Question 1

To demonstrate transformation of bacteria,one could:

Accepted Answer

A) extract DNA from an auxotroph and add it to prototrophic cells. 
B) extract DNA from arg- cells and add it to arg+ cells. 
C) extract DNA from arg+ cells and add it to arg- cells. 
D) extract DNA from StrS cells and add it to StrR cells. 
E) mix the DNA from arg+ and arg- cells to allow recombination. 
A) extract DNA from an auxotroph and add it to prototrophic cells. 
B) extract DNA from arg- cells and add it to arg+ cells. 
C) extract DNA from arg+ cells and add it to arg- cells. 
D) extract DNA from StrS cells and add it to StrR cells. 
E) mix the DNA from arg+ and arg- cells to allow recombination.

Question 2

A permissive bacterial strain is simultaneously infected with two strains of T4-like phage.One phage strain has the genotype a-b+,while the other is a+b-.If the map distance between markers a and b is about 10 map units,what proportion of the progeny phages are expected to have the genotype a+b+?

Accepted Answer

A) about 1/20 
B) about 1/10 
C) about 4/10 
D) about 4/5 
E) about 9/10 
A) about 1/20 
B) about 1/10 
C) about 4/10 
D) about 4/5 
E) about 9/10

Question 3

In a generalized transduction experiment,donor E.coli cells have the genotype a+c+b-,and recipient cells have the genotype a-c-b+.Pl-mediated transductants for a+ were selected,and their total genotypes were determined,with the following results:
 $$\begin{array} { l } 
\text {Genotype}&\text { Number of progeny}\
\hline a ^ { + } c ^ { + } b ^ { - } &95 \
a ^ { + } c ^ { - } b ^ { - } &205\
a ^ { + } c ^ { + } b ^ { + }& 5 \
a ^ { + } c ^ { - } b ^ { + } &\underline { 195 } \
&500
\end{array}$$
a)What is the order of the three genes?
b)What is the cotransduction frequency for:
 $a$ and $c$ ?
$a$ and $b ?$
$b$ and $c ?$

Accepted Answer

a)The donor is a⁺ c⁺ b^-,the recipient is a^-

Question 4

The three bacterial markers a,b,and c are linked,but their order is unknown.A cotransduction experiment is performed and the following results are obtained. - Markers a and b are co-transduced at a frequency of 2%.
- Markers a and c are co-transduced at a frequency of 20%.
- Markers b and c are co-transduced at a frequency of 65%.
What can be concluded about the arrangement of the three markers on the bacterial chromosome?

Accepted Answer

A) The order is a-b-c,and b is closer to a than to c. 
B) The order is a-b-c,and b is closer to c than to a. 
C) The order is a-c-b,and c is closer to b than to a. 
D) The order is b-a-c,and a is closer to b than to c. 
E) The order is b-c-a,and c is closer to a than to b. 
A) The order is a-b-c,and b is closer to a than to c. 
B) The order is a-b-c,and b is closer to c than to a. 
C) The order is a-c-b,and c is closer to b than to a. 
D) The order is b-a-c,and a is closer to b than to c. 
E) The order is b-c-a,and c is closer to a than to b.

Question 5

An F+ microbial strain would best be described as:

Accepted Answer

A) any bacterium that readily takes up naked DNA through its membrane. 
B) incapable of conjugation due to inhibitory genes on the F plasmid. 
C) a bacterial strain with specific auxotrophic characteristics. 
D) a bacterial strain that carries a phage with membrane fusion competency. 
E) a bacterium with a plasmid that confers mating competency (or fertility). 
A) any bacterium that readily takes up naked DNA through its membrane. 
B) incapable of conjugation due to inhibitory genes on the F plasmid. 
C) a bacterial strain with specific auxotrophic characteristics. 
D) a bacterial strain that carries a phage with membrane fusion competency. 
E) a bacterium with a plasmid that confers mating competency (or fertility).

