Question 1

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

Accepted Answer

tRNA carries amino acids to the ribosome and matches its anticodon with the codon on mRNA.

Question 2

Which bond forms the sugar-phosphate backbone of DNA?

Accepted Answer

Phosphodiester bond

Question 3

A mutation changes a DNA codon from TAT to TAA. What type of mutation is this, and what is its likely effect on the protein?

Accepted Answer

Nonsense mutation; introduces a premature stop codon

Question 4

Which of the following statements about the directionality of nucleic acid synthesis is correct?

Accepted Answer

Both DNA and RNA are synthesized in the 5' to 3' direction.

Question 5

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

Accepted Answer

DNA helicase

Question 6

In the context of horizontal gene transfer, which mechanism involves the uptake of naked DNA from the environment?

Accepted Answer

Transformation

Question 7

Which of the following is a unique feature of RNA compared to DNA?

Accepted Answer

RNA contains uracil instead of thymine.

Question 8

A patient is diagnosed with ETEC infection. The genes for its toxins are found on plasmids. What is the most likely explanation for how these genes spread among bacteria?

Accepted Answer

Horizontal gene transfer via conjugation

Question 9

Which of the following codons serves as the start codon in translation and what amino acid does it code for?

Accepted Answer

$$	ext{AUG}$$; Methionine

Question 10

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 11

Which of the following is NOT a function of the sugar-phosphate backbone in DNA?

Accepted Answer

Encoding genetic information

Question 12

Which of the following best describes the difference between leading and lagging strand synthesis during DNA replication?

Accepted Answer

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

Question 13

Which of the following is a consequence of a frameshift mutation?

Accepted Answer

The reading frame of the gene is altered, potentially changing every amino acid downstream.

Question 14

Which of the following best explains why transcription and translation can occur simultaneously in prokaryotes but not in eukaryotes?

Accepted Answer

Prokaryotes lack a nucleus, so both processes occur in the cytoplasm.

Question 15

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

Accepted Answer

Joining Okazaki fragments on the lagging strand

Question 16

A patient with necrotizing fasciitis caused by Streptococcus pyogenes is being treated. Which virulence factor allows the bacteria to evade phagocytosis?

Accepted Answer

Capsule and M proteins

Question 17

Which of the following best describes the relationship between genotype and phenotype?

Accepted Answer

Phenotype is determined by the expression of specific genes in response to environmental conditions.

Question 18

Which of the following is true regarding the base pairing in DNA?

Accepted Answer

Adenine pairs with thymine and guanine pairs with cytosine.

Question 19

Which of the following best explains why antibiotic therapy is not usually recommended for EHEC infections?

Accepted Answer

Antibiotics can increase the risk of endotoxic shock by causing massive toxin release.

Biochemistry of the Genome & Mechanisms of Microbial Genetics: Core Concepts and Clinical Applications

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