Test Bank Chapter 11 Mechanisms Of Microbial Genetics

Chapter 11: Mechanisms of Microbial Genetics

= Correct answer

Multiple Choice

1. Gene expression includes which of the following?

A. DNA replication
B. replication, transcription, and translation

C. transcription and translation

D. translation only

Difficulty: Easy

ASM Standard: N/A

1. The central dogma describes which of the following?
   A. the process by which enzymes are modified after translation

B. the steps of gene expression
C. the way DNA is replicated

D. the way RNA is used as a template to make DNA

Difficulty: Easy

ASM Standard: N/A

1. During bacterial DNA replication, which of the following holds open the replication bubble?

A. DNA polymerases

B. helicases

C. primers

D. single-strand binding proteins

Difficulty: Easy

ASM Standard: N/A

1. Telomeres found in which of the following?

A. all microbes

B. animal cells only, not in unicellular organisms
C. fungal, protist, plant, and animal chromosomes

D. microbes only, including all domains

Difficulty: Easy

ASM Standard: 16

1. Which of the following best describes the direction in which lagging strands are added?

A. as 5′ to 3′ Okazaki fragments in an overall 3′ to 5′ direction only

B. as 5′ to 3′ Okazaki fragments in an overall 5′ to 3′ direction only

C. in the 3′ to 5′ or 5′ to 3′ direction

D. in variable directions depending on the species

Difficulty: Easy

ASM Standard: N/A

1. Which of the following correctly describes uracil and where is it found?

A. It is a nitrogenous base found in DNA and RNA.
B. It is a nitrogenous base found in DNA only.

C. It is a nitrogenous base found in RNA only.

D. It is a nitrogenous base found only in nucleotides of molecules other than RNA and DNA.

Difficulty: Easy

ASM Standard: N/A

1. Which of the following is another name for the template strand (the strand of DNA that is transcribed)?

A. anticodon strand

B. antisense strand
C. sense strand

D. transcription strand

Difficulty: Moderate

ASM Standard: N/A

1. Which of the following correctly describes events that occur during transcription?

A. DNA polymerase binds to the site of initiation.
B. RNA polymerase binds to the core enzyme.
C. RNA polymerase binds to the operator.

D. RNA polymerase binds to the promoter.

Difficulty: Easy

ASM Standard: N/A

1. Which of the following correctly explains why DNA replication is described as semiconservative?

A. Each daughter strand contains one old strand and one new strand.

B. Each daughter strand contains two new strands.

C. The nucleotides used in replication are recycled multiple times.

D. The nucleotides used in replication contain old and new components.

Difficulty: Moderate

ASM Standard: N/A

1. During DNA replication in bacteria, which of the following enzymes adds DNA nucleotides to the growing strand?

A. DNA polymerase I

B. DNA polymerase II

C. DNA polymerase III

D. DNA polymerase IV

Difficulty: Moderate

ASM Standard: 16

1. Topoisomerase II in bacteria is also called which of the following?

A. gyrase

B. helicase

C. primase

D. topoisomerase β

Difficulty: Moderate

ASM Standard: 16

1. DNA polymerase III adds DNA nucleotides in which of the following direction(s)?

A. in the 3′ to 5′ direction only
B. in the 3′ to 5′ direction and in 5′ to 3′ direction

C. in the 5′ to 3′ direction on one strand and in the 3′ to 5′ direction on the complementary strand
D. in the 5′ to 3′ direction only

Difficulty: Moderate

ASM Standard: 16

1. Which of the following removes the primers during DNA replication in bacteria?

A. DNA polymerase I

B. DNA polymerase II

C. DNA polymerase III

D. DNA polymerase IV

Difficulty: Moderate

ASM Standard: 16

1. The noncoding, repetitive sequences at the end of eukaryotic chromosomes are called which of the following?

A. bubbles

B. forks

C. lagging strands

D. telomeres

Difficulty: Easy

ASM Standard: 16

1. During DNA replication, the lagging strand is formed from which of the following?

A. helicases

B. leading strands

C. Okazaki fragments

D. single strand binding proteins

Difficulty: Moderate

ASM Standard: N/A

1. Which of the following is the maximal rate of growth of a new bacterial DNA strand?

A. 10 nucleotides per second

B. 100 nucleotides per second

C. 1000 nucleotides per second

D. 10,000 nucleotides per second

Difficulty: Moderate

ASM Standard: N/A

1. Which statement best describes DNA polymerase I?

A. It acts as a ligase.
B. It has exonuclease activity.

C. It joins fragments together.

D. It prevents supercoiling.

Difficulty: Moderate

ASM Standard: 16

1. Which describes one difference between prokaryotic and eukaryotic DNA replication?

A. Eukaryotes have more origins of replication than prokaryotes.

B. The chromosomes are usually circular in eukaryotes and usually linear in prokaryotes.

C. The DNA is not tightly complexed with histones in eukaryotes.

D. The RNA primer is removed by ribonuclease H instead of a DNA polymerase I in prokaryotes

Difficulty: Moderate

ASM Standard: 16

1. Telomerase in humans is generally active in which cells?

A. all cells

B. all cells during childhood, but not during adulthood

C. in stem cells and germ cells

D. stem cells only

Difficulty: Moderate

ASM Standard: N/A

1. Which of the following uses rolling circle replication?

A. some bacteria only

B. some bacteria and some viruses

C. some bacteria, some plasmids, and some viruses
D. some bacteria, some plasmids, some viruses, and some eukaryotic main chromosomes

Difficulty: Moderate

ASM Standard: 16

1. Which of the following defines a sigma (σ) factor?

A. a subunit of eukaryotic RNA polymerase that is important in binding to DNA
B. a subunit of eukaryotic RNA polymerase that is important in binding to RNA

