Q: Which of the following best explains why DNA polymerase cannot initiate synthesis of a new DNA strand on its own?

It requires a free $$3'\text{OH}$$ group to add nucleotides

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

The leading strand is synthesized continuously in the $$5' \to 3'$$ direction

Question 1

During DNA replication in bacteria, which enzyme is responsible for relieving the torsional strain that builds up ahead of the replication fork as the DNA unwinds?

Accepted Answer

DNA gyrase

Question 2

Which of the following is NOT required for DNA replication but IS required for RNA synthesis?

Accepted Answer

A primer

Question 3

A mutation in the gene encoding DNA ligase would most directly affect which process during DNA replication?

Accepted Answer

Joining Okazaki fragments on the lagging strand

Question 4

Which of the following best explains why DNA polymerase cannot initiate synthesis of a new DNA strand on its own?

Accepted Answer

It requires a free $$3'	ext{OH}$$ group to add nucleotides

Question 5

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 $$5' 	o 3'$$ direction

Question 6

What provides the energy for the addition of a nucleotide during DNA synthesis?

Accepted Answer

Hydrolysis of pyrophosphate ($$PP_i) $$released from the incoming dNTP

Question 7

A bacterial cell is exposed to a chemical that specifically inhibits the function of primase. What immediate effect would this have on DNA replication?

Accepted Answer

Synthesis of RNA primers would stop, halting initiation of Okazaki fragments

Question 8

Which of the following is a function of the sigma ($$\sigma) $$factor in bacterial transcription?

Accepted Answer

It directs RNA polymerase to specific promoter sequences

Question 9

A mutation causes the loss of the $$3'	o5'$$ exonuclease activity in DNA polymerase III. What is the most likely consequence?

Accepted Answer

The mutation rate during DNA replication would increase

Question 10

Which of the following best describes the function of the Shine-Dalgarno sequence in prokaryotes?

Accepted Answer

It helps align the ribosome with the start codon on mRNA for translation initiation

Question 11

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

Accepted Answer

The strand that is complementary to the RNA product

Question 12

Which of the following is NOT a difference between DNA polymerase and RNA polymerase?

Accepted Answer

The direction in which the template is read

Question 13

A bacterial gene is transcribed using the sigma-70 factor, which recognizes the consensus sequences $$TTGACA at$$ $$-35$$ and $$TATAAT at$$ $$-10. If a $$mutation changes the $$-10$$ sequence to $$TATGGT$$, what is the most likely effect?

Accepted Answer

Transcription initiation at this promoter would decrease

Question 14

Which of the following statements about Okazaki fragments is correct?

Accepted Answer

They are short DNA fragments synthesized on the lagging strand

Question 15

Which of the following is a direct result of the hydrolysis of pyrophosphate ($$PP_i) $$during DNA synthesis?

Accepted Answer

The reaction is driven forward, making DNA synthesis energetically favorable

Question 16

A bacterium is found to have a mutation that prevents the removal of RNA primers from Okazaki fragments. Which enzyme is most likely defective?

Accepted Answer

DNA polymerase I

Question 17

Which of the following best explains why some viruses with RNA genomes use RNA-dependent RNA polymerase for replication?

Accepted Answer

They do not have a DNA stage and must replicate their RNA directly

Question 18

Which of the following is NOT a component of the modern 'Central Dogma' of molecular biology?

Accepted Answer

Protein makes RNA

Question 19

A bacterial cell contains several different sigma factors. What is the main advantage of this arrangement?

Accepted Answer

It allows the cell to transcribe different sets of genes in response to environmental changes

Question 20

Which of the following is the correct order of events during bacterial DNA replication?

Accepted Answer

Helicase unwinds DNA, primase synthesizes RNA primer, DNA polymerase synthesizes DNA, ligase joins fragments

DNA Replication, Transcription, and RNA Polymerase in Bacteria: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard