Deck 9: Gene Transfer, Mutations, and Genome Evolution

Question 1

Restriction enzymes are categorized into three types based on all of the following EXCEPT:

A) the number of subunits in the enzyme
B) the phages that are susceptible to their activity
C) the cofactors required for activity
D) where the DNA cleavage sites are located
E) whether the enzyme methylates the host DNA

Answer 1

B

Question 2

F factor contains how many origins of replication?

A) one
B) two
C) three
D) four
E) none

Answer 2

B

Question 3

The transfer of F factor in E. coli from one donor cell to a __________ cell results in two __________ cells.

A) donor; donor
B) recipient; recipient
C) donor; recipient
D) recipient; donor
E) recipient; Hfr

Answer 3

D

Question 4

__________ plasmids usually contain an oriT-like DNA replication origin that is recognized by the conjugation apparatus of the transferable plasmid.

A) Mobilizable
B) Fertility
C) Hfr
D) F'
E) Conjugative

Question 5

Bacteria have developed a "safe-sex" approach to gene exchange called __________ and __________.

A) conjugation; recombination
B) transformation; transposition
C) restriction; modification
D) transduction; Hfr
E) mobilizable; F plasmid

Question 6

A derivative F plasmid that contains host DNA is called an:

A) F plasmid
B) F⁺ plasmid
C) F^- plasmid
D) F' plasmid
E) Hfr plasmid

Question 7

The process in which bacteriophages carry host DNA from one cell to another is known as __________.

A) conjugation
B) transformation
C) transposition
D) recombination
E) transduction

Question 8

Because the F plasmid can exist in extrachromosomal and integrated forms, it is sometimes called a/an __________.

A) episome
B) F'
C) Hfr
D) lysogen
E) tranducing phage

Question 9

A special sigma factor, __________, is used to transcribe genes encoding the translocasome necessary for cell competency.

A) SigH
B) Sig70
C) SigT
D) SigC
E) Sig20

Question 10

Approximately how long does it take for an Hfr strain to transfer its entire chromosome?

A) 30 minutes
B) 60 minutes
C) 100 minutes
D) 180 minutes
E) 300 minutes

Question 11

Some conjugation systems use __________ to stimulate transfer of genetic information.

A) transformation
B) pheromones
C) transduction
D) transposition
E) reversion

Question 12

In __________ the number of genes transferred is limited by the size of the phage head.

A) transformation
B) conjugation
C) general recombination
D) specialized transduction
E) transposition

Question 13

The 5'-end of the nicked strand of F factor moves through a pore in the conjugation complex by a process driven by __________, which synthesizes a replacement strand in the donor cell using the intact strand as template.

A) DNA pol I
B) DNA pol II
C) DNA pol III
D) ligase
E) Hfr

Question 14

Interrupted mating involves breaking __________ bridges using a blender.

A) transformation
B) transduction
C) conjugation
D) transposition
E) bacteriophage

Question 15

Salmonella can conduct interspecies __________ with E. coli.

A) transduction
B) transformation
C) transposition
D) conjugation
E) recombination

Question 16

Which of the following bacteria requires artificial assistance to become competent to take up DNA?

A) Bacillus
B) E. coli
C) Haemophilus
D) Neisseria
E) Streptococcus

Question 17

During conjugation the DNA passes through the __________, NOT the __________.

A) membranes; pilus
B) pilus; membranes
C) pilus; phage
D) phage; pilus
E) F factor; phage

Question 18

Genes other than gal or bio can also be moved by __________ if lambda is used to infect mutant host strains lacking the normal att site.

A) specialized transduction
B) DNA polymerase
C) generalized transduction
D) transformation
E) conjugaton

Question 19

The recipient of Hfr conjugation __________ becomes an F⁺ or Hfr cell.

A) rarely
B) usually
C) always
D) never
E) frequently

Question 20

The process of importing free DNA into cells is known as __________.

A) tranposition
B) conjugation
C) specialized transduction
D) generalized transduction
E) transformation

Question 21

Large regions of sequence homology are required when recombining DNA molecules by __________ recombination.

A) general
B) site-specific
C) specialized
D) transposition
E) reversion

Question 22

A __________ colony is the result of a high mutation rate.

A) colored
B) wrinkled
C) large
D) sectored
E) convex

Question 23

Deinococcus chromosomal DNA is __________ by irradiation.

A) destroyed
B) fragmented
C) activated
D) mutated
E) recombined

Question 24

Which of the following is the activator of the SOS response?

A) RecA
B) LexA
C) FtsZ
D) sulA
E) uvrA

Question 25

Knockout mutations can include __________ mutations and __________ mutations.

A) gain of function; loss of function
B) gain of function; missense
C) frameshift; nonsense
D) silent; nonsense
E) silent; missense

Question 26

Newly replicated, and consequently __________, DNA sequences are invisible to a restriction enzyme.

A) mutated
B) restricted
C) modified
D) hemimethylated
E) single-stranded

Question 27

Ames used his reversion test with Salmonella to screen compounds for potential __________.

A) virulence
B) pathogenicity
C) toxicity
D) antibiotics
E) mutagenicity

Question 28

Numerous human genetic diseases are caused by mutations in homologs of bacterial:

A) transposons
B) ligases
C) integrases
D) polymerases
E) repair genes

Question 29

Which of the following forms of DNA repair is error-prone?

A) SOS repair
B) methyl mismatch
C) base excision
D) nucleotide excision
E) photoreactivation

Question 30

Mutations that occur even in the absence of a mutagen are known as __________ mutations.