B. a subunit of prokaryotic RNA polymerase that is important in binding to DNA

C. a subunit of prokaryotic RNA polymerase that is important in binding to RNA

Difficulty: Easy

ASM Standard: 16

1. Which sequences of eukaryotic genes code for proteins?

A. exons

B. introns
C. invariant

D. the spliceosome

Difficulty: Moderate

ASM Standard: 16

1. Which of the following is one important distinction between prokaryotic and eukaryotic mRNA?

A. Eukaryotic mRNA is generally monocistronic.
B. Eukaryotic mRNA is generally polycistronic.

C. Eukaryotic mRNA is equally likely to be monocistronic or polycistronic.

D. Eukaryotic mRNA is often both monocistronic and polycistronic within an operon.

Difficulty: Moderate

ASM Standard: 16

1. Stop codons are also known as which of the following?

A. antisense codons
B. missense codons

C. nonsense codons

D. sense codons

Difficulty: Moderate

ASM Standard: N/A

1. Which researchers provided evidence that DNA replication was semiconservative?

A. George Beadle, Edward Tatum, and colleagues

B. Alfred Hershey and Martha Chase

C. Matthew Meselson and Franklin Stahl

D. James Watson and Francis Crick

Difficulty: Moderate

ASM Standard: N/A

1. Quinolones are medications that target which of the following?

A. DNA gyrase and topoisomerase IV

B. ligase and topoisomerase III
C. primase and topoisomerase I

D. replicase and topoisomerase V

Difficulty: Difficult

ASM Standard: 14

1. Following DNA replication, bacterial chromosomes become which of the following?

A. concatenated
B. linear

C. plasmids

D. single stranded

Difficulty: Difficult

ASM Standard: 16

1. Human telomeres contain 100 to 1000 copies of which nucleotide sequence?

A. AATAT

B. TATATA

C. TTAGGG

D. TTTTTT

Difficulty: Difficult

ASM Standard: N/A

1. Which enzyme(s) elongate the lagging strand during replication in eukaryotes?

A. DNA polymerases I and III

B. DNA polymerase III

C. DNA polymerase δ

D. DNA polymerase ε

Difficulty: Difficult

ASM Standard: 16

1. What does the σ factor recognize?

A. the –10 consensus sequence in eukaryotes
B. the –10 consensus sequence in prokaryotes

C. the –35 consensus sequence in prokaryotes

D. the TATA box in eukaryotes

Difficulty: Difficult

ASM Standard: 16

1. Which of the following is the function of the σ factor?

A. It allows DNA polymerase to recognize a specific promoter in eukaryotes.

B. It allows RNA polymerase to bind to a specific promoter in eukaryotes.

C. It allows RNA polymerase to recognize a specific promoter in prokaryotes.

D. It allows RNA polymerase to terminate transcription in prokaryotes.

Difficulty: Difficult

ASM Standard: 16

1. Which statement best describes selenocysteine and pyrrolysine?

A. They are amino acids commonly found in eukaryotic proteins.

B. They are amino acids commonly found in proteins in all microbes.

C. They are unusual amino acids found in some archaea.

D. They are unusual amino acids found in some bacteria and archaea.

Difficulty: Difficult

ASM Standard: 16

1. Which statement best describes polyribosomes?

A. They are only found in archaea.

B. They can occur in archaea, bacteria, and eukaryotes during transcription.

C. They can only form after RNA has left the nucleus in eukaryotes, but are found in all domains.

D. They can only form in eukaryotes, not in other organisms, and can only form once the RNA has been fully processed.

Difficulty: Difficult

ASM Standard: 16

1. Which amino acid is attached to a tRNA?

A. aminoacyl tRNA synthetase

B. an activated amino acid

C. a charged amino acid

D. a cognate amino acid

Difficulty: Difficult

ASM Standard: N/A

True/False

1. A particular genotype always produces the same phenotype.

Difficulty: Moderate

ASM Standard: N/A

1. Prokaryotes usually have a single origin of replication, whereas eukaryotes usually have multiple origins of replication.

Difficulty: Easy

ASM Standard: 16

1. Archaea, Bacteria, and Eukarya use different DNA polymerases.

Difficulty: Moderate
ASM Standard: 16

1. RNA primases require a free 3′-OH group to add nucleotides to a growing strand.

Difficulty: Moderate

ASM Standard: N/A

1. The termination of DNA replication is understood far better than the initiation of DNA replication.

Difficulty: Moderate

ASM Standard: N/A

1. At 100 nucleotides per second, replication of eukaryotic DNA is faster than replication of prokaryotic DNA.

Difficulty: Moderate

ASM Standard: 16

1. Prokaryotic RNA transcripts undergo splicing.

Difficulty: Difficult

ASM Standard: 16

1. Matthew Meselson and Franklin Stahl used radiolabeled phosphorus to determine that DNA replication is semiconservative.

Difficulty: Difficult

ASM Standard: N/A

Matching

1. Match each molecule with its function.

Answers: A. ii., B. iii., C. i.

Difficulty: Easy

ASM Standard: N/A

1. Match each molecule with its role in prokaryotic DNA replication.

Answers: A. iv., B. v., C. iii., D. i., E. ii.

Difficulty: Moderate

ASM Standard: 16

1. Match the enzyme with its role in prokaryotic DNA replication.

Answers: A. ii., B. iii., C. i., D. iv.

Difficulty: Moderate

ASM Standard: 16

1. Match the process that contributes to prokaryotic genetic diversity with the best description.

Answers: A. i., B. iii., C. ii., D. iv.

Difficulty: Moderate

ASM Standard: 2

1. Match each part of the operon with its best description.

Answers: A. ii., B. i., C. iii.

Difficulty: Easy

ASM Standard: 17

1. Match each mutagen with its effect on DNA.

Answers: A. iv., B. iii., C. ii., D. i.

Difficulty: Difficult

ASM Standard: 2

Fill in the Blank

1. ________ expression occurs when genes are continuously expressed.

Difficulty: Easy

ASM Standard: 17

1. The structure formed by an mRNA with multiple attached ribosomes is called a(n) ________.

Difficulty: Easy

ASM Standard: 16

1. ________ mRNA codes for multiple polypeptides.

Difficulty: Moderate

ASM Standard: N/A

1. The ________ subunit of prokaryotic RNA polymerase helps it bind to the –35 consensus sequence.

Difficulty: Moderate

ASM Standard: 16

1. ________ are transcription factors that can bind to the regulatory region of an operon to increase transcription levels above basal levels.

Difficulty: Moderate

ASM Standard: 17

1. The tryptophan operon is turned off when there is an excess of tryptophan, making it a(n) ________ operon.

Difficulty: Moderate

ASM Standard: 17

1. When lactose is present but there is no ________, the CAP–cAMP complex binds to the regulatory region of the lac operon.

Difficulty: Moderate

ASM Standard: 17

1. ________ are nucleotide derivatives that change gene expression in response to stress and are especially important in pathogenic bacteria.

Difficulty: Moderate

ASM Standard: 23

1. A molecule that influences regulation of prokaryotic gene expression found in the 5′ end of mRNA is called a(n) ________.

Difficulty: Difficult

ASM Standard: 17

1. The trp operon in Escherichia coli can be regulated by the type of stem loop structures formed, which is a type of regulation called ________?

Difficulty: Difficult

ASM Standard: 17

Short Answer

1. What is the term for horizontal gene transmission by a virus?

Sample

Difficulty: Easy

ASM Standard: 2

1. What is a riboswitch?

Sample

Difficulty: Easy

ASM Standard: 17

1. What is the term for the process by which mRNA is used to make a protein?

Sample

Difficulty: Easy

ASM Standard: N/A

1. What is another term for the genetic elements often called “jumping genes?”

Sample

Difficulty: Easy

ASM Standard: 2

1. Why is a primase required for DNA replication, instead of just using DNA polymerase?

Sample

Difficulty: Moderate

ASM Standard: 23, 24

1. Will the structural genes of the lac operon be expressed when there is plenty of lactose and glucose? Will the repressor be bound to the operator? Why or why not?

Sample

Difficulty: Moderate

ASM Standard: 17

1. What is epigenetic regulation?

Sample

Difficulty: Moderate

ASM Standard: 17

1. Explain what a frameshift mutation is and why frameshift mutations often have severe consequences.

Sample

Difficulty: Moderate

ASM Standard: 2

1. What can cause a thymine dimer and what are the consequences of one forming?

Sample

Difficulty: Moderate

ASM Standard: 2

1. How does horizontal gene transfer differ from vertical gene transfer?

Sample

Difficulty: Moderate

ASM Standard: 2

1. Why is the error rate for bacterial DNA replication very low?

Sample

Difficulty: Moderate

ASM Standard: 2

1. How many of the 64 codons are stop codons?

Sample

Difficulty: Moderate

ASM Standard: N/A

1. What does it mean to say that the genetic code is degenerate?

Sample

Difficulty: Difficult

ASM Standard: N/A

1. In eukaryotes, RNA produced by transcription is not immediately ready for translation. What steps have to take place before translation can occur?

Sample

Difficulty: Difficult

ASM Standard: 16

1. What chemical reaction is catalyzed by DNA ligase?

Sample

Difficulty: Difficult

ASM Standard: N/A

Brief Essay

Essay Question Rubric

Assume rating/grading scale for the question ranges from 0 to 3 points.

1. Describe one way in which a transposon could cause a mutation. Be sure also to explain how transposons work.

Difficulty: Moderate

ASM Standard: 2

1. A transposon inserts structural genes (the genes that code for proteins) into the lac operon. What would happen if the bacterium were inoculated onto medium containing lactose? Explain what would happen by describing how each part of the operon would be affected (i.e., whether it would or would not be affected) and then whether the bacterium would metabolize lactose.

Difficulty: Moderate

ASM Standard: 2

1. Ethidium bromide is commonly used to stain DNA on electrophoresis gels. However, ethidium bromide is a mutagen. Explain how ethidium bromide causes mutations in DNA.

Difficulty: Moderate

ASM Standard: 2

1. Why is it necessary to have a control group when you use an Ames test?

Difficulty: Moderate

ASM Standard: 2

1. Explain the major differences in gene expression between prokaryotes and eukaryotes. Include at least three differences.

Difficulty: Difficult

ASM Standard: 16

1. Mutations may be harmful but may also be beneficial or neutral. Explain some examples of neutral and beneficial mutations.

Difficulty: Difficult

ASM Standard: 2, 23

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