Chapter 8 Microbiology

A gene is best defined as
A sequence of nucleotides in DNA that codes for a functional product.
A sequence of nucleotides in RNA that codes for a functional product.
A transcribed unit of DNA.
Three nucleotides that code for an amino acid.
A segment of DNA.

A sequence of nucleotides in DNA that codes for a functional product.

Which of the following pairs is mismatched?
RNA polymerase – makes a molecule of RNA from an RNA template
DNA polymerase – makes a molecule of DNA from a DNA template
DNA ligase – joins segments of DNA
Transposase – insertion of DNA segments into DNA
DNA gyrase – coils and twists DNA

RNA polymerase – makes a molecule of RNA from an RNA template

Which of the following statements is false?
The leading strand of DNA is made continuously.
The lagging strand of DNA is started by an RNA primer.
DNA polymerase joins nucleotides in one direction only.
Multiple replication forks are possible on a bacterial chromosome.
DNA replication proceeds in one direction around the bacterial chromosome.

DNA replication proceeds in one direction around the bacterial chromosome.

DNA is constructed of
Two strands of identical nucleotides with hydrogen bonds between them.
Two strands of nucleotides running antiparallel.
A single strand of nucleotides with internal hydrogen bonding.
Nucleotides bonded A-C and G-T.
None of the above.

Two strands of nucleotides running antiparallel.

Which of the following is NOT a product of transcription?
A new strand of DNA
rRNA
tRNA
mRNA
None of the above

A new strand of DNA

Which of the following statements about bacteriocins is false?
They cause food-poisoning symptoms.
They can be used to identify certain bacteria.
Bacteriocins kill baceria.
The genes coding for them are on plasmids.
Nisin is a bacteriocin used as a food preservative.

They cause food-poisoning symptoms.

In the figure, which colonies are streptomycin-resistant and leucine-requiring?
1, 2, 3, and 9
4, 6, and 8
3 and 9
5 and 6
4 and 8

4 and 8

Culture 1: F+, leucine+, histidine+
Culture 2: F-, leucine-, histidine-

In the table above, what will be the result of conjugation between cultures 1 and 2?
1 will become F-, leu+, his+;
2 will become F+, leu-, his-
1 will remain the same;
2 will become F+, leucine-, histidine-
1 will become F-, leu-, his-;
2 will remain the same
1 will remain the same;
2 will become F+, leu+, his+
1 will remain the same;
2 will become F+ and recombination may occur

1 will remain the same; 2 will become F+, leucine-, histidine-

Culture 1: F+, leucine+, histidine+
Culture 2: F-, leucine-, histidine-

In the table above, if culture 1 mutates to Hfr, what will be the result of conjugation between the two cultures?
They will both remain the same
1 will remain the same;
Recombination will occur in 2
1 will become F+, leu+, his+;
2 will become F+, leu+, his+
1 will become F-, leu+, his+;
2 will become Hfr, leu+, his+
Can’t tell

1 will remain the same; Recombination will occur in 2

An enzyme produced in response to the presence of a substrate is called
A restriction enzyme.
A repressible enzyme.
An operator.
A promoter.
An inducible enzyme.

An inducible enzyme.

Transformation is the transfer of DNA from a donor to a recipient cell
By cell-to-cell contact.
As naked DNA in solution.
By sexual reproduction.
By crossing over.
By a bacteriophage.

As naked DNA in solution.

Genetic change in bacteria can be brought about by
Conjugation.
Transduction.
Mutation.
Transformation.
All of the above.

All of the above.

Which of the following statements is false regarding a bacterium that is R+?
R+ can be transferred to a different species.
It is resistant to certain drugs and heavy metals.
It possesses a plasmid.
R+ can be transferred to a cell of the same species.
It is F+.

It is F+.

The initial effect of ionizing radiation on a cell is that it causes
The cells to get hot.
DNA to break.
The formation of highly reactive ions.
Bonding between adjacent thymines.
Base substitutions.

The formation of highly reactive ions.

According to the operon model, for the synthesis of an inducible enzyme to occur, the
Substrate must bind to the enzyme.
Repressor must bind to the operator.
Repressor must not be synthesized.
End-product must not be in excess.
Substrate must bind to the repressor.

Substrate must bind to the repressor.

Synthesis of a repressible enzyme is stopped by
The end-product binding to the promoter.
The corepressor binding to the operator.
The allosteric transition.
The substrate binding to the repressor.
The corepressor-repressor binding to the operator.

The corepressor-repressor binding to the operator.

In the figure, if base 4 is thymine, what is base 4′?
Uracil
Guanine
Cytosine
Thymine
Adenine

Adenine

In the figure, if base 4 is thymine, what is base 11′?
Uracil
Thymine
Cytosine
Guanine
Adenine

Thymine

In the figure, base 2 is attached to
Phosphate.
Deoxyribose.
Ribose.
Thymine.
Can’t tell.

Deoxyribose.

The damage caused by ultraviolet radiation is
Repaired during translation.
Repaired during transcription.
Never repaired.
Repaired by DNA replication.
Cut out and replaced.

Cut out and replaced.

If the sequence of amino acids encoded by a strand of DNA is serine-alanine-lysine-leucine, what is the order of bases in the template strand of DNA?
3′ UGUGCAAAGUUA
3′ TCTCGTTTGTTA
3′ AGACGTTTCAAT
5′ TGTGCTTTCTTA
5′ AGAGCTTTGAAT

3′ AGACGTTTCAAT

If the sequence of amino acids encoded by a strand of DNA is serine-alanine-lysine-leucine, the coding for the antisense strand of DNA is
3′ TCACGUUUCAAU
5′ ACAGTTTCAAT
3′ UCUCGAAAGUUA
3′ UGUGCAAAGUUA
5′ TCTGCAAAGTTA

5′ TCTGCAAAGTTA

The anticodon for valine is
GUU
CAA
CUU
GTA
CTT

CAA

What is the sequence of amino acids encoded by the following sequence of bases in a strand of DNA?

