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

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

Accepted Answer

Nonsense mutation

Question 3

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

Accepted Answer

Helicase

Question 4

In the lac operon, what happens when lactose is present in the environment?

Accepted Answer

Allolactose binds to the repressor, inactivating it and allowing transcription.

Question 5

Which of the following best explains why bacterial DNA replication is considered bidirectional?

Accepted Answer

Replication proceeds in two directions from a single origin.

Question 6

A chemical mutagen causes adenine to pair with cytosine instead of thymine. Which mutagen is most likely responsible?

Accepted Answer

Nitrous acid

Question 7

Which of the following statements about plasmids is TRUE?

Accepted Answer

Plasmids may carry genes for antibiotic resistance and can be transferred between cells.

Question 8

During translation, what is the role of tRNA?

Accepted Answer

It carries amino acids to the ribosome and matches them to the mRNA codon.

Question 9

Which process is illustrated by the following scenario: A bacterium takes up naked DNA from its environment and incorporates it into its chromosome?

Accepted Answer

Transformation

Question 10

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

Accepted Answer

The reading frame of the mRNA is altered, changing many downstream amino acids.

Question 11

Which of the following best describes the function of the operator in an operon?

Accepted Answer

It is the DNA segment where a repressor can bind to regulate transcription.

Question 12

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

Accepted Answer

In eukaryotes, mRNA is processed to remove introns before translation.

Question 13

Which of the following is an example of horizontal gene transfer?

Accepted Answer

A bacterium acquiring a plasmid from another bacterium via conjugation.

Question 14

Which of the following codons is a start codon in translation?

Accepted Answer

$$\mathrm{AUG}$$

Question 15

A bacterium exposed to UV light develops thymine dimers in its DNA. Which enzyme can directly repair this damage using visible light?

Accepted Answer

Photolyase

Question 16

Which of the following best describes the function of the R-determinant on an R plasmid?

Accepted Answer

It encodes antibiotic resistance genes.

Question 17

Which of the following is TRUE about generalized transduction?

Accepted Answer

Random bacterial DNA fragments are packaged into phage particles and transferred to a recipient cell.

Question 18

Which of the following is a property of the genetic code that allows silent mutations to occur?

Accepted Answer

The code is degenerate, meaning multiple codons can code for the same amino acid.

Question 19

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

Accepted Answer

DNA polymerase can only add nucleotides to the 3' end, so the lagging strand is synthesized discontinuously.

(Chapter 8) Microbial Genetics: Structure, Function, and Transfer of Genetic Material

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