Deck 6: Genetic Analysis and Mapping in Bacteria and Bacteriophages

Question 1

What is the adaptation hypothesis?

A)The bacteria will mutate so it can become an auxotroph.
B)The phage mutates to infect bacteria more effectively.
C)The phage mutates so it can't infect bacteria any longer.
D)The phage and bacteria both mutate so the phage becomes less virulent.
E)The phage stimulates the bacteria to mutate to become immune to the phage.

Answer 1

E

Question 2

Which of the following is true about the interrupted mating technique?

A)The recipient bacterium will choose the best genes.
B)Time of contact is not applicable to this protocol.
C)Genes are transferred from the donor to recipient in a linear fashion based upon time of contact.
D)Donor will pass only beneficial genes to the recipient.
E)Genes will be passed from the centromere.

Answer 2

C

Question 3

Assume that the gene trpA in an auxotrophic strain of E.coli is located at 27 minutes,whereas the gene pyrE is located at 81 minutes. Present an experimental scheme that would allow you to convert one of the auxotrophic strains to a prototrophic

A)F⁺ auxotroph × F^- wild type
B)Hfr auxotroph × F^- wild type
C)F⁺ wild type × F^- auxotroph
D)Hfr wild type × F^- auxotroph
E)Hfr auxotroph × F^- auxotroph

Answer 3

Hfr wild type × F^- auxotroph

Question 4

______can initiate chromosome transfer from one E.coli to another.

A)An F⁺ cell
B)An F^- cell
C)An Hfr cell
D)A plasmid
E)A temperate phage

Question 5

What is a form of recombination in bacteria that involves the F plasmid?

A)fluctuation
B)transformation
C)conjugation
D)adaptation
E)transduction

Question 6

Jacob,Wollman,and others developed a linkage map of E.coli that is based on time.What form of recombination is involved in generating a linkage map based on time?

A)transduction
B)adaptation
C)time of transfer
D)conjugation
E)transformation

Question 7

Max Delbrück presented the first evidence that bacteria are capable of spontaneous mutation.What is the name of the test that Delbrück used to demonstrate this phenomenon?

A)auxotrophic test
B)lag test
C)fluctuation test
D)prototrophic test
E)logarithmic test

Question 8

What is an R plasmid?

A)They carry a gene for resistance to an environmental attribute,such as heavy metals,and genes for the transfer of the plasmid.
B)They function in bacterial recombination.
C)They are a plasmid that can exist in the chromosome or outside the chromosome.
D)They are the plasmids that carry the F factor.
E)It is an F factor that has picked up part of a bacterial genome.

Question 9

Once an exogenous foreign piece of DNA is in the bacterial cell,it is incorporated into the bacterial genome through ______.

A)transformation
B)conjugation
C)DNA replication
D)transduction
E)crossing- over recombination

Question 10

Name the general category into which double- stranded circular extrachromosomal DNA elements such as F factors,ColE1,and R would fall.

A)r- determinant
B)plaque
C)partial diploid
D)capsid
E)plasmid

Question 11

Analyze the following growth of a bacterial colony. What is the genotype of the bacterium?

A)bio⁺,leu⁺,lac^-
B)bio⁺,thr⁺,leu⁺,met⁺
C)leu⁺,met⁺,lac⁺
D)leu⁺,met⁺,lac^-
E)bio⁺,thr⁺,lac^-

Question 12

______are bacteria that can grow on minimal medium and are assumed to be wild type.

A)Prototrophs
B)F⁺ cells
C)Auxotrophs
D)Mutants
E)Hfr

Question 13

Which of the following is true about a merozygote?

A)It can spontaneously form from an Hfr cell.
B)Merozygotes were crucial to our understanding of the formation of the sex pilus.
C)A merozygote can form if an F factor carries chromosomal DNA and is injected into an F^- cell.
D)A conjugation with an Hfr donor will never produce a merozygote.
E)It is formed from an Hfr to F⁺ cross.

Question 14

In which phase of the bacterial cell cycle do the cells grow most quickly?

A)stationary
B)fluctuation
C)log
D)adaptation
E)lag

Question 15

______bacteria contain an F factor or plasmid that is capable of initiating conjugation.______bacteria contain an F plasmid that possesses a portion of the bacterial chromosome.