3′ ATTACGCTTTGC

Transcription would stop at the first codon
Asparagine-arginine-lysine-alanine
Asparagine-cysteine-valine-serine
Leucine-arginine-lysine-alanine
Can’t tell

Transcription would stop at the first codon

If a frameshift mutation occurred in the sequence of bases shown below, what would be the sequence of amino acids coded for?

3′ ATTACGCTTTGC
Asparagine-cysteine-valine-serine
Leucine-arginine-lysine-alanine
Asparagine-arginine-lysine-alanine
Translation would stop at the first codon
Can’t tell

Can’t tell

In the figure, if compound C reacts with the allosteric site of enzyme A, this would exemplify
Transcription.
Feedback inhibition.
Competitive inhibition.
A mutation.
Repression.

Feedback inhibition.

In the figure, if enzyme A is a repressible enzyme, compound C would
Bind to the enzyme.
Bind to the corepressor.
Bind to RNA polymerase.
Bind to gene a.
Always be in excess.

Bind to the corepressor

In the figure, if enzyme A is an inducible enzyme,
Compound C would react with gene a.
Compound C would bind to the repressor.
Compound A would react with enzyme B.
Compound A would bind to the repressor.
Compound B would bind to enzyme A.

Compound A would bind to the repressor.

Conjugation differs from reproduction because conjugation
Transcribes DNA to RNA.
Copies RNA to make DNA.
Transfers DNA vertically, to new cells.
Replicates DNA.
Transfers DNA horizontally, to cells in the same generation.

Transfers DNA horizontally, to cells in the same generation.

The necessary ingredients for DNA synthesis can be mixed together in a test tube. The DNA polymerase is from Thermus aquaticus, and the template is from a human cell. The DNA synthesized would be most similar to
T. aquaticus DNA.
Human DNA.
A mixture of human and T. aquaticus DNA.
T. aquaticus RNA.
Human RNA.

Human DNA.

Based on the information in the table, prostate cancer is probably the result of which kind of mutation?
Missense
Analog
Nonsense
Frameshift
None of the above

Nonsense

In the figure, the antibiotic chloramphenicol binds the 50S ribosome as shown. From this information you can conclude that chloramphenicol
Prevents translation in eukaryotes.
Prevents transcription in eukaryotes.
Prevents transcription in prokaryotes.
Prevents translation in prokaryotes.
Prevents mRNA-ribosome binding.

Prevents translation in prokaryotes.

The mechanism by which the presence of glucose inhibits the arabinose operon is
Repression.
Induction.
DNA polymerase.
Catabolite repression.
Translation.

Catabolite repression.

The mechanism by which the presence of arabinose controls the arabinose operon is
Induction.
Repression.
DNA polymerase.
Translation.
Catabolite repression.

Induction.

If you knew the sequence of nucleotides within a gene, which one of the following could you determine with the most accuracy?
The primary structure of the protein
The tertiary structure of the protein
The quaternary structure of the protein
The secondary structure of the protein
Can’t tell

The primary structure of the protein

An enzyme that makes covalent bonds between nucleotide sequences in DNA is
DNA polymerase.
Transposase.
Restriction enzyme.
DNA ligase.
RNA polymerase.

DNA ligase.

An enzyme that copies DNA to make a molecule of RNA is
RNA polymerase.
Restriction enzyme.
DNA polymerase.
Transposase.
DNA ligase.

RNA polymerase.

An enzyme that cuts double-stranded DNA at specific nucleotide sequences.
DNA ligase
Transposase
DNA polymerase
Restriction enzyme
RNA polymerase

Restriction enzyme

Repair of damaged DNA might be viewed as a race between an endonuclease and
DNA polymerase.
Methylase.
Helicase.
DNA ligase.
Primase.

Methylase.

The cancer gene ras produces mRNA containing an extra exon that includes a number of UAA codons. Cancer cells produce ras mRNA missing this exon. This mistake most likely is due to a mistake by
UV radiation.
DNA polymerase.
snRNPs.
A chemical mutagen.
Photolyases.

snRNPs.

In the figure, which model of the lac operon correctly shows RNA polymerase, lactose, and repressor protein when the structural genes are being transcribed?
a
b
c
d
e

d

In transcription,
DNA is changed to RNA.
DNA is copied to RNA.
RNA is copied to DNA.
DNA is replicated.
Proteins are made.

DNA is copied to RNA.

Assume the two E.coli strains shown below are allowed to conjugate.
Hfr: pro+, arg+, his+, lys+, met+, ampicillin-sensitive
F: pro-, arg-, his-, lys-, met-, ampicillin-resistant
What supplements would you add to glucose minimal salts agar to select for a recombinant cell that is lys+, arg+, amp-resistant?
Proline, histidine, methionine
Lysine, arginine
Ampicillin, lysine, arginine
Ampicillin, proline, histidine, methionine
Ampicillin, proline, histidine, lysine

Ampicillin, proline, histidine, methionine

Protein synthesis in eukaryotes is similar to the process in prokaryotes in that both eukaryotes and prokaryotes
Have introns.
Use codons to arrange amino acids.
Use methionine as the start amino acid.
Require snRNPS.
Have exons.

Use codons to arrange amino acids.