Deck 8: Microbial Genetics

Question 1

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

A)DNA to break.
B)bonding between adjacent thymines.
C)base substitutions.
D)the formation of highly reactive ions.
E)the cells to get hot.

Answer 1

D

Question 2

Which of the following is NOT a product of transcription?

A)a new strand of DNA
B)rRNA
C)tRNA
D)mRNA

Answer 2

A

Question 3

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

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

Answer 3

A

Question 4

Which of the following statements about bacteriocins is FALSE?

A)The genes coding for them are on plasmids.
B)They cause food-poisoning symptoms.
C)They can be used to identify certain bacteria.
D)Bacteriocins kill bacteria.

Question 5

Figure 8.2

In Figure 8.2,base 5 (and ONLY the base)is covalently bound/attached to

A)ribose.
B)phosphate.
C)deoxyribose.
D)thymine.
E)The answer cannot be determined based on the information provided.

Question 6

Synthesis of a repressible enzyme is stopped by the

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

Question 7

Figure 8.2

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

A)adenine
B)thymine
C)cytosine
D)guanine
E)uracil

Question 8

The DNA damage caused by ultraviolet radiation is

A)never repaired.
B)repaired during transcription.
C)repaired during translation.
D)cut out and replaced.
E)repaired by DNA replication.

Question 9

Which of the following pairs is mismatched?

A)DNA polymerase - makes a molecule of DNA from a DNA template
B)RNA polymerase - makes a molecule of RNA from an RNA template
C)DNA ligase - joins segments of DNA
D)transposase - cuts DNA backbone,leaving "sticky ends"
E)DNA gyrase - relaxes supercoiling in DNA ahead of the replication fork

Question 10

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

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

Question 11

Which of the following statements is FALSE?

A)DNA polymerase joins nucleotides in one direction (5' to 3')only.
B)The leading strand of DNA is made continuously.
C)The lagging strand of DNA is started by an RNA primer.
D)DNA replication proceeds in only one direction around the bacterial chromosome.
E)Multiple replication forks are possible on a bacterial chromosome.

Question 12

Genetic change in bacteria can be brought about by

A)mutation.
B)conjugation.
C)transduction.
D)transformation.
E)All of the answers are correct.

Question 13

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 F⁺,leu⁺,his⁺
C)1 will remain the same; recombination may occur in 2
D)1 will become F⁻,leu⁺,his⁺; 2 will become Hfr,leu+,his+
E)The answer cannot be determined based on the information provided.

Question 14

Figure 8.2

In Figure 8.2,if base 4 is adenine,what is base 11' (remember the complimentary configuration of bases in DNA)?

A)adenine
B)thymine
C)cytosine
D)guanine
E)uracil

Question 15

A gene is defined as

A)any random segment of DNA.
B)three nucleotides that code for an amino acid.
C)a sequence of nucleotides in DNA that codes for a functional product.
D)a sequence of nucleotides in RNA that codes for a functional product.
E)the RNA product of a transcribed section of DNA.

Question 16

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

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

Question 17

Which of the following statements regarding a bacterium that is R⁺ is FALSE?

A)It possesses a plasmid.
B)R⁺ can be transferred to a cell of the same species.
C)It is resistant to certain drugs and heavy metals.
D)It is F⁺.
E)R⁺ can be transferred to a different species.

Question 18

Figure 8.1
In Figure 8.1,which colonies are streptomycin-resistant and leucine-requiring?

A)1,2,3,and 9
B)3 and 9
C)4,6,and 8
D)4 and 8
E)5 and 6

Question 19

In Table 8.1,what will be the result of conjugation between cultures 1 and 2 (reminder: F+ has a different meaning than Hfr)?

A)1 will remain the same; 2 will become F⁺,leucine⁻,histidine⁻
B)1 will become F⁻,leu⁺,his⁺; 2 will become F⁺,leu⁻,his⁻
C)1 will become F⁻,leu⁻,his⁻; 2 will remain the same
D)1 will remain the same; 2 will become F⁺,leu⁺,his⁺
E)1 will remain the same; 2 will become F⁺ and recombination may occur

Question 20

DNA is constructed of

A)a single strand of nucleotides with internal hydrogen bonding.
B)two complementary strands of nucleotides bonded A-C and G-T.
C)two strands of nucleotides running in an antiparallel configuration.
D)two strands of identical nucleotides in a parallel configuration with hydrogen bonds between them.
E)None of the answers is correct.

Question 21

Conjugation differs from reproduction because conjugation

A)replicates DNA.
B)transfers DNA vertically,to new cells.
C)transfers DNA horizontally,to nearby cells without those cells undergoing replication.
D)transcribes DNA to RNA.
E)copies RNA to make DNA.

Question 22

An enzyme that catalyzes the cutting and resealing of DNA,and is translated from insertion sequences,is

A)RNA polymerase.
B)DNA ligase.
C)DNA helicase.
D)transposase.
E)DNA polymerase.

Question 23

An enzyme that makes covalent bonds between Okazaki fragments in the lagging strand of DNA being replicated is

A)RNA polymerase.
B)DNA ligase
C)DNA helicase.
D)transposase.
E)SSBP.

Question 24

Repair of damaged DNA,in some instances and mechanisms,might be viewed as a race between an endonuclease and

A)DNA ligase.
B)DNA polymerase.
C)helicase.
D)methylase.
E)primase.

Question 25

Figure 8.3 - Metabolic Pathway

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

A)a mutation.
B)repression.
C)feedback inhibition.
D)competitive inhibition.
E)transcription.

Question 26

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

A)a chemical mutagen.
B)DNA polymerase.
C)photolyases.
D)snRNPs.
E)UV radiation.

Question 27

Table 8.2
Codons in mRNA molecule and their corresponding amino acids

Refer to Table 8.2.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 sense strand of DNA?

A)3' UGUGCAAAGUUA 5'
B)3' AGACGTTTCAAT 5'
C)3' TCTCGTTTGTTA 5'
D)5' TGTGCTTTCTTA 3'
E)5' AGAGCTTTGAAT 3'

Question 28

Table 8.2
Codons in mRNA molecule and their corresponding amino acids

Refer to Table 8.2.When amino acid sequences from a cell cycle control protein from a patient with cancer and a healthy person are aligned,the sequence from the cancer patient indicates one amino acid has changed from phenylalanine (Phe)to leucine (Leu).A mutation in the cancer patient's DNA must have taken place.Identify the result of this DNA change in the mRNA codon that led to this change in the protein sequence.

A)UUU altered to UCU
B)UUU altered to UAU
C)UCU altered to UUA
D)CAA altered to UUU
E)UUU altered to UUA

Question 29

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

A)the primary structure of the protein
B)the secondary structure of the protein
C)the tertiary structure of the protein
D)the quaternary structure of the protein
E)The answer cannot be determined based on the information provided.

Question 30

Table 8.2
Codons in mRNA molecule and their corresponding amino acids

Refer to Table 8.2.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

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

Question 31

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

Question 32

The mechanism by which the presence of glucose inhibits the lac operon is

A)catabolite repression.
B)translation.
C)DNA polymerase.
D)repression.
E)induction.

Question 33

Figure 8.3 - Metabolic Pathway

In Figure 8.3,if enzyme A is an inducible enzyme,

A)compound C would bind to the repressor for Gene a.
B)compound A would bind to the repressor for Gene a.
C)compound B would bind to enzyme A directly.
D)compound A would react with enzyme B directly.
E)compound C would react with gene a directly.

Question 34

Table 8.2
Codons in mRNA molecule and their corresponding amino acids

Refer to Table 8.2.Identify the sequence of amino acids encoded by the following sequence of bases in a strand of DNA (pay attention to the polarity of the DNA here): 3' ATTACGCTTTGC 5'.

A)leucine-arginine-lysine-alanine
B)asparagine-arginine-lysine-alanine
C)asparagine-cysteine-valine-serine
D)Translation would stop at the first codon.
E)The answer cannot be determined based on the information provided.

Question 35

Figure 8.3 - Metabolic Pathway

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

A)always be in excess.
B)bind to Enzyme A.
C)bind to the corepressor for Gene a.
D)bind to RNA polymerase.
E)bind directly to gene a.

Question 36

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

A)RNA polymerase.
B)DNA ligase.
C)DNA helicase.
D)transposase.
E)DNA polymerase.

Question 37

Figure 8.4
In Figure 8.4,the antibiotic chloramphenicol binds the 50S large subunit of a ribosome as shown (the light gray area is the large subunit,while the black shape is the drug).From this information you can conclude that chloramphenicol

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

Question 38

Table 8.2
Codons in mRNA molecule and their corresponding amino acids

Refer to Table 8.2 The anticodon for valine is

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

Question 39

Table 8.3
Based on the information in Table 8.3,prostate cancer is probably the result of which kind of mutation?

A)analog
B)frameshift
C)missense
D)nonsense
E)None of the answers is correct.

Question 40

Table 8.2
Codons in mRNA molecule and their corresponding amino acids

Refer to Table 8.2.If an indeterminate frameshift mutation occurred (that is,one at a random location)in the sequence of bases shown below,what would be the sequence of amino acids coded for? 3' ATTACGCTTTGC

A)leucine-arginine-lysine-alanine
B)asparagine-arginine-lysine-alanine
C)asparagine-cysteine-valine-serine
D)Translation would stop at the first codon.
E)The answer cannot be determined based on the information provided.