Question 6

The following table contains statements that may apply to conjugation,transformation,and/or transduction.For each blank space,insert a check mark if that statement applies to that mode of DNA exchange.
 $\begin{array}{|l|l|l|l|}
\hline& \text { Transformation } & \text { Conjugation } & \text { Transduction }\
\hline \text { Bacteriophages are required for gene transfer: } & & & \
\hline \text { DNA is acquired directly from the environment. } & & & \
\hline \text { DNA is transferred via an F plasmid } & & & \
\hline \text { The movement of DNA is unidirectional from } \mathrm{F}^{+} \text {to } \mathrm{F}^{-} & & & \
\hline \begin{array}{l}
\text { The DNA is replicated via rolling circle replication } \
\text { orior to the transfer: }
\end{array} & & & \
\hline \text { The transferred DNA must recombine and replace the } & & & \
\text { DNA in the chromosome in order to be maintained. } & & & \
\hline \text { It can be used to study the dominance relationship } & & & \
\text { otween alleles via the creation of partial diploids. } & & &\
\hline
\end{array}$

Accepted Answer

The answer of The following table contains statements that may...

Question 7

The table below summarizes the results of a replica-plating experiment where a mixture of 347 E.coli strains of different genotypes were tested for their ability to grow on a variety of media. $\begin{array}{|l|c|}
\hline\text { Medium}&\text { Number of colonies that grew}\
\hline\text { complete medium (contains all amino acids, vitamins, } & \
\text { and a variety of carbon sources) } & 347 \
\hline \text { minimal medium (glucose as a carbon source) } & 261 \
\hline \text { minimal medium + ampicillin (an antibiotic) } & 51 \
\hline \text { minimal medium + methionine (an amino acid) } & 303 \
\hline \text { minimal medium + arginine (an amino acid) } & 301 \
\hline \text { minimal medium + methionine + ampicilin } & 57 \
\hline \text { minimal medium + arginine + ampicilin } & 64\
\hline
\end{array}$ 
Based on the data presented above,how many colonies are wild type (met+ arg+AmpS)?

Accepted Answer

A) 51 
B) 210 
C) 261 
D) 296 
E) 347 
A) 51 
B) 210 
C) 261 
D) 296 
E) 347

Question 8

An Hfr strain of E.coli with the genotype gly+aziRStrS is mated with an F- strain of E.coli of genotype gly-aziSStrR.Gly refers to the amino acid glycine,azi refers to sodium azide,and Str refers to the antibiotic streptomycin.Conjugation occurs and the progeny are screened on a selective medium to detect recombinants.If you wanted to select for the F- recombinant genotype gly+aziRStrR,you should use a minimal medium containing:

Accepted Answer

A) glycine. 
B) glycine,sodium azide,and streptomycin. 
C) glycine and streptomycin. 
D) sodium azide. 
E) streptomycin and sodium azide. 
A) glycine. 
B) glycine,sodium azide,and streptomycin. 
C) glycine and streptomycin. 
D) sodium azide. 
E) streptomycin and sodium azide.

Question 9

Joshua Lederberg and Edward Tatum discovered a sex-like process in bacteria using:

Accepted Answer

A) high-powered microscopy in combination with antibiotic resistant genes. 
B) populations of cells with complementing auxotrophs,and the measurement of the generation of prototrophs during microbial mixing. 
C) mutations in bacteria that inhibit the mating process. 
D) comparison of bacterial behavior to yeast behavior. 
E) chromosome sequencing and analysis. 
A) high-powered microscopy in combination with antibiotic resistant genes. 
B) populations of cells with complementing auxotrophs,and the measurement of the generation of prototrophs during microbial mixing. 
C) mutations in bacteria that inhibit the mating process. 
D) comparison of bacterial behavior to yeast behavior. 
E) chromosome sequencing and analysis.

Question 10

A double infection experiment is conducted to determine the distance between two markers in the bacteriophage RB49,a phage similar to T2 and T4.A mutation in the first marker (F13-)results in the inability to grow on E.coli strain B178,while a mutation in the second marker (P6-)prevents the phage from growing at high temperature.A permissive E.coli strain is infected with both F13- and P6- phages,and the lysate is analyzed.1002 plaques were formed on a lawn of permissive E.coli at 37ºC,and out of these 1002,49 also formed plaques on E.coli B178 at high temperature.What is the predicted frequency of phages with genotype F13+P6- in the lysate?

