Question 1

Which of the following statements best describes the difference between prokaryotic and eukaryotic genomes?

Accepted Answer

Eukaryotic genomes are organized into multiple linear chromosomes housed in a nucleus, while prokaryotic genomes are typically a single circular chromosome located in the nucleoid region.

Question 2

A mutation changes a codon from $$	ext{CGA} ($$arginine) to $$	ext{UGA} ($$stop codon). What type of mutation is this, and what is its likely effect?

Accepted Answer

Nonsense mutation; results in premature termination of translation and a truncated protein.

Question 3

Which enzyme is responsible for unwinding the DNA double helix during DNA replication?

Accepted Answer

Helicase

Question 4

During DNA replication, why is the lagging strand synthesized in Okazaki fragments?

Accepted Answer

Because DNA polymerase can only add nucleotides to the 3' end, and the lagging strand template is oriented 5' to 3' away from the fork, requiring discontinuous synthesis.

Question 5

Which of the following best explains why the genetic code is described as 'redundant'?

Accepted Answer

Multiple codons can code for the same amino acid.

Question 6

A bacterial cell acquires a gene for antibiotic resistance from its environment without direct contact with another cell. What is this process called?

Accepted Answer

Transformation

Question 7

Which of the following is a function of small noncoding RNAs in post-transcriptional regulation?

Accepted Answer

They bind to mRNA, tagging it for destruction or preventing ribosome binding.

Question 8

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 9

Which of the following is true regarding plasmids?

Accepted Answer

They are pieces of DNA that exist outside the chromosomal DNA and often confer advantages such as antibiotic resistance.

Question 10

A scientist exposes bacterial cells to UV light, which causes thymine dimers. Which DNA repair mechanism is most likely to fix this damage?

Accepted Answer

Excision repair

Question 11

Which of the following is a key difference between generalized and specialized transduction?

Accepted Answer

Generalized transduction can transfer any gene from the donor, while specialized transduction transfers only genes near the phage integration site.

Question 12

Which of the following best describes a frameshift mutation?

Accepted Answer

A mutation caused by insertion or deletion of bases not in multiples of three, altering the reading frame.

Question 13

Which of the following is NOT a step in transcription?

Accepted Answer

Translation

Question 14

Which of the following is a real-life example of horizontal gene transfer impacting human health?

Accepted Answer

A bacterium acquiring antibiotic resistance genes via conjugation, leading to the spread of drug-resistant infections.

Question 15

Which of the following statements about DNA directionality is correct?

Accepted Answer

DNA is synthesized in the 5' to 3' direction, with one end having a 5' phosphate and the other a 3' hydroxyl group.

Question 16

Which of the following is a post-translational modification that may be required for a protein to function?

Accepted Answer

Addition of sugars or lipids to the protein

Question 17

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

Accepted Answer

It brings the correct amino acid to the ribosome by matching its anticodon to the mRNA codon.

Question 18

Which of the following is an example of a chemical mutagen?

Accepted Answer

Arsenic

Question 19

What is the main advantage of alternative splicing in eukaryotic cells?

Accepted Answer

It increases the number of proteins that can be produced from a single gene.

Question 20

Which of the following best describes the function of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments together by forming phosphodiester bonds.

Microbial Genetics: Structure, Function, and Variation

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