Question 1

If two markers are closely linked,they will show:

Accepted Answer

A) a high frequency of recombination and a high frequency of co-transformation. 
B) a high frequency of recombination and a low frequency of co-transformation 
C) a low frequency of recombination and a high frequency of co-transformation. 
D) a low frequency of recombination and a high frequency of co-transformation 
E) the same frequency of recombination and frequency of co-transformation. 
A) a high frequency of recombination and a high frequency of co-transformation. 
B) a high frequency of recombination and a low frequency of co-transformation 
C) a low frequency of recombination and a high frequency of co-transformation. 
D) a low frequency of recombination and a high frequency of co-transformation 
E) the same frequency of recombination and frequency of co-transformation. C

Question 2

To demonstrate linkage of two markers A and B by transformation,one needs to demonstrate that the frequency of transformation by:

Accepted Answer

A) A and B is greater than the product of their individual transformation frequencies. 
B) A and B is greater than the sum of their individual transformation frequencies. 
C) A and B is less than the product of their individual transformation frequencies. 
D) A and B is less than the sum of their individual transformation frequencies. 
E) A is equal to the frequency of transformation by B. 
A) A and B is greater than the product of their individual transformation frequencies. 
B) A and B is greater than the sum of their individual transformation frequencies. 
C) A and B is less than the product of their individual transformation frequencies. 
D) A and B is less than the sum of their individual transformation frequencies. 
E) A is equal to the frequency of transformation by B. A

Question 3

A strain of E.coli has the genotype (and phenotype)leu- lac-.This notation means that this strain if bacteria is unable to:

Accepted Answer

A) metabolize the amino acid leucine and synthesize the sugar lactose. 
B) utilize the amino acid leucine and synthesize the sugar lactose. 
C) utilize the amino acid leucine and the sugar lactose. 
D) synthesize the amino acid leucine and utilize the sugar lactose. 
E) synthesize the amino acid leucine and the sugar lactose. 
A) metabolize the amino acid leucine and synthesize the sugar lactose. 
B) utilize the amino acid leucine and synthesize the sugar lactose. 
C) utilize the amino acid leucine and the sugar lactose. 
D) synthesize the amino acid leucine and utilize the sugar lactose. 
E) synthesize the amino acid leucine and the sugar lactose. D

Question 4

A bacterial chromosome has four markers,A,B,C,and D,evenly spaced throughout the circle.A generalized transducing phage will:

Accepted Answer

A) always transduce at least two of the four markers. 
B) never transduce more than one marker. 
C) transduce any of the markers by different transduction events. 
D) transduce only one specific marker such as A. 
E) pick up all the markers in one particle. 
A) always transduce at least two of the four markers. 
B) never transduce more than one marker. 
C) transduce any of the markers by different transduction events. 
D) transduce only one specific marker such as A. 
E) pick up all the markers in one particle.

Question 5

The most commonly used phage characters in the study of phage inheritance are:

Accepted Answer

A) phage morphology and host morphology. 
B) phage morphology and host range. 
C) plaque morphology and host morphology. 
D) plaque morphology and host range. 
E) plaque morphology and phage morphology. 
A) phage morphology and host morphology. 
B) phage morphology and host range. 
C) plaque morphology and host morphology. 
D) plaque morphology and host range. 
E) plaque morphology and phage morphology.

Question 6

A cross is made between an Hfr strain that is StrSa+b+d+ in genotype and an F- strain that is StrRa-b-d- in genotype.Interrupted-mating studies show that b+ enters the recipient strain last,and that the Str locus is very far away from b+,so it never enters the recipient strain.The b+ recombinants are then tested for the presence of the a+ and d+ alleles.The following data were obtained: $\begin{array} { l l l l } 
a ^ { + } & b ^ { + } & d ^ { + } & 326 \
a^ { -} & b ^ { + } & d ^ { + } & 2 \
a ^ { + } & b ^ { + } & d^ { -} & 14 \
a ^ { -}& b ^ { + } & d ^ { -}& \underline { 58 } \
& && 400
\end{array}$ 
a)What is the gene order?