Accepted Answer

A) 5% 
B) 45% 
C) 47.5% 
D) 90% 
E) 95% 
A) 5% 
B) 45% 
C) 47.5% 
D) 90% 
E) 95%

Question 11

Which of the following are characteristics of an E.coli strain of genotype F-gal+lac-pur+ile-strr?

Accepted Answer

A) It can act as a donor in conjugation experiments. 
B) It can form a pilus. 
C) It can grow on minimal media where lactose is the only carbon source. 
D) It is auxotrophic for lactose. 
E) It is susceptible to streptomycin. 
A) It can act as a donor in conjugation experiments. 
B) It can form a pilus. 
C) It can grow on minimal media where lactose is the only carbon source. 
D) It is auxotrophic for lactose. 
E) It is susceptible to streptomycin.

Question 12

A gal- mutant:

Accepted Answer

A) can make its own galactose. 
B) cannot grow without galactose. 
C) cannot utilize galactose as a carbon source. 
D) can utilize galactose as a carbon source. 
E) is resistant to galactose. 
A) can make its own galactose. 
B) cannot grow without galactose. 
C) cannot utilize galactose as a carbon source. 
D) can utilize galactose as a carbon source. 
E) is resistant to galactose.

Question 13

Two bacterial strains were obtained with the following genotypes: $\begin{array}{|l|l|}
  \hline\quad\quad\quad\quad\quad& \text { Hfr: alaleu }{ }^{+} a\_{-1} \mathrm{St}^{2} \mathrm{r}^{5} \quad\quad\quad\quad\quad\quad\quad\
 \hline&F^{-}: \quad a l a^{+} l e u r a-l^{R} S t r^{R}  \
\hline
\end{array}$
 
After an uninterrupted conjugation,you want to select F- recombinants that are ala+leu+.Which of the following media would you use for this selection?

Accepted Answer

A) complete medium containing streptomycin 
B) minimal medium containing streptomycin 
C) minimal medium containing leucine and streptomycin 
D) minimal medium containing sodium azide and leucine 
E) minimal medium containing alanine,leucine,and streptomycin 
A) complete medium containing streptomycin 
B) minimal medium containing streptomycin 
C) minimal medium containing leucine and streptomycin 
D) minimal medium containing sodium azide and leucine 
E) minimal medium containing alanine,leucine,and streptomycin

Question 14

An extraterrestrial scientist is trying to obtain a genetic map of a newly discovered bacterium using standard techniques such as interrupted conjugation and Hfr mapping.She is particularly interested in three loci (ata,tic,and lan)encoding proteins that are required for the synthesis of atanine,ticovine,and lancytrine (three essential extraterrestrial amino acids),respectively.With the help of interrupted-conjugation experiments,the scientist determines that ata is the last marker to enter the recipient bacterium.
She now sets up a cross between a wild-type Hfr strain that is tertacycline sensitive and an ata-tic-lan- F- strain that is tetracycline resistant.5000 exconjugants are recovered on minimal medium plus tetracycline,ticovine,and lancytrine,and subsequently replicated onto a variety of media.
The results are as follows:
- minimal medium and tetracycline: 4704 colonies grow;
- minimal medium plus lancytrine and tetracycline: 4708 colonies grow;
- minimal medium plus tetracycline and ticovine: 4900 colonies grow.
a)Draw a genetic map of these three loci (including all the map distances).
b)Why is the scientist using tetracycline on her plates (what is the purpose)?
c)Why is she recovering the exconjugants on plates that lack atanine?

Accepted Answer

a)
\[\begin{array} { l l } 
\text { ata

Question 15

An E.coli colony grew on minimal medium supplemented with arginine and leucine.However,bacteria from this colony are unable to grow and form colonies on minimal medium supplemented with arginine and methionine.What is the genotype of the bacteria in this E.coli colony?

Accepted Answer

A) arg+leu+met- 
B) arg+leu-met+ 
C) arg+leu-met- 
D) arg-leu+met+ 
E) arg-leu-met- 
A) arg+leu+met- 
B) arg+leu-met+ 
C) arg+leu-met- 
D) arg-leu+met+ 
E) arg-leu-met-

Question 16

A new bacteriophage of E.coli was isolated from the steam tunnels of New York City.Six mutant strains (a,b,c,d,e,f)were derived from it,each having a different single point mutation for the genes A,B,C,D,E,and F.Strain BDE was mated with strain bde.The order of genes given below does not necessarily reflect the order of the genes on the chromosome.The following progeny were observed:
 $B D E \quad 376 \quad B d E \quad 21 \quad b D E \quad 99 \quad \text { bdE } \quad 5$ 
$\text { RDe } \quad  4 \quad \text { Bde  }  \quad92\quad \text {bDe } \quad 20 \quad \text { hde }  \quad382$
 a)What are the genotypes of the double crossovers,showing gene order?
b)Give the percent recombination between each pair of genes.
c)Draw a map showing the positions of the B,D,and E genes,with map distances between genes,where appropriate.
d)
 (1) Give the formula you would use to calculate the coefficient of coincidence. 
(2) Calculate the coefficient of coincidence.

e)
 (1) Give the formula you would use to calculate interference.
(2) Calculate interference and specify whether the value is positive or negative

Accepted Answer

a)BeD and bEd
b)b,d: 25%;b,e: 20%;d,e: 5

Question 17

An interrupted conjugation experiment is conducted using the following strains: Hfr StrSx+y+z+ and F- StrRx-y-z-.Samples of exconjugants are tested at regular intervals for their ability to grow on minimal medium (MM)containing streptomycin plus compound X,Y,or Z.The table below summarizes the number of colonies obtained on the different media when conjugation was interrupted after 10,15,20,or 25 minutes.

Based on these results,what is the order of entry of the four markers in question?

Accepted Answer

A) Str x y z 
B) Str y x z 
C) Str z x y 
D) y x z Str 
E) z x y Str 
A) Str x y z 
B) Str y x z 
C) Str z x y 
D) y x z Str 
E) z x y Str

Question 18

If a met-thr- Hfr strain is mated with an F- of genotype leu-thi-,prototrophic recombinants can be detected by plating the mixture on minimal:

Accepted Answer

A) medium. 
B) medium supplemented with leucine and methionine. 
C) medium supplemented with leucine and thiamine. 
D) medium supplemented with methionine,threonine,leucine,and thiamine. 
E) medium supplemented with threonine and thiamine. 
A) medium. 
B) medium supplemented with leucine and methionine. 
C) medium supplemented with leucine and thiamine. 
D) medium supplemented with methionine,threonine,leucine,and thiamine. 
E) medium supplemented with threonine and thiamine.

Question 19

From one F+ strain,three distinct Hfr strains were derived.The first three markers transferred during an Hfr X F- cross (different for each of the three Hfr)are: 
Hfr 1: ...D A →
Hfr 2: ...E B →
Hfr 3: ...E C D →
Which of the following must be the order of the genes on the bacterial chromosomal circle? (A is shown at both ends to represent circularity.Assume that the Hfr picks up all intermediates between any two represented genes.)

Accepted Answer

A) A D C E B F A 
B) A B C D F E A 
C) A C D F E B A 
D) A E F B C D A 
E) A F B D E C A 
A) A D C E B F A 
B) A B C D F E A 
C) A C D F E B A 
D) A E F B C D A 
E) A F B D E C A

Question 20

A bacterial strain is able to grow on rich medium (which contains all the amino acids,vitamins,and a variety of carbon sources)but not on minimal medium or on minimal medium supplemented with leucine.What could be the genotype(s)of this bacterial strain with respect to the arg and leu loci?

Accepted Answer

A) arg+leu- 
B) arg-leu+ 
C) arg+leu- or arg-leu+ 
D) arg-leu- or arg+leu- 
E) arg-leu- or arg-leu+ 
A) arg+leu- 
B) arg-leu+ 
C) arg+leu- or arg-leu+ 
D) arg-leu- or arg+leu- 
E) arg-leu- or arg-leu+

To demonstrate transformation of bacteria,one could:

An F⁺ microbial strain would best be described as:

Joshua Lederberg and Edward Tatum discovered a sex-like process in bacteria using:

Which of the following are characteristics of an E.coli strain of genotype F^-gal⁺lac^-pur⁺ile^-str^r?

A gal^- mutant:

Two bacterial strains were obtained with the following genotypes: Hfr: alaleu a\_ -1 :alleura-St After an uninterrupted conjugation,you want to select F^- recombinants that are ala⁺leu⁺.Which of the following media would you use for this selection?

An E.coli colony grew on minimal medium supplemented with arginine and leucine.However,bacteria from this colony are unable to grow and form colonies on minimal medium supplemented with arginine and methionine.What is the genotype of the bacteria in this E.coli colony?

If a met^-thr^- Hfr strain is mated with an F^- of genotype leu^-thi^-,prototrophic recombinants can be detected by plating the mixture on minimal:

A bacterial strain is able to grow on rich medium (which contains all the amino acids,vitamins,and a variety of carbon sources)but not on minimal medium or on minimal medium supplemented with leucine.What could be the genotype(s)of this bacterial strain with respect to the arg and leu loci?

The Genetics Revolution

Single-Gene Inheritance

Independent Assortment of Genes

Mapping Eukaryote Chromosomes by Recombination

Gene Interaction

Dna: Structure and Replication

Rna: Transcription and Processing

Proteins and Their Synthesis

Gene Isolation and Manipulation

Regulation of Gene Expression in Bacteria and Their Viruses

Regulation of Gene Expression in Eukaryotes

The Genetic Control of Development

Genomes and Genomics

The Dynamic Genome: Transposable Elements

Mutation, Repair, and Recombination

Large-Scale Chromosomal Changes

Population Genetics

The Inheritance of Complex Traits

Evolution of Genes and Traits

Filters

Exam 5: The Genetics of Bacteria and Their Viruses

To demonstrate transformation of bacteria,one could:

A permissive bacterial strain is simultaneously infected with two strains of T4-like phage.One phage strain has the genotype a-b+,while the other is a+b-.If the map distance between markers a and b is about 10 map units,what proportion of the progeny phages are expected to have the genotype a+b+?

An F+ microbial strain would best be described as:

Joshua Lederberg and Edward Tatum discovered a sex-like process in bacteria using:

Which of the following are characteristics of an E.coli strain of genotype F-gal+lac-pur+ile-strr?

A gal- mutant:

Two bacterial strains were obtained with the following genotypes: Hfr: alaleu a\_ -1 :alleura-St After an uninterrupted conjugation,you want to select F- recombinants that are ala+leu+.Which of the following media would you use for this selection?

An E.coli colony grew on minimal medium supplemented with arginine and leucine.However,bacteria from this colony are unable to grow and form colonies on minimal medium supplemented with arginine and methionine.What is the genotype of the bacteria in this E.coli colony?

If a met-thr- Hfr strain is mated with an F- of genotype leu-thi-,prototrophic recombinants can be detected by plating the mixture on minimal:

A bacterial strain is able to grow on rich medium (which contains all the amino acids,vitamins,and a variety of carbon sources)but not on minimal medium or on minimal medium supplemented with leucine.What could be the genotype(s)of this bacterial strain with respect to the arg and leu loci?

The Genetics Revolution

Single-Gene Inheritance

Independent Assortment of Genes

Mapping Eukaryote Chromosomes by Recombination

Gene Interaction

Dna: Structure and Replication

Rna: Transcription and Processing

Proteins and Their Synthesis

Gene Isolation and Manipulation

Regulation of Gene Expression in Bacteria and Their Viruses

Regulation of Gene Expression in Eukaryotes

The Genetic Control of Development

Genomes and Genomics

The Dynamic Genome: Transposable Elements

Mutation, Repair, and Recombination

Large-Scale Chromosomal Changes

Population Genetics

The Inheritance of Complex Traits

Evolution of Genes and Traits

Filters

An F⁺ microbial strain would best be described as:

Which of the following are characteristics of an E.coli strain of genotype F^-gal⁺lac^-pur⁺ile^-str^r?

A gal^- mutant:

Two bacterial strains were obtained with the following genotypes: Hfr: alaleu a\_ -1 :alleura-St After an uninterrupted conjugation,you want to select F^- recombinants that are ala⁺leu⁺.Which of the following media would you use for this selection?

If a met^-thr^- Hfr strain is mated with an F^- of genotype leu^-thi^-,prototrophic recombinants can be detected by plating the mixture on minimal: