Question 1

Name the three usual phases of bacterial growth in a liquid medium.

Accepted Answer

lag (phase),log (phase),stationary (phase)

Question 2

Explain when,why,and how recombination in bacteria is like crossing over in diploid cells.

Accepted Answer

Both bacterial recombination and crossing over during meiosis require several factors.First,both processes require nicking of DNA.In bacteria,this is when the DNA is nicked in preparation for the transfer of single-stranded DNA via conjugation.In eukaryotes,one strand of the DNA is nicked during the formation of chiasmata.This allows for strand invasion and crossing over between homologous chromosomes.
Second,both processes use similar enzymes to mediate recombination.DNA helicases are involved in relieving torsional strain in the circular and linear chromosomes.Ligases are necessary for repairing the phosphodiester bonds within the DNA backbone that were created by the single-stranded breaks.Single-stranded binding proteins (SSBs)assist in stabilizing the otherwise unstable ssDNA and allow it to undergo processes such as replication,recombination,and transcription.
Third,both processes require pairing of homologous sequences.In bacteria,when the chromosome DNA from the donor cell is transferred to a recipient bacterium,the homologous parts of the donor and recipient DNA molecules can undergo recombination that leads to a change in the genotype of the recipient cell.In eukaryotes,proper pairing of homologous sequences is necessary for even exchange of chromosomes during crossing over.If homologous sequences are unevenly pairing,this can result in a region of chromosome being deleted or duplicated in the resulting gametes.

Question 3

In phi X 174 phage,whose genome is a single-stranded,circular,DNA known as the - strand,replication occurs by the rolling circle method.In which order must the events of replication occur?

Accepted Answer

A) nicking of the - strand,binding of relaxase protein to the 5′ end,DNA synthesis of a + strand,separation of + from - strands,circularization of both strands 
B) synthesis of a + strand,nicking at the origin,binding of protein to the 5′ end,DNA synthesis,displacement of the + strand when replication passes the origin,circularization of the + strand 
C) synthesis of a + strand,nicking of both strands to separate them,recircularization of both strands 
D) binding of a protein at the origin of the - strand,synthesis of a + strand,release of the + strand 
A) nicking of the - strand,binding of relaxase protein to the 5′ end,DNA synthesis of a + strand,separation of + from - strands,circularization of both strands 
B) synthesis of a + strand,nicking at the origin,binding of protein to the 5′ end,DNA synthesis,displacement of the + strand when replication passes the origin,circularization of the + strand 
C) synthesis of a + strand,nicking of both strands to separate them,recircularization of both strands 
D) binding of a protein at the origin of the - strand,synthesis of a + strand,release of the + strand B

Question 4

Refer to this text to answer the following questions.
Bacterial gene transfer is also used in the lab to introduce genes into organisms of different species,genera,phyla,or even kingdoms or domains.A major example is the use of a Ti plasmid of the soil bacterium Agrobacterium tumefaciens to transfer genes into dicotyledonous plants.The bacterium infects the plant root in the soil and transfers some of the Ti plasmid genes (T DNA)into the plant nucleus.Recombination may occur,and T DNA expression is controlled by plant compounds generated in response to wounding and infection.
-Benzer's analysis of phage genomes included deletion mapping.Since recombination could not occur in the area of a deletion,an infection by two phage strains,one of which has a deletion and the other a point mutation,which results in no wild-type recombinants being produced indicates ________?

Accepted Answer

A) that the deletion includes the position of the point mutation in the same gene 
B) that the deletion includes the position of the point mutation in a different gene 
C) that the point mutation is dominant 
D) that the point mutation is recessive 
E) the distance between the two types of mutation 
A) that the deletion includes the position of the point mutation in the same gene 
B) that the deletion includes the position of the point mutation in a different gene 
C) that the point mutation is dominant 
D) that the point mutation is recessive 
E) the distance between the two types of mutation

Question 5

Why does conjugation with an Hfr donor result in a much higher rate of gene transfer than conjugation with an F⁺ donor?

