Deck 10: Genetics of Bacteria and Arachaea

Question 1

Transformation and homologous recombination allow for the formation of heteroduplex DNA. Which of the following would occur during DNA replication of this molecule?

A) One daughter strand is complementary to the recombinant DNA molecule, while the other daughter strand is complementary to the parent DNA molecule.
B) Both daughter strands are complementary to the parent DNA molecule.
C) Both daughter strands are complementary to the recombinant DNA molecule.
D) None of the above is correct.

Answer 1

A

Question 2

F- strains of Escherichia coli

A) transfer the F factor to other strains at a high frequency.
B) have an integrated F factor.
C) have the F factor as a plasmid.
D) do not have an F factor.

Answer 2

D

Question 3

Drug resistance among enteric bacteria is spread rapidly by

A) conjugative plasmids.
B) selection of mutants.
C) bacteriophages.
D) selective transmission.

Answer 3

A

Question 4

Which of the following is most similar to lysogeny?

A) Hfr state
B) F+ state
C) F' state
D) F- state

Question 5

Consider conjugation in Escherichia coli. In which of the following matings would chromosomal genes be transferred most frequently?

A) Hfr × F-
B) F+ × F-
C) F- × F-
D) Hfr × F+

Question 6

The minimal amount of genetic information required for specialized transduction would include

A) the cos site.
B) a helper phage.
C) the att region.
D) all of the above.

Question 7

Ionizing radiation does NOT include

A) gamma rays.
B) UV rays.
C) cosmic rays.
D) X- rays.

Question 8

Hfr strains of Escherichia coli

A) have an integrated F factor.
B) do not possess an F factor.
C) have the F factor as a plasmid.
D) transfer the complete F factor to recipient cells at a high frequency.

Question 9

Genetic recombination involving insertion sequences typically results in what type of mutation?

A) missense mutation
B) frameshift mutation
C) silent mutation
D) base- pair substitution mutation

Question 10

All Hfr strains integrate into the chromosome at

A) the same locus.
B) several specific sites.
C) loci that cannot be accurately determined.
D) the same locus most of the time, although there may be some variation.

Question 11

A mutant that has a nutritional requirement for growth is an example of a(n)

A) organotroph.
B) auxotroph.
C) autotroph.
D) heterotroph.

Question 12

Which is a phenotype of an F- cell?

A) The chromosomal DNA can be transferred to another cell.
B) The cell can take up DNA from an F- containing donor cell.
C) The cell can participate as a donor in conjugation.
D) The cell can synthesize an F pilus.

Question 13

In the bacterial world, a gene located on which of the following would be the LEAST likely to be transferred?

A) the chromosome
B) R factor
C) the phage Mu
D) F⁺

Question 14

Transposition is a(n)

A) site- specific recombination event.
B) general recombination event.
C) homologous recombination event.
D) analogous recombination event.

Question 15

A transducing particle is produced during the type of genetic recombination known as

A) conjugation.
B) transformation.
C) specialized transduction.
D) generalized transduction.

Question 16

Plasmids that govern their own transfer are known as

A) transmutable.
B) conjugative.
C) transfective.
D) transformable.

Question 17

Which of the following methods may introduce foreign DNA into a recipient?

A) transduction
B) conjugation
C) transformation
D) all of the above

Question 18

A "point mutation" refers to mutations involving

A) a base- pair substitution.
B) the deletion of a base pair (microdeletion).
C) the gain of a base pair (microinsertion).
D) any of the above.

Question 19

A plasmid may

A) be integrated into the chromosome.
B) replicate independently of the chromosome.
C) be transferred cell to cell during conjugation.
D) be involved in any of the above.

Question 20

A strain of an organism with an increased mutation rate is known as a(n)

A) encoded dnaQ system.
B) adaptive mutagen strain.
C) phenotypic variation.
D) hypermutable or mutator strain.

Question 21

Homologous recombination has been observed in

A) Bacteria.
B) Eukarya.
C) Archaea.
D) all of the above.

Question 22

Which of the following features are common to transformation, transduction, and conjugation? 1() unidirectional transfer of genes
2() incomplete gene transfer
3() homologous recombination
4() meiosis occurring in the recipient

A) 1, 2, 4
B) 1, 2, 3
C) 3, 4
D) 1, 2

Question 23

Which of the following would NOT be a trait of a resistance plasmid?

A) It may carry heavy metal resistance genes.
B) It may carry antibiotic resistance genes.
C) It increases the host's growth rate.
D) It may undergo genetic recombination.

Question 24

The positions of genes on a genetic map are marked according to

A) degrees.
B) radians.
C) minutes.
D) nanometers.

Question 25

The SOS regulatory system is activated by

A) transcription of LexA.
B) repression of RecA.
C) DNA damage.
D) the activity of DNA polymerase IV.

Question 26

The killing of cells by UV irradiation involves

A) formation of purine dimers.
B) absorption at 260 nm by RNA only.
C) formation of pyrimidine dimers.
D) absorption at 260 nm by proteins only.

Question 27

Which of the following proteins is NOT required for homologous recombination?

A) RecA
B) proteins having helicase activity
C) endonuclease
D) Hfr

Question 28

Consider a mutation in which the change is from UAC to UAU. Both codons specify the amino acid tyrosine. Which type of point mutation is this?

A) frameshift mutation
B) missense mutation
C) silent mutation
D) nonsense mutation

Question 29

You have performed the following mating experiment using Hfr and F- strains of Escherichia coli: Hfr (thr+ leu+ gal+ strs) × F- (thr- leu- gal- strr). Which of the following selective media would you use to score recombinant colonies?

A) minimal medium + streptomycin
B) minimal medium + appropriate nutrient
C) minimal medium + streptomycin + appropriate nutrient
D) minimal medium

Question 30

A mutation in recA results in

A) a decrease in specific recombination.
B) an increase in homologous recombination.
C) a decrease in homologous recombination.
D) no change in either general or specific recombination.

Question 31

Frederick Griffith's experiments, which showed that the R strain was able to pick up DNA from a heat- treated S strain of Streptococcus pneumonia, provided the first evidence of

A) homologous recombination.
B) transformation.
C) transduction.
D) conjugation.

Question 32

F+ strains of Escherichia coli

A) have the F factor as a plasmid.
B) have an integrated F factor.
C) do not have an F factor.
D) transfer the F factor to recipient cells at a high frequency.

Question 33

Which process involves the formation of Holliday junctions?

A) transformation
B) transduction
C) homologous recombination
D) conjugation

Question 34

Consider the following experiment. First, large populations of two mutant strains of Escherichia coli are mixed, each requiring a different, single amino acid. After plating them onto a minimal medium, 45 colonies grew. Which of the following may explain this result?

A) The colonies may be due to recombination.
B) The colonies may be due to back mutation (reversion).
C) Either A or B is possible.
D) Neither A nor B is possible.

Question 35

The production of a functional gene product by transforming bacteria that lack a lacZ gene with a plasmid containing a lacZ gene is known as

A) trans complementation.
B) cis complementation.
C) transfection.
D) conjugation.

Question 36

A mutation that readily reverses to restore the original parental type would most likely be due to a(n)

A) frameshift mutation.
B) point mutation.
C) deletion.
D) insertion.

Question 37

Lysogeny probably carries a strong selective advantage for the host cell because

A) it confers resistance to infection by viruses of the same type.
B) it prevents cell lysis.
C) it confers resistance to infection by viruses of a different type (or strain).
D) of all of the above.

Question 38

The enzyme transposase may be coded for by (the)

A) IS on a chromosome.
B) IS on a plasmid.
C) IS on a phage.
D) all of the above.

Question 39

The mutagens 2- aminopurine and 5- bromouracil are examples of

A) alkylating agents.
B) chemicals reacting with DNA.
C) nucleotide base analogs.
D) none of the above.

Question 40

The uptake of DNA released from a cell would most likely be the result of _ , while cell- to- cell contact would most likely result in .

A) transduction / conjugation
B) transformation / transduction
C) conjugation / transformation
D) transformation / conjugation

Question 41

A cellular mechanism, known as the , is activated because of DNA damage and initiates a number of DNA repair processes.

Question 42

All Hfr strains possess an F factor integrated into the host chromosome.

Question 43

when a bacterium's phenotype changes as the result of a(n) into its genome.

Question 44

A(n) is a set of genes or operons that are all under the control of a particular type of _ .

Question 45

is a specific type of transformation where bacteriophage DNA is taken up by bacterial cells.

Question 46

Microinsertions and microdeletions often result in mutations.

Question 47

The F (fertility) plasmid contains a set of genes that encode for the proteins that are essential in conjugative transfer of DNA.

Question 48

Called "crossing over" in classical genetics, the process in which DNA sequences are exchanged is now more commonly termed .

Question 49

The IS element cannot code for the transposase enzyme.

Question 50

The appropriate designation for the phenotype of a histidine- requiring strain of Escherichia coli would be .

Question 51

A mutation that replaces a pyrimidine with another pyrimidine or a purine with another purine is called a(n) _ , and a(n) is a mutation of a purine to a pyrimidine or a pyrimidine to a purine.

Question 52

Hfr means , and these cells are capable of transferring genes from their .

Question 53

One method of determining the order in which genes are present on an Hfr donor is to perform a kinetics experiment involving of conjugating cells.

Question 54

A bacterium containing two copies of a chromosomal nucleotide sequence is called a(n)
. Typically one copy is present on the _ and the other on a(n) .

Question 55

The two primary mechanisms of transposition are _ _ and .

Question 56

In generalized transduction, virtually any genetic marker can be transferred from donor to recipient at a high frequency. This process may occur with either a temperate or a virulent phage.

Question 57

If a bacterium carrying a plasmid that confers resistance to ampicillin is placed into medium without ampicillin, the loss of the plasmid is a phenomenon known as _.

Question 58

The designations Phe- , Leu- , and Ser+ refer to an organism's _.

Question 59

Almost all plasmids are double- stranded DNA.

Question 60

Bacterial mating (or conjugation) is a bidirectional process where nucleic acids (DNA or RNA) are transferred during a cell- to- cell interaction involving a donor and a recipient cell.

Question 61

Intercalating agents, like acridine orange and ethidium bromide, lead to mutagenesis by pushing DNA base pairs apart, which can lead to insertions or deletions.

Question 62

The use of transposons to generate mutations is a convenient way to create bacterial mutations in the laboratory.

Question 63

When the F factor is integrated, all Hfr strains have the origin of replication functioning in the same direction.

Question 64

The F plasmid of Escherichia coli is about 99 kbp and is present in both F+ and F- strains.

Question 65

Proteins and nucleic acids absorb light maximally at 260 nm; hence, proteins protect cells from UV effects.

Question 66

Penicillin selection is a positive selection for the isolation of mutants with growth factor requirements.

Question 67

Archaea contain a conjugation mechanisms similar to Bacteria, but they also have a unique form involving cytoplasmic bridges for bidirectional transfer of DNA.

Question 68

A typical mutation rate for a bacterium is in the range of 10- 6 to 10- 9 per kbp.

Question 69

It is likely that lysogeny has a selective advantage in nature.

Question 70

ISs do not encode for known phenotypic traits and are smaller than either Tn or Mu.

Question 71

Most plasmids are circular rather than linear.

Question 72

Of the transposons that are now widely used, Tn5 and Tn10 carry antibiotic resistance markers to select for mutants.

Question 73

In specialized transduction, as exemplified in the lambda- Gal system, transduction by a lysate occurs at high efficiency for only a restricted group of gal genes, and induction of a lysogenic cell is required.

Question 74

Following uptake, transforming DNA becomes attached to a competence- specific protein that prevents it from nuclease attack until it reaches the chromosome.

Question 75

The evolutionary significance of phage conversion likely stems from an effective alteration of host cells.

Question 76

Toxigenicity in Corynebacterium diphtheriae is due to phase conversion (lysogenization with fi
phage).

Question 77

UV radiation is a useful tool in producing mutants of microbial cultures.

Question 78

Many Bacteria isolated from nature are natural lysogens.

Question 79

When UV radiation damage occurs, DNA repair occurs only in the absence of template instruction.

Question 80

In transformation experiments using a variety of Bacteria, it has been noted that essentially all of the cells in a population can become competent.