RNA polymerase recognize and bind to the promoter sequence.

Question 9

Which of the following best describes the function of tRNA during translation?

Accepted Answer

It brings specific amino acids to the ribosome by matching its anticodon to the mRNA codon.

Question 10

A researcher is studying a gene that is only expressed when a specific sugar is present in the environment. This is an example of:

Accepted Answer

Gene regulation in response to environmental signals

Question 11

Which of the following equations correctly represents the directionality of DNA synthesis?

Accepted Answer

$$5' \rightarrow 3'$$

Question 12

In the process of transcription, which strand of DNA serves as the template for RNA synthesis?

Accepted Answer

The antisense (template) strand

Question 13

Which of the following is a key difference between prokaryotic and eukaryotic genomes?

Accepted Answer

Prokaryotic genomes are typically circular and have a single origin of replication, while eukaryotic genomes are linear and have multiple origins of replication.

Question 14

Which of the following best describes the function of messenger RNA (mRNA)?

Accepted Answer

It carries the genetic information from DNA to the ribosome for protein synthesis.

Question 15

A mutation changes a codon from UAU (tyrosine) to UAA. What is the likely result of this mutation?

Accepted Answer

Translation will terminate prematurely because UAA is a stop codon.

Question 16

Which of the following steps occurs first during DNA replication?

Accepted Answer

Unwinding of the DNA double helix by helicase

Question 17

Which of the following is true regarding the direction of RNA synthesis during transcription?

Accepted Answer

RNA is synthesized in the $$5' \rightarrow 3'$$ direction.

Question 18

Which of the following best explains why Okazaki fragments are formed during DNA replication?

Accepted Answer

DNA polymerase can only synthesize DNA in the $$5' \rightarrow 3'$$ direction, so the lagging strand is synthesized discontinuously.

Question 19

A bacterial cell is exposed to a chemical that inhibits primase. What is the most immediate effect on DNA replication?

Accepted Answer

RNA primers will not be synthesized, preventing DNA polymerase from initiating DNA synthesis.

Question 20

Which of the following statements about the genetic code is correct?

Accepted Answer

It is nearly universal, with most organisms using the same codons to specify amino acids.

Microbial Genetics: DNA Structure, Replication, Transcription, and Translation

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