Question 1

Which of the following best describes the relationship between genome, chromosome, and gene in a eukaryotic cell?

Accepted Answer

A genome consists of all chromosomes, each chromosome contains many genes.

Question 2

What is the main structural difference between prokaryotic and eukaryotic chromosomes?

Accepted Answer

Prokaryotic chromosomes are circular and usually singular, while eukaryotic chromosomes are linear and multiple.

Question 3

Which extrachromosomal genetic element is commonly found in bacteria and may carry genes conferring antibiotic resistance?

Accepted Answer

Plasmid

Question 4

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

Accepted Answer

DNA contains deoxyribose, while RNA contains ribose.

Question 5

What type of covalent bond links the monomers in nucleic acids?

Accepted Answer

Phosphodiester bond

Question 6

In the process of DNA replication, what is the role of helicase?

Accepted Answer

Unwinds the DNA double helix

Question 7

Which nitrogenous base is found only in RNA and not in DNA?

Accepted Answer

Uracil

Question 8

What is the advantage of supercoiled DNA in bacterial cells?

Accepted Answer

It allows DNA to occupy less space within the cell.

Question 9

Why is DNA replication described as semiconservative?

Accepted Answer

Each new DNA molecule contains one old strand and one new strand.

Question 10

During transcription in bacteria, what is the function of the sigma factor?

Accepted Answer

It recognizes promoter sequences and helps RNA polymerase bind to DNA.

Question 11

Which site on the ribosome receives the charged tRNA during translation?

Accepted Answer

A site

Question 12

What is the Shine-Dalgarno sequence and where is it found?

Accepted Answer

A ribosome binding site found in prokaryotic mRNA

Question 13

Which antibiotic targets bacterial translation by preventing the binding of aminoacyl-tRNA to the ribosome?

Accepted Answer

Tetracycline

Question 14

Why does tetracycline not affect eukaryotic cells under normal conditions?

Accepted Answer

Eukaryotic ribosomes are structurally different from prokaryotic ribosomes.

Question 15

What is the default transcriptional state of genes under positive control in bacterial operons?

Accepted Answer

Transcription is off unless activated by an activator protein.

Question 16

Which molecule acts as an inducer in the lac operon, inactivating the repressor protein?

Accepted Answer

Allolactose

Question 17

What is diauxic growth in bacteria?

Accepted Answer

Growth in the presence of two carbon sources, with sequential utilization and a lag phase between.

Question 18

Which type of mutation results in a frameshift in the open reading frame?

Accepted Answer

Insertion or deletion of nucleotides not in multiples of three

Question 19

What is the effect of a nonsense mutation in a coding region?

Accepted Answer

It changes a codon to a stop codon, terminating translation prematurely.

Question 20

Which equation correctly represents the formation of a phosphodiester bond between two nucleotides?

Accepted Answer

$$	ext{Nucleotide}_1 + 	ext{Nucleotide}_2 ightarrow 	ext{Nucleotide}_1	ext{-}O	ext{-}P	ext{-}O	ext{-}	ext{Nucleotide}_2 + H_2O$$

Microbiology Exam 2 Study Guide: Genetics, DNA Structure, Central Dogma, Operons, and Mutations

Study Guide - Practice Questions