Horizontal Gene Transfer

Question 1

Bacterial gene transfer by –requires physical contact between cells of the two strains.

Answer 1

conjugation

Question 2

the process is controlled by genes of extrachromosomal elements

Answer 2

conjugation

Question 3

the process requires genetic information for transfer which is found in the F plasmid DNA of the donor cell

Answer 3

conjugation

Question 4

the process is characterized by infection of the donor cell by a bacteriophage

Answer 4

transduction

Question 5

DNA enters the “recipient” cell via DNA transporters

Answer 5

transformation

Question 6

DNA is released after the “donor” cell lyses

Answer 6

transformation

Question 7

transforming elements absorb across the cell membrane

Answer 7

transformation

Question 8

It is the transfer of DNA between organisms by a manner independent of asexual or sexual reproduction.

Answer 8

horizontal gene transfer

Question 9

LGT has converted some benign bacteria into – that cause disease.

Answer 9

pathogens

Question 10

LGT provides for the – of complex traits

Answer 10

rapid evolution

Question 11

– contributes to antibiotic resistance in many bacterial species.

Answer 11

LGT

Question 12

LGT allows an organism to instantly acquire whole segments of chromosomes containing –.

Answer 12

multiple, functionally related genes

Question 13

LGT provides for rapid – evolution

Answer 13

genome

Question 14

1. Drug resistance can evolve rapidly through lateral gene transfer and physicians look to the CDC for warnings and recommendations for treatments in order to best serve their patients.
2. Drug resistance can be transmitted through horizontal gene transfer from prokaryotes to humans and the CDC must remain vigilant to decrease the spread of antibiotic resistance among species.
3. Drug resistance can evolve rapidly through horizontal gene transfer that stimulates the evolution of pathogens and the CDC tries to prevent the rise of new bacterial species.

Answer 14

1. Drug resistance can evolve rapidly through lateral gene transfer and physicians look to the CDC for warnings and recommendations for treatments in order to best serve their patients.

Question 15

What are the short-term implications of these frequent changes for physicians and clinics that treat sexually transmitted diseases like gonorrhea and for individuals infected with gonorrhea?

• Physicians carefully monitor progress to recovery in their patients.
• Physicians report the occurrence of new, drug-resistant strains to the CDC.
• Physicians give partial antibiotic treatment to patients to develop antibiotic resistant strains for further studies.
• Physicians give up-to-date treatments to their patients.

Answer 15

• Physicians carefully monitor progress to recovery in their patients.
• Physicians report the occurrence of new, drug-resistant strains to the CDC.
• Physicians give up-to-date treatments to their patients.

Question 16

What are the long-term implications of these frequent changes in treatment recommendations for the patient population?
Select the five correct answers.
- Physicians constantly change recommendations for adequate treatment.
- Physicians provide continued resources for the CDC.
- Physicians limit the horizontal gene transfer.
- Physicians promote the development and spread of antibiotic resistant bacteria.
- Physicians provide continued resources for research institutions to study bacterial antibiotic resistance.
- Physicians study the mechanisms and consequences of lateral gene transfer and its role in the evolution of antibiotic resistance.
- The government supports the funding of basic research.

Answer 16

• Physicians constantly change recommendations for adequate treatment.
• Physicians provide continued resources for the CDC.
• Physicians provide continued resources for research institutions to study bacterial antibiotic resistance.
• Physicians study the mechanisms and consequences of lateral gene transfer and its role in the evolution of antibiotic resistance.
• The goverment supports the funding of basic research.

Question 17

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?

Answer 17

1

Question 18

– require a supplement to grow

Answer 18

auxotrophs

Question 19

will grow in the presence or absence of the supplement

Answer 19

prototrophs

Question 20

Once conjugation begins, the Hfr strain starts transferring the integrated – and a copy of the Hfr chromosome attached to it

Answer 20

F plasmid

Question 21

The appearance of prototrophic colonies in an interrupted conjugation experiment indicates that a wild-type locus (from the Hfr donor) has entered the recipient cell and – into its genome.

Answer 21

recombined

Question 22

– is a technique that allows the same bacterial colonies to be plated onto different media.

Answer 22

Replica plating

Question 23

least frequent exconjugant genotype has the – crossovers

Answer 23

most

Question 24

During conjugation, cells gain genes in the order they occur in the donor cell chromosome. Genes that are – the origin of transfer will be transferred first.

Answer 24

near

Question 25

TThe distance between genes on the gene map is measured in -- because the distance between genes is measured by the time it takes for the gene to be transferred from the host cell into the recipient cell. This distance can be determined by looking at the first appearance of each phenotype on the graph.

Answer 25

minutes

Question 26

What role does the blender play in the experiment? shears the sex pili of

Answer 26

conjugants

Question 27

To map genes of a bacterial strain, conjugation must be interrupted at given times. Suppose you have Hfr cells of genotype a+b+c+d+e+strR and F= cells of genotype a-b-c-d-e-strS and you combine these two cultures in liquid medium in four blenders at time 0. After intervals of 3, 6, 9, and 12 minutes, you turn on successive blenders. The resulting cultures were then plated on medium containing streptomycin. Why? to eliminate --

Answer 27

non-conjugated F- cells

Question 28

Conjugation between an Hfr cell and an F− cell does not usually result in conversion of exconjugants to the donor state. Occasionally however, the result of this conjugation is two Hfr cells. Transfer of the -- of the Hfr cell and recombination of the entire F plasmid DNA sequence into the recipient chromosome could convert an F− cell into an Hfr cell.

Answer 28

entire chromosome

Question 29

only -- involves the transfer of DNA from an Hfr cell to an F- cell

Answer 29

conjugation

Question 30

T/F: conjugation, transduction, and transformation can be used to map the order of genes on a bacterial chromosome

Answer 30

true

Question 31

T/F: Bacteria can acquire antibiotic resistance by a variety of methods, including random mutation and genetic transfer by transformation, transduction, or conjugation.

Answer 31

true

Question 32

A -- cotransduction frequency indicates that two loci are close together and thus more likely to move as a unit to the recipient cell

Answer 32

large

Question 33

Bacteriophages bind the bacteria host cell and inject their DNA into the host cell. The phage then --, which prevents its degradation.

Answer 33

circularizes

Question 34

In the -- cycle, new bacteriophages are made and the host cell is lysed.

Answer 34

lytic

Question 35

In the -- cycle, the phage DNA integrates into the host cell chromosome, and the phage DNA is replicated with the bacterial cell DNA as the cell divides.

Answer 35

lysogenic

Question 36

In which cycle is phage DNA transcribed and translated to make new phage particles (phage DNA is packaged into phage heads)?

Answer 36

lytic

Question 37

During transduction, fragments of bacterial DNA are -- packaged into the phage head.

Answer 37

randomly

Question 38

During transduction, phages package fragments of bacterial DNA into new --. This bacterial DNA can be transferred to another bacteria cell during the next phage infection.

Answer 38

phage heads

Question 39

In generalized transduction, a phage introduces a segment of donor DNA into the recipient cell. This is followed by recombination of the donor fragment with the recipient chromosome. Then, a -- of crossovers between the donor segment and the recipient

Answer 39

pair (or even number)

Question 40

a population -- if its genotype frequencies differ from those predicted by the Hardy-Weinberg principle.

Answer 40

may be evolving

Question 41

assuming random mating, each gamete's chance of carrying an allele equals --

Answer 41

that allele frequency

Question 42

square root method can only be used when the population is in -- and the two alleles in question exhibit a dominant and recessive relationship.

Answer 42

Hardy-Weinberg equilibrium