A) spontaneous
B) silent
C) missense
D) nonsense
E) frameshift

Question 31

A synonymous substitution is a/an:

A) inversion
B) deletion
C) silent mutation
D) insertion
E) missense mutation

Question 32

The spontaneous mutation rate per generation occurs at which frequency indicated below?

A) 10^-2
B) 10^-3
C) 10^-5
D) 10^-7
E) 10^-9

Question 33

Which of the following is NOT true of a pyrimidine dimer?

A) It can be repaired by photoreactivation.
B) The pyrimidines are base paired one to another.
C) It is produced by ultraviolet light.
D) It blocks DNA replication.
E) It blocks transcription.

Question 34

Which of the following requires no homology between donor and recipient DNA molecules?

A) phage integration
B) phase variation
C) D-loop formation
D) transposition
E) integron capture

Question 35

A missense mutation may generate:

A) no phenotypic change
B) a loss-of-function mutation
C) a gain-of-function mutation
D) B and C
E) all of the above

Question 36

Which of the following mutagens may cause frameshift mutations?

A) caffeine
B) 5-bromouracil
C) nitrosoguanidine
D) nitrites
E) acridine dyes

Question 37

Why is recombination advantageous?

A) It allows cells to use DNA donated by others of the same species to repair their damaged genes.
B) It gives the ability to enhance the competitive fitness of the cell.
C) It is an internal method of DNA repair.
D) A and B
E) all of the above

Question 38

After extensive DNA damage, special DNA polymerases are expressed that sacrifice replication __________ to rescue the damaged genome.

A) accuracy
B) initiation
C) termination
D) modification
E) restriction

Question 39

__________ is the process of moving a transposable element within or between DNA molecules.

A) Transposition
B) Transduction
C) Transformation
D) Conjugation
E) Reversion

Question 40

RecA molecules are also called __________ because they are able to scan DNA molecules for homology and align the homologous regions, forming a triplex DNA molecule.

A) recombinases
B) integrases
C) polymerses
D) synaptases
E) transposases

Question 41

Is an Hfr cell also considered to be F⁺? Why or why not?

Question 42

Which of the following forms of transposition specifically describes the transfer of DNA from one cell to another?

A) nonreplicative
B) replicative
C) composite
D) complex
E) conjugative

Question 43

__________ are designed to spread when a population is facing danger.

A) F plasmids
B) Bacteriophage
C) Resistance plasmids
D) Conjugative transposons
E) Integrases

Question 44

Which of the following genes belongs to the so-called flexible gene pool?

A) ribosome
B) cell envelope
C) antibiotic resistance
D) DNA replication
E) metabolic pathways

Question 45

How do bacterial cells protect themselves from invading foreign DNA? Why aren't the bacteria harmed by this process?

Question 46

Why does a genetic experiment generally involve screening hundreds of millions of cells to find a few recombinants that form visible colonies?

Question 47

Describe several informational classes of mutations.

Question 48

Approximately what percent of the genome of E. coli O157:H7, which has been responsible for several outbreaks of foodborne disease, has been acquired from other species?

A) 5
B) 10
C) 25
D) 40
E) 50

Question 49

Why is genetic recombination advantageous to an organism?

Question 50

There are at least three classes of integrons based on the type of __________ gene they possess.

A) transposase
B) polymerase
C) integrase
D) exchange
E) attachment

Question 51

Name two traits that have been genetically engineered into plants. How were genes for these activities incorporated into the plant genome? Why is this method more advantageous than typical plant-breeding?

Question 52

Within a/an __________, the antibiotic cassettes can be shuffled in their position by excision and reintegration.

A) integrase
B) pathogenicity island
C) integron
D) F plasmid
E) Hfr

Question 53

Approximately what percent of the 4,288 open reading frames of E. coli have no known or annotated function?

A) 10
B) 14
C) 28
D) 52
E) 70

Question 54

Evolution toward pathogenicity may involve:

A) horizontal gene transfer
B) gene loss
C) gene acquisition
D) A and C
E) all of the above

Question 55

Define what it means for genes to be cotransduced. What does it tell you about the location of these genes and why?

Question 56

Site-specific recombination is RecA independent and requires very short regions of homology between donor and target DNA. Describe an example in either E. coli or Salmonella.

Question 57

Describe the differences in the transformation process in Gram-positive and Gram-negative organisms.

Question 58

The level of recombination between species is estimated to be about how many times greater than the mutation rate?

A) 10
B) 20
C) 50
D) 100
E) 1,000

Question 59

Phages that carry host DNA are called transducing particles. Describe how the Salmonella P22 phage accidentally packages host DNA.

Question 60

Which of the following is evidence of gene reduction?

A) altered GC content
B) different codon usage
C) pseudogenes
D) all of the above
E) none of the above

Question 61

Describe a frameshift mutation in terms of insertions and deletions. Does an insertion always result in a frameshift mutation? Will an insertion always render the gene product nonfunctional?

Question 62

Define a pseudogene and what it is thought to represent.

Question 63

Why did Ames modify the test to incorporate treatment of the potential mutagen with rat liver extract?

Question 64

Describe several error-proof DNA repair mechanisms.

Question 65

How is the Ames reversion test performed and what is it used to determine?

Question 66

What are the differences between replicative and nonreplicative transposition?

Question 67

Why is SOS repair considered to be an error prone repair mechanism? Why would an organism use an error prone mechanism?

Question 68

What is a pan-genome and why does this appear to be the best way to describe a species?

Question 69

What is transcription-coupled repair and why is it important for the cell?

Question 70

When a nonpermissive strain of Salmonella was infected with a P22 phage carrying a tetracycline resistance gene, the Salmonella still became resistant at a high frequency. How did this happen and what suggested this was the case?