Question 1

Which of the following best describes the relationship between genotype and phenotype in a microbial cell?

Accepted Answer

Genotype is the collection of genes inherited, and phenotype is the observable traits resulting from gene expression.

Question 2

A scientist isolates a circular DNA molecule from a bacterium that is separate from the main chromosome. What is this molecule most likely called?

Accepted Answer

Plasmid

Question 3

Which of the following correctly pairs the nitrogenous bases in DNA according to complementary base pairing?

Accepted Answer

Adenine pairs with Thymine; Guanine pairs with Cytosine

Question 4

During DNA replication, which enzyme is responsible for unwinding the double helix and breaking hydrogen bonds between base pairs?

Accepted Answer

Helicase

Question 5

What is the primary function of DNA polymerase I during DNA replication?

Accepted Answer

Removing RNA primers and replacing them with DNA nucleotides

Question 6

A mutation occurs in a bacterial gene, changing a single nucleotide and resulting in a premature stop codon. What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 7

Which of the following best explains why silent mutations often do not affect the protein produced?

Accepted Answer

The redundancy of the genetic code and wobble in the third codon position allow the same amino acid to be specified.

Question 8

Which equation best represents the semiconservative model of DNA replication?

Accepted Answer

Each new DNA molecule consists of one original strand and one new strand: $$	ext{New DNA} = 	ext{Original Strand} + 	ext{New Strand}$$

Question 9

Which of the following is NOT a product of transcription?

Accepted Answer

DNA polymerase

Question 10

A bacterium is exposed to UV light, causing DNA damage. Which repair mechanism is most likely to be activated by sunlight to fix this damage?

Accepted Answer

Photoreactivation

Question 11

Which of the following statements about the lac operon is correct?

Accepted Answer

Lactose acts as an inducer, allowing transcription of the operon when present.

Question 12

Which of the following best describes the process of transformation in bacteria?

Accepted Answer

Acquisition of DNA fragments from the environment by a competent cell

Question 13

A frameshift mutation occurs when:

Accepted Answer

One or more nucleotides are added or removed, altering the reading frame

Question 14

Which of the following is required for conjugation to occur between two bacterial cells?

Accepted Answer

At least one cell must produce a pilus

Question 15

In eukaryotic cells, what is the function of spliceosomes during mRNA processing?

Accepted Answer

They remove introns and join exons to produce mature mRNA.

Question 16

Which of the following best explains the significance of the wobble phenomenon in genetic coding?

Accepted Answer

It allows for variability in the third nucleotide of a codon, supporting redundancy and reducing the impact of mutations.

Question 17

Which of the following equations correctly represents the complementary base pairing in DNA?

Accepted Answer

$$A 	ext{ pairs with } T; G 	ext{ pairs with } C$$

Question 18

Which codon always signals the start of translation in protein synthesis?

Accepted Answer

$$AUG$$

Question 19

A bacterium lacking the lac operon would be unable to:

Accepted Answer

Metabolize lactose

Question 20

Which of the following is a major difference between RNA and DNA nucleotides?

Accepted Answer

RNA nucleotides contain ribose and uracil, while DNA nucleotides contain deoxyribose and thymine.

Principles of Microbial Genetics: Structure, Function, and Regulation

Study Guide - Practice Questions