Question 41

When two genes from two different people are sequenced and aligned,it is discovered that there are multiple sequence differences in the coding segment DNA level.However,when the proteins formed by the genes have their amino acids sequenced,there is no difference observed between the two.What is the most likely explanation for this observation?

A)The mutations are corrected at the protein level after translation has occurred.
B)The mutations lie at locations where they don't affect protein sequence due to degeneracy of the genetic code.
C)The mutations are repaired at the mRNA level after transcription has occurred,but before translation.
D)Mutations at the DNA level are not reflected in proteins produced.
E)RNA processing removes the different segments from the mRNA molecules of each person prior to translation.

Question 42

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 new recombinant cell that is lys⁺,arg⁺,amp-resistant?

A)ampicillin,lysine,arginine
B)lysine,arginine
C)ampicillin,proline,histidine,methionine
D)proline,histidine,methionine
E)ampicillin,proline,histidine,lysine

Question 43

Cell-to-cell contact is required for transduction to occur.

Question 44

Figure 8.5
In Figure 8.5,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 45

The ozone layer of the Earth has been depleted to an extent by human release of certain chemicals.What type of mutation,caused by the induction of thymine dimer formation,is more likely to occur in organisms on Earth as a result of this problem?

A)silent mutation
B)nonsense mutation
C)missense mutation
D)frameshift mutation

Question 46

The miRNAs in a cell

A)are found in prokaryotic cells.
B)are a part of the prokaryotic ribosome.
C)are a part of the eukaryotic ribosome.
D)allow different cells to produce different proteins.
E)are responsible for inducing operons.

Question 47

Recombination will always alter a cell's genotype.

Question 48

When ultraviolet light strikes DNA,it can cause a specific type of damage.How is this damage best described?

A)Thymine bases on the opposing DNA strands are covalently linked together to form a thymine dimer.
B)Thymine bases on one strand of DNA,next to each other,are covalently linked together to form a thymine dimer.
C)Adenine and thymine bases on opposing DNA strands are linked together by hydrogen bonds.
D)Adenine and thymine bases on opposing DNA strands are covalently linked together to form an AT dimer.

Question 49

Mutations that are harmful to cells occur more frequently than those that benefit cells.

Question 50

Both base substitution and frameshift mutations can result in the formation of premature stop codons.

Question 51

Bacteria usually contain multiple chromosomes.

Question 52

Bacterial cells may contain multiple genomes.

Question 53

Open-reading frames are segments of DNA in which both start and stop codons are found.

Question 54

Transduction requires a(n)________ to move DNA from one bacterial cell to another.

A)bacteriophage
B)naked DNA molecule
C)F plasmid
D)transposase enzyme

Question 55

Generalized transduction occurs when a bacteriophage inadvertently packages the wrong material into one of its newly-formed protein coats.While the source of this material may vary,it is always:

A)protein.
B)mRNA.
C)DNA.
D)tRNA.
E)miRNA.

Question 56

Transposition (insertion of a transposon into a DNA sequence)results in the formation of base substitution mutations in a cell's DNA.

Question 57

If generalized transduction is underway,packaging a piece of DNA from an infected bacterial cell into a bacteriophage protein coat,what is the likely outcome?

A)Lysis of a newly-infected cell as the transducing bacteriophage infects it and multiplies.
B)The virus particle formed in the transduction process isn't able to correctly infect a new bacterial cell.
C)A second bacterial cell infected by that transducing bacteriophage will acquire new DNA,carried by the phage from the original infected cell.
D)The infected bacterial cell will recover and survive,as the packaging of non-bacteriophage DNA into the protein coat produces nonfunctional virus particles.

Question 58

In the Ames test,any colonies that form on the control plates,in the absence of chemical being tested,should be the result of spontaneous mutations.

Question 59

Protein synthesis in eukaryotes is similar to the process in prokaryotes in that both eukaryotes and prokaryotes

A)have exons.
B)have introns.
C)require snRNPS.
D)use methionine as the "start" amino acid.
E)use codons to determine polypeptide sequences.

Question 60

The miRNAs in a cell inhibit protein synthesis by forming complementary bonds with rRNA.

Question 61

Scientists are concerned that bacteria will be resistant to all antibiotics within the next decade.Using your knowledge of genetics,describe how bacterial populations can develop drug resistance in such a short time frame.

Question 62

Could you perform the Ames test with a strain of bacteria that was auxotrophic for something other than histidine? How would the setup and execution of the experiment change,and why?

Question 63

Explain why the following statement is false: Sexual reproduction is the only mechanism for genetic change.

Question 64

What is the survival value of the semiconservative replication of DNA?

Question 65

How might gene expression processes be altered if the genetic code were not degenerate in nature?