Accepted Answer

A) a d b Str 
B) b a d Str 
C) b d a Str 
D) d a b Str 
E) d b a Str 
A) a d b Str 
B) b a d Str 
C) b d a Str 
D) d a b Str 
E) d b a Str

Question 7

An E.coli F- strain has the following genotype: S-U-R-I-E-C-.Three different Hfr strains,all carrying S+U+R+I+E+ and C+ markers and all having lambda phages integrated at the same specific site in their chromosomes are mated with the F strain in separate matings.The interrupted-mating results are given below.The numbers indicate time (in minutes)when different donor markers appeared in F- cells after conjugation began.Assume that the E.coli map consists of 100 minutes,and gene C is mapped at 80 minutes.
 $\begin{array}{llll}
\text { Marker'S } & \text { Hfr 1 } &\text { Hfr 2 } & \text { Hfr } 3\
\hline R & 10 & 20 & - \
I & 40 & - & 5 \
U & 25 & 5 & - \
E & - & 60 & - \
C & - & 45 & - \
S & 55 & - & 20
\end{array}$

The positions of Hfr 2,the gene C,and the polarity of Hfr 2 are given in the accompanying map.   
a)Give the gene order,starting from C and going clockwise.
b)What is the location of the origin of Hfr 1? Hfr 3?
c)What is the location of the I marker? The S marker?
d)What is the location of the lambda phage in these strains?

Accepted Answer

a)CRUISE (if counterclockwise,

Question 8

An Hfr microbial strain would best be described as:

Accepted Answer

A) any bacterium that readily takes up naked DNA through its membrane. 
B) a bacterial strain with specific auxotrophic characteristics. 
C) a bacterium containing a chromosomally integrated plasmid conferring mating competency. 
D) a bacterium carrying an Hfr phage with membrane fusion competency. 
E) a bacterium that lacks the histidine frequenase gene. 
A) any bacterium that readily takes up naked DNA through its membrane. 
B) a bacterial strain with specific auxotrophic characteristics. 
C) a bacterium containing a chromosomally integrated plasmid conferring mating competency. 
D) a bacterium carrying an Hfr phage with membrane fusion competency. 
E) a bacterium that lacks the histidine frequenase gene.

Question 9

A strain of E.coli with the genotype arg-bio-gal-TetR is able to grow on minimal medium (containing glucose as a carbon source)supplemented with:

Accepted Answer

A) the amino acid arginine and the antibiotic tetracycline. 
B) the amino acid arginine and the vitamin biotin. 
C) the amino acid arginine and the sugar galactose. 
D) the vitamin biotin and the sugar galactose. 
E) the sugar galactose and the antibiotic tetracycline. 
A) the amino acid arginine and the antibiotic tetracycline. 
B) the amino acid arginine and the vitamin biotin. 
C) the amino acid arginine and the sugar galactose. 
D) the vitamin biotin and the sugar galactose. 
E) the sugar galactose and the antibiotic tetracycline.

Question 10

In a transformation experiment,DNA of a p+q+ strain was used to transform a recipient strain that is auxotrophic for these markers.The number of each class of transformants is shown below:
 $$\begin{array} { | c | c | c | } 
\hline \text { Class } & \text { Genotype } & \text { Number } \
\hline 1 & \mathrm { p } ^ { + } \mathrm { q } ^ { + } & 405 \
\hline 2 & \mathrm { p } ^ { + } \mathrm { q } ^ { - } & 300 \
\hline 3 & \mathrm { p } ^ { - } \mathrm { q } ^ { + } & 195 \
\hline
\end{array}$$ 
a)If the total number of transformants isolated was 900,what is the co-transformation frequency for the p and q loci?
b)Use diagrams to show how each class of transformants were obtained starting with the recipient auxotroph.

Accepted Answer

a)co-transformation frequency

Question 11

Auxotrophic mutations have been extremely useful to study a number of processes in E.coli.
a)Briefly define the term "auxotrophic."
b)Suppose you were given two unlabeled tubes,one that contains a methionine auxotroph and the other that contains a leucine auxotroph.Design an experiment to determine which auxotroph is found in each tube.

Accepted Answer

a)It is a cell that is unable to synthes

Question 12

The following table contains statements pertaining to Hfr,F+,F?,and/or F- strains of bacteria.Indicate in respective boxes if the statements apply to each category by inserting a check mark (√).
 $$\begin{array} { | l | l | l | l | l | } 
\hline \text { Statement } & \text { Hfr } & \mathrm { F } ^ { + } & \mathrm { F } ^ { \prime } & \mathrm { F } ^ { - } \
\hline \text { a) Contains genes that regulate conjugation and the transfer of } & & & & \
\text { DNA from one cell to another. } & & & & \
\hline \text { b) Always acts as the recipient in conjugation. } & & & & \
\hline \text { c) F factor is inteprated into the host chromosone. } & & & & \
\hline \text { d) Carmot forn a pilus. } & & & & \
\hline \begin{array} { l } 
\text { e) F factor is in the plasnid form carrying a segrnent of } \
\text { dhromosornal DNA }
\end{array} & & & \
\hline
\end{array}$$

Accepted Answer

\[\begin{array} { | l | l | l | l | l |

Question 13

A mixed infection of an E.coli strain was performed using the h-r+ and h+r- genotypes of the T2 phage.Progeny phage were collected after lysis and plated on two E.coli strains to obtain plaque characters important for detection of parental and recombinant types.
h+ can only infect one strain of E.coli
h- can infect both strains
r+ shows slower lysis,forms small plaques
r- shows rapid lysis
In the table below,for each observed phenotype,give the genotype that would produce that phenotype,and indicate if the phenotype is parental or recombinant type.Calculate the map distance between the h and r genes using the information provided.
 $$\begin{array} { | l | l | l | l | } 
\hline \text { Plaque phenotype } & \text { Number of plaques } & \text { Plaque genotype } & \text { Parental/recombinant } \
\hline \text { cloudy, large } & 600 & & \
\hline \text { clear, small } & 480 & & \
\hline \text { cloudy, small } & 180 & & \
\hline \text { clear, large } & 180 & & \
\hline
\end{array}$$

Accepted Answer

RF% = (recombinants/total)@#LAT-DLM& 100 = map dis

Question 14

A transduction experiment was conducted using a prototrophic donor and a recipient that was auxotrophic for lys,arg,and trp.Selection was done for trp+ transductants.The trp+ transductants could be categorized into the following classes:
 $$\begin{array} { | c | c | } 
\hline \text { Genotype } & \text { Number } \
\hline \text { lys } ^ { + } a r g^ { - }  t r p ^ { + } & 10 \
\hline \text { lys}^ { - } arg ^ { + } t p ^ { + } & 13 \
\hline \text { lys} ^ { - } arg^ { - } trp ^ { + } & 82 \
\hline \text { lys } ^ { + } a r g^ + t r p ^ { + } & 1 \
\hline
\end{array}$$ 
a)Which marker is closest to trp? Explain your reasoning.
b)What is the order of the three markers? Explain your reasoning.

Accepted Answer

a)arg.arg was co-transduced with trp at

Question 15

At time zero,an Hfr strain (strain 1)was mixed with an F- strain,and at various times after mixing,samples were removed and agitated to separate conjugating cells.The cross may be written as:
 HFr 1: $a ^ { + } b ^ { + } c ^ { + } d ^ { + } e ^ { + } f ^ { + } g ^ { + } h ^ { + } S t r ^ { 5 }$ 
$\mathrm { F } : $$a^{-} b^{-}-d^{-} e^{-}f ^{-}g^{-}h^{-}S tr{ }^{R}$

No order is implied in the above listing.The samples were then plated onto selective media to measure the frequency of h+StrR recombinants that had received certain genes from the Hfr cell.The following graph shows the percentage of recombinants against time in minutes.   
a)Draw a linear map of the Hfr chromosome indicating:
(1)the point of insertion (origin).
(2)the order of the genes a+,b+,e+,g+,and h+.
(3)the shortest distance between consecutive genes on the chromosome in minutes.
b)An additional four Hfr strains (strains 2$\times$5)were obtained.Each carried the wild-type alleles of the genes listed below.They were mated individually to the same F- strain shown above (carrying the recessive alleles of all genes).With interrupted mating,the times of first appearance in minutes of individual Hfr markers in exconjugants were determined,as shown in the following chart.
 $\begin{array}{ll}
&\text { Minutes }\
\text { Hfr marker }& \mathrm{Hfr} 1& \mathrm{Hfr} 2 &\mathrm{Hfr} 3 &\mathrm{Hfr} 4 &\mathrm{Hfr} 5\
a^{+} && 2&&20 \
b^{+} && &11\
c^{+} & &12 &28&10\
d^{+} & &24&&&5\
e^{+} &&&&35&50 \
f^{+} &&&88&&35\
g^{+} &\
h^{+} 
\end{array}$

Draw the genetic map showing:
(1)the positions of genes a$\times$through h.
(2)the origins of the Hfrs (including strain 1).
(3)the orientation of the origins.
(4)the shortest distance between consecutive genes or origins.

Accepted Answer

a) @#IMG-DLM&_TB3928_00
 b) @#IMG-DLM&_TB3928_00

Question 16

Two labs calculated cotransduction frequencies for the genes A and B.Lab 1 calculated 0.63,and lab 2 calculated 0.47.Which lab reported the genes to be closer together?

Accepted Answer

Lab 1.A higher cotransduction

Question 17

Bernard Davis tested the "cross-feeding" interpretation of some data that showed the phenotype of one microbe as capable of being changed by another microbe.His contribution can be summarized as:

Accepted Answer

A) using one strain of microbes as food for another,and then evaluating the impact upon microbial phenotype. 
B) combining microbes with complementing auxotrophs in a single tube and then analyzing the cells of gene exchange. 
C) placing a barrier between bacterial strains with complementing auxotrophs to assess whether contact between cells was required for genetic exchange. 
D) using fungi to feed bacterial strains with unusual auxotrophic mutations. 
E) Davis was not a significant contributor to this research question. 
A) using one strain of microbes as food for another,and then evaluating the impact upon microbial phenotype. 
B) combining microbes with complementing auxotrophs in a single tube and then analyzing the cells of gene exchange. 
C) placing a barrier between bacterial strains with complementing auxotrophs to assess whether contact between cells was required for genetic exchange. 
D) using fungi to feed bacterial strains with unusual auxotrophic mutations. 
E) Davis was not a significant contributor to this research question.

Question 18

An E.coli culture is growing in (rich)liquid medium.A representative sample of this culture is plated on solid rich medium,and 950 colonies grow on this medium.A sample of bacteria from each of these colonies is then plated on minimal medium,and only 108 of these samples grow into a colony.What proportion of the bacteria in the original liquid culture are auxotrophic?

Accepted Answer

A) 0.102 
B) 0.114 
C) 0.796 
D) 0.886 
E) 0.898 
A) 0.102 
B) 0.114 
C) 0.796 
D) 0.886 
E) 0.898

Question 19

A bacterium with the genotype met+his+lys-arg+ has been transformed with DNA from a second bacterium that has the genotype met+his-lys+arg-.   
Following the transformation,scientists streaked a sample of a transformed bacterium onto several different plates that contain different nutritional supplements in order to determine the transformant's genotype.Using the results of the experiments (shown below),determine what crossovers occurred to produce the bacterium.On the above diagram,draw the crossovers that are necessary to produce a bacterium that fits the observed growth profile.

Accepted Answer

The bacteria must be met⁺his^-lys

Question 20

If two bacterial genes are very closely linked (less than one map unit apart),then their frequency of cotransduction will be:

Accepted Answer

A) less than 1%. 
B) more than 1%,but no more than 25%. 
C) between 25% and 50%. 
D) between 50% and 75%. 
E) very high,almost 100%. 
A) less than 1%. 
B) more than 1%,but no more than 25%. 
C) between 25% and 50%. 
D) between 50% and 75%. 
E) very high,almost 100%.

If two markers are closely linked,they will show:

To demonstrate linkage of two markers A and B by transformation,one needs to demonstrate that the frequency of transformation by:

A strain of E.coli has the genotype (and phenotype)leu^- lac^-.This notation means that this strain if bacteria is unable to:

A bacterial chromosome has four markers,A,B,C,and D,evenly spaced throughout the circle.A generalized transducing phage will:

The most commonly used phage characters in the study of phage inheritance are:

An Hfr microbial strain would best be described as:

A strain of E.coli with the genotype arg^-bio^-gal^-Tet^R is able to grow on minimal medium (containing glucose as a carbon source)supplemented with:

Two labs calculated cotransduction frequencies for the genes A and B.Lab 1 calculated 0.63,and lab 2 calculated 0.47.Which lab reported the genes to be closer together?

Bernard Davis tested the "cross-feeding" interpretation of some data that showed the phenotype of one microbe as capable of being changed by another microbe.His contribution can be summarized as:

If two bacterial genes are very closely linked (less than one map unit apart),then their frequency of cotransduction will be:

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

If two markers are closely linked,they will show:

To demonstrate linkage of two markers A and B by transformation,one needs to demonstrate that the frequency of transformation by:

A strain of E.coli has the genotype (and phenotype)leu- lac-.This notation means that this strain if bacteria is unable to:

A bacterial chromosome has four markers,A,B,C,and D,evenly spaced throughout the circle.A generalized transducing phage will:

The most commonly used phage characters in the study of phage inheritance are:

An Hfr microbial strain would best be described as:

A strain of E.coli with the genotype arg-bio-gal-TetR is able to grow on minimal medium (containing glucose as a carbon source)supplemented with:

Two labs calculated cotransduction frequencies for the genes A and B.Lab 1 calculated 0.63,and lab 2 calculated 0.47.Which lab reported the genes to be closer together?

Bernard Davis tested the "cross-feeding" interpretation of some data that showed the phenotype of one microbe as capable of being changed by another microbe.His contribution can be summarized as:

If two bacterial genes are very closely linked (less than one map unit apart),then their frequency of cotransduction will be:

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

A strain of E.coli has the genotype (and phenotype)leu^- lac^-.This notation means that this strain if bacteria is unable to:

A strain of E.coli with the genotype arg^-bio^-gal^-Tet^R is able to grow on minimal medium (containing glucose as a carbon source)supplemented with: