Deck 8: Microbial Genetics

Question 1

Table 8.2 $$\begin{array}{l}\underline{\text { Codon on mRNA and corresponding amino acid} }\\\begin{array} { l l l l } \text { UUA } & \text { leucine } & \text { UAA } & \text { nonsense } \\\text { GCA } & \text { alanine } & \text { AAU } & \text { sparagine } \\\text { AAG } & \text { lysine } & \text { UGC } & \text { cysteine } \\\text { GUU } & \text { valine } & \text { UCG, UCU } & \text { serine }\end{array}\end{array}$$

-(Use Table 8.2.) The anticodon for valine is

A) GTA
B) CTT
C) CUU
D) GUU
E) CAA

Answer 1

CAA

Question 2

Synthesis of a repressible enzyme is stopped by

A) The substrate binding to the repressor.
B) The end- product binding to the promoter.
C) The corepressor binding to the operator.
D) The corepressor- repressor binding to the operator.
E) The allosteric transition.

Answer 2

D

Question 3

Table 8.2 $$\begin{array}{l}\underline{\text { Codon on mRNA and corresponding amino acid }}\\\begin{array} { l l l l } \text { UUA } & \text { leucine } & \text { UAA } & \text { nonsense } \\\text { GCA } & \text { alanine } & \text { AAU } & \text { sparagine } \\\text { AAG } & \text { lysine } & \text { UGC } & \text { cysteine } \\\text { GUU } & \text { valine } & \text { UCG, UCU } & \text { serine }\end{array}\end{array}$$

-In transcription,

A) Proteins are made.
B) RNA is copied to DNA.
C) DNA is changed to RNA.
D) DNA is copied to RNA.
E) DNA is replicated.

Answer 3

DNA is copied to RNA.

Question 4

All of the following are true about bacteriocins except

A) Nisin is a bacteriocin used as a food preservative.
B) The genes coding for them are on plasmids.
C) Bacteria that produce bacteriocins are resistant to their own bacteriocins.
D) They cause food poisoning symptoms.
E) None of the above.

Question 5

The initial effect of ionizing radiation on a cell is that it causes

A) DNA to break.
B) The formation of highly reactive ions.
C) Base substitutions.
D) Bonding between adjacent thymines.
E) The cells to get hot.

Question 6

An enzyme that covalently bonds nucleotide sequences in DNA is

A) DNA polymerase.
B) DNA ligase.
C) RNA polymerase.
D) Transposase.
E) Restriction enzyme.

Question 7

Table 8.2 $\text { Codon on mRNA and corresponding amino acid }$
$\begin{array}{llll}\text { UUA } & \text { leucine } & \text { UAA } & \text { nonsense } \\\text { GCA } & \text { alanine } & \text { AAU } & \text { sparagine } \\\text { AAG } & \text { lysine } & \text { UGC } & \text { cysteine }\\\text { GUU} & \text { valine }&\text { UCG, UCU } & \text {serine }\end{array}$

-(Use Table 8.2.) If the sequence of amino acids coded for by a strand of DNA is serine- alanine- lysine- leucine, the coding for the antisense strand of DNA is

A) 5' TCTGCAAAGTTA
B) 3' TCACGUUUCAAU
C) 3' UGUGCAAAGUUA
D) 5' ACAGTTTCAAT
E) 3' UCUCGAAAGUUA

Question 8

In Figure 8.2, if base 4 is thymine, what is base 11'?

A) Thymine
B) Adenine
C) Guanine
D) Cytosine
E) Uracil

Question 9

An enzyme that copies DNA to make a molecule of RNA is

A) Transposase.
B) RNA polymerase.
C) Restriction enzyme.
D) DNA ligase.
E) DNA polymerase.

Question 10

A cell that cannot make tRNA

A) Can make proteins if amino acids are provided in the growth medium.
B) Can't make proteins unless aminoacyl synthetase is provided in the growth medium.
C) Can make proteins if mRNA is provided in the growth medium.
D) Can't make proteins.
E) None of the above.

Question 11

Table 8.1
$\text { Culture } 1: \mathrm{F}^{+} \text {, leucine }{ }^{+} \text {, histidine }{ }^{+}$
$\text { Culture 2: } \mathrm{F}^{-} \text {, leucine-, histidine- }$

-In Table 8.1, if culture 1 mutates to Hfr, what will be the result of conjugation between the two cultures?

A) They will both remain the same
B) 1 will become F- , leu+, his+;
2 will become Hfr, leu+, his+

C) 1 will become F+, leu+, his+;
2 will become F+, leu+, his+

D) 1 will remain the same;
Recombination will occur in 2

E) Can't tell

Question 12

Which of the following is not a product of transcription?

A) mRNA
B) A new strand of DNA
C) tRNA
D) rRNA
E) None of the above

Question 13

The mechanism by which the presence of glucose inhibits the arabinose operon.

A) DNA polymerase
B) Repression
C) Induction
D) Catabolic repression
E) Translation

Question 14

Table 8.2 $$\begin{array}{l}\underline{\text { Codon on mRNA and corresponding amino acid }}\\\begin{array} { l l l l } \text { UUA } & \text { leucine } & \text { UAA } & \text { nonsense } \\\text { GCA } & \text { alanine } & \text { AAU } & \text { sparagine } \\\text { AAG } & \text { lysine } & \text { UGC } & \text { cysteine } \\\text { GUU } & \text { valine } & \text { UCG, UCU } & \text { serine }\end{array}\end{array}$$

-An antibiotic that binds the 50S portion of the ribosome as shown above would

A) Prevent peptide bond formation.
B) Prevent tRNA attachment.
C) Prevent transcription.
D) Stop the ribosome from moving along the mRNA.
E) None of the above.

Question 15

Which of the following proteins are not coded for by genes carried on plasmids?

A) Enzymes that catabolize hydrocarbons
B) Enzymes that inactivate antibiotics
C) Enzymes necessary for conjugation
D) Bacteriocins
E) None of the above

Question 16

Conjugation differs from reproduction because conjugation

A) Replicates DNA.
B) Transcribes DNA to RNA.
C) Transfers DNA horizontally, to cells in the same generation.
D) Transfers DNA vertically, to new cells.
E) None of the above.

Question 17

Table 8.1
$\text { Culture } 1: \mathrm{F}^{+} \text {, leucine }{ }^{+} \text {, histidine }{ }^{+}$
$\text { Culture 2: } \mathrm{F}^{-} \text {, leucine-, histidine- }$

-In Table 8.1, what will be the result of conjugation between cultures 1 and 2?

A) 1 will become F- , leu- , his- ;
2 will remain the same

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

C) 1 will become F- , leu+, his+;
2 will become F+, leu- , his-

D) 1 will remain the same;
2 will become F+ and recombination may occur

E) 1 will remain the same;
2 will become F+, leu+, his+

Question 18

Table 8.2 $$\begin{array}{l}\underline{\text { Codon on mRNA and corresponding amino acid }}\\\begin{array} { l l l l } \text { UUA } & \text { leucine } & \text { UAA } & \text { nonsense } \\\text { GCA } & \text { alanine } & \text { AAU } & \text { sparagine } \\\text { AAG } & \text { lysine } & \text { UGC } & \text { cysteine } \\\text { GUU } & \text { valine } & \text { UCG, UCU } & \text { serine }\end{array}\end{array}$$

-(Use Table 8.2.) If a frameshift mutation occurred in a sequence of bases shown below, what would be the sequence of amino acids coded for?
3' ATTACGCTTTGC

A) Asparagine- cysteine- valine- serine
B) Leucine- arginine- lysine- alanine
C) Asparagine- arginine- lysine- alanine
D) Translation would stop at the first codon
E) Can't tell

Question 19

Table 8.3 - Metabolic Pathway
$\begin{array}{cc}\text { Gene } a & \text { Gene } b \\? &? \\\text { Enzyme A } & \text { Enzyme B } \\? & ?\end{array}$
$\text { Compound A ?Compound B? Compound C }$

-In Table 8.3, if compound C reacts with the allosteric site of enzyme A, this would exemplify

A) Competitive inhibition.
B) Feedback inhibition.
C) End- product repression.
D) A mutation.
E) None of the above.

Question 20

Table 8.2 $$\begin{array}{l}\underline{\text { Codon on mRNA and corresponding amino acid }}\\\begin{array} { l l l l } \text { UUA } & \text { leucine } & \text { UAA } & \text { nonsense } \\\text { GCA } & \text { alanine } & \text { AAU } & \text { sparagine } \\\text { AAG } & \text { lysine } & \text { UGC } & \text { cysteine } \\\text { GUU } & \text { valine } & \text { UCG, UCU } & \text { serine }\end{array}\end{array}$$

-(Use Table 8.2.) What is the sequence of amino acids coded for by the following sequence of bases in a strand of DNA?
3' ATTACGCTTTGC

A) Asparagine- cysteine- valine- serine
B) Asparagine- arginine- lysine- alanine
C) Leucine- arginine- lysine- alanine
D) Transcription would stop at the first codon
E) Can't tell

Question 21

The damage caused by ultraviolet radiation is

A) Never repaired.
B) Repaired by DNA replication.
C) Repaired during translation.
D) Cut out and replaced.
E) Repaired during transcription.

Question 22

The mechanism by which the presence of arabinose controls the arabinose operon.

A) DNA polymerase
B) Catabolic repression
C) Induction
D) Repression
E) Translation

Question 23

The lac operon

A) Produces repressible enzymes.
B) Produces inducible enzymes.
C) Produces constitutive enzymes.
D) Hydrolyzes lactose.
E) None of the above.

Question 24

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

A) T. aquaticus DNA.
B) A mixture of human and T. aquaticus DNA.
C) Human RNA.
D) T. aquaticus RNA.
E) Human DNA.

Question 25

Which of the following is not true of a bacterium that is R+?

A) It is resistant to certain drugs and heavy metals.
B) R+ can be transferred to a recipient cell.
C) It is F+.
D) R+ refers to the possession of a plasmid.
E) None of the above.

Question 26

DNA is constructed of

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

Question 27

Figure 8.2

In Figure 8.2, if base 4 is thymine, what is base 4'?

A) Adenine
B) Uracil
C) Cytosine
D) Thymine
E) Guanine

Question 28

If you knew the sequence of nucleotides within a gene, which one of the following could you determine with the most accuracy?

A) The tertiary structure of the protein
B) The quaternary structure of the protein
C) The secondary structure of the protein
D) The primary structure of the protein
E) Can't tell

Question 29

An enzyme produced in response to the presence of a substrate is called

A) A repressible enzyme.
B) An inducible enzyme.
C) An operator.
D) A promoter.
E) A restriction enzyme.

Question 30

Table 8.3 - Metabolic Pathway
$\begin{array}{cc}\text { Gene } a & \text { Gene } b \\? & ? \\\text { Enzyme A } & \text { Enzyme B } \\?& ?\end{array}$
$\text { Compound A ? Compound B ?Compound C }$

-In Table 8.3, if enzyme A is a repressible enzyme, compound C would

A) Always be in excess.
B) Bind to the corepressor.
C) Bind to the enzyme.
D) All of the above.
E) None of the above.

Question 31

Transformation is the transfer of DNA from a donor to a recipient cell

A) By a bacteriophage.
B) By sexual reproduction.
C) As naked DNA in solution.
D) By cell- to- cell contact.
E) By crossing over.

Question 32

According to the operon model, for the synthesis of an inducible enzyme to occur, the

A) Substrate must bind to the repressor.
B) End- product must not be in excess.
C) Repressor must not be synthesized.
D) Repressor must bind to the operator.
E) Substrate must bind to the enzyme.

Question 33

Which of the following pairs is mismatched?

A) RNA polymerase - makes a molecule of RNA from an RNA template
B) DNA ligase - joins segments of DNA
C) DNA gyrase - coils and twists DNA
D) Transposase - insertion of DNA segments into DNA
E) DNA polymerase - makes a molecule of DNA from a DNA template

Question 34

An enzyme that cuts double- stranded DNA at specific nucleotide sequences.

A) RNA polymerase
B) DNA polymerase
C) Restriction enzyme
D) Transposase
E) DNA ligase

Question 35

Figure 8.3

In Figure 8.3, the antibiotic chloramphenicol binds the 50S ribosome as shown. From this information you can conclude that chloramphenicol

A) Prevents transcription in prokaryotes.
B) Prevents mRNA- ribosome binding.
C) Prevents translation in prokaryotes.
D) Prevents translation in eukaryotes.
E) Prevents transcription in eukaryotes.

Question 36

An enzyme that cuts and seals DNA.

A) DNA ligase
B) DNA polymerase
C) Restriction enzyme
D) RNA polymerase
E) Transposase

Question 37

Figure 8.4

In Figure 8.4, which model of the lac operon correctly shows RNA polymerase, lactose, and repressor protein when the structural genes are being transcribed?

A) a
B) b
C) c
D) d
E) e

Question 38

Genetic change in bacteria can be brought about by

A) Conjugation.
B) Transduction.
C) Transformation.
D) Mutation.
E) All of the above.

Question 39

Which of the following statements is false?

A) DNA polymerase joins nucleotides in one direction only.
B) Multiple replication forks are possible on a bacterial chromosome.
C) The leading strand of DNA is made continuously.
D) The lagging strand of DNA is started by an RNA primer.
E) DNA replication proceeds in one direction around the bacterial chromosome.

Question 40

A gene is best defined as

A) A segment of DNA.
B) Three nucleotides that code for an amino acid.
C) A transcribed unit of DNA.
D) A sequence of nucleotides in RNA that codes for a functional product.
E) A sequence of nucleotides in DNA that codes for a functional product.

Question 41

Figure 8.2

In Figure 8.2, base 2 is attached to

A) Thymine.
B) Deoxyribose.
C) Phosphate.
D) Ribose.
E) Can't tell.