Accepted Answer

A) An F⁺ donor makes fewer pili. 
B) An F⁺ donor's T strand is slow to reach the pilus. 
C) The Hfr donor transfers genes from the chromosome and not the plasmid. 
D) The Hfr donor segment must undergo recombination in the recipient. 
E) The F⁺ donor segment must undergo recombination in the recipient. 
A) An F⁺ donor makes fewer pili. 
B) An F⁺ donor's T strand is slow to reach the pilus. 
C) The Hfr donor transfers genes from the chromosome and not the plasmid. 
D) The Hfr donor segment must undergo recombination in the recipient. 
E) The F⁺ donor segment must undergo recombination in the recipient.

Question 6

To integrate an F plasmid's genes into a host chromosome,there must be DNA recombination at homologous regions on the two circular strands.What is the minimum number of such crossover events needed for integration?

Accepted Answer

A) 1 
B) 2 
C) 3 
D) 4 
E) 8 
A) 1 
B) 2 
C) 3 
D) 4 
E) 8

Question 7

What is meant by a mutation that Benzer referred to as nonrevertible?

Accepted Answer

The answer of What is meant by a mutation that...

Question 8

If you count 73 plaques on a bacterial plate when you had added 0.1 ml of a 10⁻⁴ dilution of phage,what was the initial concentration of the (undiluted)phage?

Accepted Answer

73 × 10⁴ ×

Question 9

Name the two cycles in which bacteriophages act when they infect bacteria.

Accepted Answer

The answer of Name the two cycles in which bacteriophages...

Question 10

In his analysis of rII in phage,Benzer assayed complementation.Suppose you try your hand at this with several mutants and get the following results (+ = complementation): 42 and 62 +
42 and 83 -
62 and 63 -
62 and 74 +
42 and 74 -
42 and 75 +
62 and 75 -
Mutation 42 has previously been shown to be in a different gene than mutation 62.What can you conclude?

Accepted Answer

A) Mutations 42 and 75 are in the same gene. 
B) Mutations 62 and 74 are in the same gene. 
C) Mutations 62,63,and 74 are in the same gene. 
D) Mutations 42 and 74 are in the same gene. 
E) Mutation 63 is in a gene with neither 62 nor 42. 
A) Mutations 42 and 75 are in the same gene. 
B) Mutations 62 and 74 are in the same gene. 
C) Mutations 62,63,and 74 are in the same gene. 
D) Mutations 42 and 74 are in the same gene. 
E) Mutation 63 is in a gene with neither 62 nor 42.

Question 11

In an imagined transduction experiment with alleles a⁺,b⁺,and c⁺,a⁺ alone was transduced into an auxotroph 1400 times,b⁺ alone 1200 times,and c⁺ alone 970 times.Genes a⁺ and b⁺ were both found 10 times,b⁺ and c⁺ 2 times,and a⁺ and c⁺ one time.What can you conclude?

Accepted Answer

A) Cotransduction is too infrequent to be used to map genes. 
B) Genes a and c cotransduce only accidentally. 
C) Genes a and b are more closely linked than a and c or b and c. 
D) Genes a and c are found together only if double crossovers have occurred. 
E) Transduction of gene c is very rare. 
A) Cotransduction is too infrequent to be used to map genes. 
B) Genes a and c cotransduce only accidentally. 
C) Genes a and b are more closely linked than a and c or b and c. 
D) Genes a and c are found together only if double crossovers have occurred. 
E) Transduction of gene c is very rare.

Question 12

An F′ donor includes F DNA plus a segment of bacterial chromosome DNA.If conjugation is interrupted before the entire F′ chromosome transfers,what could be the expected consequences?

Accepted Answer

A) integration of some but not all F′ genes into the recipient's chromosome 
B) a smaller F′ plasmid than had been present in the donor 
C) failure of the F′ strand to circularize in the recipient 
D) change of the recipient from F⁻ to F⁺ 
E) formation of a recipient that is a stable partial diploid 
A) integration of some but not all F′ genes into the recipient's chromosome 
B) a smaller F′ plasmid than had been present in the donor 
C) failure of the F′ strand to circularize in the recipient 
D) change of the recipient from F⁻ to F⁺ 
E) formation of a recipient that is a stable partial diploid

Question 13

In conjugation,as the 5′ end of the T strand begins to move across the pilus,what form of replication occurs in the donor cell?

Accepted Answer

rolling ci

Question 14

Refer to this text to answer the following questions.
Bacterial gene transfer is also used in the lab to introduce genes into organisms of different species,genera,phyla,or even kingdoms or domains.A major example is the use of a Ti plasmid of the soil bacterium Agrobacterium tumefaciens to transfer genes into dicotyledonous plants.The bacterium infects the plant root in the soil and transfers some of the Ti plasmid genes (T DNA)into the plant nucleus.Recombination may occur,and T DNA expression is controlled by plant compounds generated in response to wounding and infection.
-Assuming you have appropriately engineered the Ti plasmid to carry the gene in question,how could you best and most safely test whether your potatoes are now working as a vaccine?

Accepted Answer

A) Feed the engineered potato to a population at high risk for cholera. 
B) Cook the potatoes to denature the toxin and feed them to mice susceptible to cholera. 
C) Feed pieces of raw potato to susceptible mice and test them for antibodies. 
D) Emulsify the potatoes in a liquid that can be injected into experimental animals. 
A) Feed the engineered potato to a population at high risk for cholera. 
B) Cook the potatoes to denature the toxin and feed them to mice susceptible to cholera. 
C) Feed pieces of raw potato to susceptible mice and test them for antibodies. 
D) Emulsify the potatoes in a liquid that can be injected into experimental animals.

Question 15

Describe two features of a plasmid.

Accepted Answer

two of the following

Question 16

How are selective media used in studying bacterial recombination?

Accepted Answer

Selective media permits certain bacteria

Question 17

Seymour Benzer's fine structure studies of genomes used mutations found in specific regions of what kind of genome?

Accepted Answer

bacterioph

Question 18

What distinguishes generalized versus specialized transduction?

Accepted Answer

generalized uses lyt

Question 19

A competent Hemophilus strain is individually transformed by three genes (a,b,and c)at a rate of 0.002% each.However,cotransformation frequencies for each pair are as follows: a and b 0.38 %
A and c 0.72%
B and c 0.19%
What is the correct conclusion from this data?

Accepted Answer

A) Genes b and c are farthest apart. 
B) Gene order is c,b,a. 
C) Cotransformation of b and c is so frequent,they must be one gene. 
D) Gene a is closer to b than to c. 
E) Genes a and c are farthest apart. 
A) Genes b and c are farthest apart. 
B) Gene order is c,b,a. 
C) Cotransformation of b and c is so frequent,they must be one gene. 
D) Gene a is closer to b than to c. 
E) Genes a and c are farthest apart.

Question 20

What is the role of the relaxosome in conjugation?

Accepted Answer

binds to F origin,or

Name the three usual phases of bacterial growth in a liquid medium.

Explain when,why,and how recombination in bacteria is like crossing over in diploid cells.

In phi X 174 phage,whose genome is a single-stranded,circular,DNA known as the - strand,replication occurs by the rolling circle method.In which order must the events of replication occur?

Why does conjugation with an Hfr donor result in a much higher rate of gene transfer than conjugation with an F⁺ donor?

To integrate an F plasmid's genes into a host chromosome,there must be DNA recombination at homologous regions on the two circular strands.What is the minimum number of such crossover events needed for integration?

What is meant by a mutation that Benzer referred to as nonrevertible?

If you count 73 plaques on a bacterial plate when you had added 0.1 ml of a 10⁻⁴ dilution of phage,what was the initial concentration of the (undiluted)phage?

Name the two cycles in which bacteriophages act when they infect bacteria.

In an imagined transduction experiment with alleles a⁺,b⁺,and c⁺,a⁺ alone was transduced into an auxotroph 1400 times,b⁺ alone 1200 times,and c⁺ alone 970 times.Genes a⁺ and b⁺ were both found 10 times,b⁺ and c⁺ 2 times,and a⁺ and c⁺ one time.What can you conclude?

An F′ donor includes F DNA plus a segment of bacterial chromosome DNA.If conjugation is interrupted before the entire F′ chromosome transfers,what could be the expected consequences?

In conjugation,as the 5′ end of the T strand begins to move across the pilus,what form of replication occurs in the donor cell?

Describe two features of a plasmid.

How are selective media used in studying bacterial recombination?

Seymour Benzer's fine structure studies of genomes used mutations found in specific regions of what kind of genome?

What distinguishes generalized versus specialized transduction?

A competent Hemophilus strain is individually transformed by three genes (a,b,and c)at a rate of 0.002% each.However,cotransformation frequencies for each pair are as follows: a and b 0.38 % A and c 0.72% B and c 0.19% What is the correct conclusion from this data?

What is the role of the relaxosome in conjugation?

The Molecular Basis of Heredity, Variation, and Evolution

Transmission Genetics

Cell Division and Chromosome Heredity

Gene Interaction

Genetic Linkage and Mapping in Eukaryotes

DNA Structure and Replication

Molecular Biology and Transcription and Rna Processing

The Molecular Biology of Translation

The Integration of Genetic Approaches: Understanding Sickle Cell Disease

Chromosome Structure

Gene Mutation, DNA Repair, and Homologous Recombination

Chromosome Aberrations and Transposition

Regulation of Gene Expression in Bacteria and Bacteriophage

Regulation of Gene Expression in Eukaryotes

Forward Genetics and Recombinant DNA Technology

Applications of Recombinant DNA Technology and Reverse Genetics

Genomics: Genetics From a Whole-Genome Perspective

Cytoplasmic Inheritance and the Evolution of Organelle Genomes

Developmental Genetics

Genetic Analysis of Quantitative Traits

Population Genetics and Evolution

Filters

Exam 6: Genetic Analysis and Mapping in Bacteria and Bacteriophage

Name the three usual phases of bacterial growth in a liquid medium.

Explain when,why,and how recombination in bacteria is like crossing over in diploid cells.

In phi X 174 phage,whose genome is a single-stranded,circular,DNA known as the - strand,replication occurs by the rolling circle method.In which order must the events of replication occur?

Why does conjugation with an Hfr donor result in a much higher rate of gene transfer than conjugation with an F⁺ donor?

To integrate an F plasmid's genes into a host chromosome,there must be DNA recombination at homologous regions on the two circular strands.What is the minimum number of such crossover events needed for integration?

What is meant by a mutation that Benzer referred to as nonrevertible?

If you count 73 plaques on a bacterial plate when you had added 0.1 ml of a 10⁻⁴ dilution of phage,what was the initial concentration of the (undiluted)phage?

Name the two cycles in which bacteriophages act when they infect bacteria.

In an imagined transduction experiment with alleles a⁺,b⁺,and c⁺,a⁺ alone was transduced into an auxotroph 1400 times,b⁺ alone 1200 times,and c⁺ alone 970 times.Genes a⁺ and b⁺ were both found 10 times,b⁺ and c⁺ 2 times,and a⁺ and c⁺ one time.What can you conclude?

An F′ donor includes F DNA plus a segment of bacterial chromosome DNA.If conjugation is interrupted before the entire F′ chromosome transfers,what could be the expected consequences?

In conjugation,as the 5′ end of the T strand begins to move across the pilus,what form of replication occurs in the donor cell?

Describe two features of a plasmid.

How are selective media used in studying bacterial recombination?

Seymour Benzer's fine structure studies of genomes used mutations found in specific regions of what kind of genome?

What distinguishes generalized versus specialized transduction?

A competent Hemophilus strain is individually transformed by three genes (a,b,and c)at a rate of 0.002% each.However,cotransformation frequencies for each pair are as follows: a and b 0.38 % A and c 0.72% B and c 0.19% What is the correct conclusion from this data?

What is the role of the relaxosome in conjugation?

The Molecular Basis of Heredity, Variation, and Evolution

Transmission Genetics

Cell Division and Chromosome Heredity

Gene Interaction

Genetic Linkage and Mapping in Eukaryotes

DNA Structure and Replication

Molecular Biology and Transcription and Rna Processing

The Molecular Biology of Translation

The Integration of Genetic Approaches: Understanding Sickle Cell Disease

Chromosome Structure

Gene Mutation, DNA Repair, and Homologous Recombination

Chromosome Aberrations and Transposition

Regulation of Gene Expression in Bacteria and Bacteriophage

Regulation of Gene Expression in Eukaryotes

Forward Genetics and Recombinant DNA Technology

Applications of Recombinant DNA Technology and Reverse Genetics

Genomics: Genetics From a Whole-Genome Perspective

Cytoplasmic Inheritance and the Evolution of Organelle Genomes

Developmental Genetics

Genetic Analysis of Quantitative Traits

Population Genetics and Evolution

Filters