A)F⁺; Merozygotes
B)F^-; F⁺
C)F⁺; Hfr
D)Merozygotes; F^-
E)F^-; Hfr

Question 16

In a bacterial cross in which the donor Hfr is a⁺b⁺ and the recipient strain F^- is a^-b^-,it is expected that recombinant bacteria______ .

A)will be a mixture of a⁺b⁺,a^-b^-,and a^-b⁺
B)will all remain a^-b^-
C)will all be a⁺b⁺
D)will be a mixture of a⁺b⁺,a^-b^-,a⁺b^-,and a^-b⁺
E)will be a mixture of a⁺b⁺ and a^-b^-

Question 17

______can exist integrated into the bacterial chromosome or as an autonomous plasmid unit in the cytosol.

A)Col plasmid
B)Temperate phages
C)Episomes
D)F' plasmid
E)R factor

Question 18

How do different strains of E.coli can reveal different linkage arrangements of genes in Hfr crosses?

A)They do not.All Hfr strains are identical.
B)Different strains may have different F factors and therefore different initiation points for chromosome transfer.
C)Hfr strains will demonstrate different areas of recombination,due to dominance and recessiveness of genes.
D)In different Hfr strains,different genes will be transferred based on where the centromere resides.
E)In different Hfr strains,genes can be in different order on the chromosome.

Question 19

______have lost,through ______,the ability to grow on minimal medium.

A)prototrophs; adaptation
B)mutants; adaptation
C)prototrophs; mutation
D)auxotrophs; mutation
E)auxotrophs; adaptation

Question 20

Describing bacterial conjugation,which of the following matings is most likely to result in a change from F^- to F⁺?

A)donor F^- recipient Hfr
B)donor Hfr recipient F⁺
C)donor Hfr recipient F^-
D)donor F⁺ recipient F^-
E)donor F^- recipient F⁺

Question 21

Which of the following is a possible outcome of the lysogenic cycle?

A)bacterial cell lysis
B)bacterial fission
C)prophage formation
D)bacterial cell lysis,prophage formation and propagation,and bacterial fission are all possible outcomes of the lysogenic cycle
E)prophage formation and propagation

Question 22

Transduction is a form of recombination in bacteria that involves______ .

A)fertility factors
B)physical contact between the bacteria involved
C)plasmids
D)5- bromouracil
E)bacteriophages

Question 23

Which of the following is an episome?

A)F factor and temperate phage
B)lytic phage
C)F factor
D)temperate and lytic phages
E)temperate phage

Question 24

Bacteriophages engage in two interactive cycles with bacteria.What are these cycles?

A)insertion and replication
B)auxotrophic and prototrophic
C)heteroduplex and homoduplex
D)lytic and lysogenic
E)negative and positive

Question 25

Assume that one counted 67 plaques on a bacterial plate where 0.1 ml of a 10^-5 dilution of phage was added to bacterial culture.What is the initial concentration of the undiluted phage?

A)6.7 × 10^-5 pfu/ml
B)0.1 × 10⁵ pfu/ml
C)6.7 × 10⁵ pfu/ml
D)67 pfu/ml
E)6.7 × 10⁷ pfu/ml pfu = plaque- forming units

Question 26

Which of the following occurs during cell lysis?

A)prophage formation
B)plaque formation
C)lysogeny
D)binary fission
E)episome propagation

Question 27

What is meant by the term cotransformation?

A)Cotransformation occurs when several linked genes are transformed simultaneously.
B)A cell can pick up more than one F factor.
C)An F^- cell can become F⁺ several times in a life cycle.
D)More than one phage infects a bacterial cell.
E)Several pieces of DNA can form heteroduplexes in a cell.

Question 28

The clearing made by bacteriophages in a "lawn" of bacteria on an agar plate is called a______ .

A)host range
B)prophage
C)clear zone
D)lysogenic zone
E)plaque

Question 29

Temperate phages are those that can enter either the______ or the______ cycle.

A)functional; nonfunctional
B)complementing; competing
C)virulent; avirulent
D)former; nonformer
E)lytic; lysogenic

Question 30

Name two forms of recombination in bacteria.

A)auxotrophic and prototrophic
B)conjugation and transduction
C)lytic and lysogenic
D)insertion and replication
E)mixed and generalized

Question 31

Which of the following statements is false?

A)A symbiotic relationship between a phage and a bacterium apparently occurs in the process of lysogeny.
B)Lysogeny is a process that occurs during transformation and conjugation.
C)A bacteriophage that can only undergo lysis is called a virulent phage.
D)A prophage can exist in a quiescent state in the bacterial chromosome.
E)Viral genomes comprise only genes for viral structure and assembly.

Question 32

A bacteriophage that is capable of entering either a lytic or a lysogenic cycle is called an______.

A)temperate bacteriophage
B)virulent bacteriophage
C)plasmid
D)plaque- forming unit
E)episome

Question 33

What are the general structural features of a prokaryotic plasmid?

A)made of protein and existing in the cytosol
B)linear double- stranded DNA integrated into the chromosome
C)proteins on the bacterial chromosome
D)circular double- stranded DNA in the cytosol
E)circular double- stranded DNA in the nucleus

Question 34

What is a bacteriophage?

A)a bacterium that infects other bacteria
B)a bacterium that infects a virus
C)a virus that exclusively undergoes the lytic cycle
D)a virus that exclusively undergoes the lysogenic cycle
E)a virus that has a bacterium as its host

Question 35

After transformation,heteroduplex formation,and resolution,the resulting daughter cells are______ .

A)both have plasmids
B)both transformed
C)both mutant
D)both wild type
E)one transformed and one nontransformed

Question 36

What is the first step in phage formation inside the bacterial cell?

A)tail formation
B)tail fibers are added
C)DNA packaging as the viral heads assemble
D)adherence to the pilus
E)lysis

Question 37

When a bacteriophage genome incorporates itself into the chromosome of the host,that phage genome is referred to as an______.

A)T4 phage
B)prophage
C)episome
D)lytic phage
E)temperate phage

Question 38

Bacteria that are in a particular physiological state to become transformed are called______ .

A)resistant
B)episomal
C)transformable
D)temperate
E)competent

Question 39

What is a plaque composed of?

A)lysed bacteria,phage,and agar
B)bacteriophage and agar
C)lysed bacteria
D)live bacteria and bacteriophage
E)bacteriophage and dead bacteria

Question 40

What is the process by which a temperate bacteriophage infects a bacterial cell and subsequently integrates its chromosome into the bacterial chromosome?

A)lysogeny
B)transduction
C)temperate
D)transformation
E)lysis

Question 41

In a mixed infection experiment,the results of an h+r and hr+ cross are as follows. How far apart are these two genes?

A)12
B)24
C)48
D)8
E)2

Question 42

To produce recombinants in phage______ .

A)one crossover is required
B)a bacterial cell must be competent
C)phage recombinants do not occur
D)the F factor must be present
E)two crossovers are required

Question 43

In Seymour Benzer's studies,if he mixed two RII phage together co- infection studies in K12 and the resulting phage always failed to lyse K12______ .

A)the two mutants were in different cistrons
B)the two mutants failed to infect bacteria
C)the two mutants were in the same cistron
D)the two mutants complemented each other
E)the two mutants represented mutations in both A and B

Question 44

A form of bacterial recombination that involves a viral intermediate is called ______.

A)plaque assay
B)transduction
C)transformation
D)conjugation
E)competency

Question 45

Viral mutations and variants are often categorized by changes in______ .

A)host range
B)viral size
C)capsid shape
D)host range and/or plaque morphology
E)plaque morphology

Question 46

In a mixed infection experiment,you study two plaque phenotypes of large l⁺ versus small l^- and bumpy b⁺ versus smooth b^- .You mix small l^- b⁺ with smooth l⁺ b^- and identify 50 small,smooth and 47 large,bumpy.How far apart are the genes?

A)490
B)99
C)49
D)1000
E)There is not enough information to calculate the distance.

Question 47

______is most likely associated with transduction.

A)Conjugation
B)Transformation
C)Lysogeny
D)factor
E)Plasmid ColE

Question 48

If two different auxotrophic strains are placed in a liquid medium culture tube,prototrophic strains can sometimes be subsequently recovered.Choose the mechanism below that would not allow this genetic change.

A)conjugation
B)transduction
C)genetic suppression
D)transformation
E)reverse mutation

Question 49

______of genes is an indication that the genes are linked.

A)Conjugation
B)Recombination
C)Reversion
D)Cotransduction
E)Transformation