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BIOL 2P98 > Ch 4/11: Bacterial Sex > Flashcards

Ch 4/11: Bacterial Sex Flashcards

1
Q

What is horizontal gene transfer

A

non-sexual movement of genetic information between genomes

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2
Q

What is vertical gene transfer

A

the transfer of genetic material is from parents to offspring

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3
Q

What is the shape of DNA is most bacteria

A

circular

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4
Q

What components of DNA in bacteria

A
  1. bidirectional replication
  2. replication fork
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5
Q

How many origins in the DNA are there in bacteria

A

single

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6
Q

What happens at the replication fork in bacterial dna

A

DNA is unwound

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7
Q

What is the replicon in bacterial DNA

A

the entire region of DNA that is independently replicated from a single origin of replication

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8
Q

What is the shape of the DNA in archaea

A

circular

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9
Q

How many origins does archaea have in DNA

A

more than one (possible)

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10
Q

What is the pattern of chromosome in eukaryotes

A

linear

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11
Q

How many replication forks can eukaryotes have

A

many

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12
Q

What is the typical shape of bacterial chromosome

A

circular

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13
Q

How many chromosomes can bacteria have

A

one typically.

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14
Q

Example of bacteria that have more than 1 chromosomes

A

Cholera-causing bacteria has 2

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15
Q

Does bacteria have a nucleus

A

no

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16
Q

what do bacteria have instead of a nucleus

A

Nuclear region or nucleoid

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17
Q

what long is the bacterial chromosome

A

1mm

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18
Q

What type of twisting happens in bacterial DNA

A

supercoiled

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19
Q

what are plasmids

A

small, extrachromosomal DNA molecules,
autonomously replicating.

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20
Q

How many different plasmids can bacterial cells carry

A

several different, with few to many copies

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21
Q

what is the effect of gene transfer among bacteria

A

spreads useful genes among bacteria

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22
Q

what types of useful genes does gene transfer spread

A

1.antibiotic resistant genes
2. pathogenicity islands
3. genes to degrade special metabolites (?)

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23
Q

Where do antibiotic resistance genes spread

A

wherever antibiotics are overused. Eg, hospitals and farms

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24
Q

Why do pathogenicity islands encode genes

A

for the cell to act as pathogen

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25
Q

What difference typical E.coli and pathogenic Ecoli cause illness

A

Typical E.coli is found in gut and is useful. And pathogenic E.coli is harmful

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26
Q

What are pathogenicity Islands

A

are distinct genetic elements on the chromosomes of a large number of bacterial pathogens

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27
Q

What are metabolites

A

a substance formed in or necessary for metabolism.

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28
Q

what are some examples metabolites that gene transfer can degrade

A

oil slicks

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29
Q

What are the methods of genetic exchange

A
  1. transformation
  2. Conjugation
  3. transduction
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30
Q

What is transformation method

A

The non-specific acceptance by a bacterial
cell of small fragments of DNA from
the surrounding environment.

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31
Q

What facilitates transformation method of DNA

A

special DNA-binding proteins
on the cell wall that capture DNA

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32
Q

What type of cells use the transformation method for gene exchange

A

competent cells

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33
Q

what are competent cells

A

microbial cells that can readily take up foreign DNA from their surroundings through a process called transformation

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34
Q

When DNA is captured in transformation method, what happens to the new DNA

A

its incorporated into the chromosome

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35
Q

mention some places where transformation can be very useful

A
  1. biotechnology
  2. recombinant DNA Technology
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36
Q

When growing bacteria what types of strains can the bacteria have

A
  1. R strain - Rough
  2. S Strain - Smooth
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37
Q

What is the R strain

A

It is benign

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38
Q

what is S strain

A

it is virulent

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39
Q

Is the R strain protected?

A

No. It lacks a protective capsule

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40
Q

Is the S strain protected

A

Yes by a polysaccharide

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41
Q

What is the significance of having or not having a protective layer in S strain and R strain

A

R Strain: no protection = get recognized and destroyed by hosts immune system

S Strain: yes protection = prevents detection by hosts immune system

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42
Q

What is the capsule

A

Capsule is a gel-like
Covering made chiefly
of polysaccharides.

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43
Q

what is the capsule associated with

A

virulent

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44
Q

What does the capsule help resist

A

phagocytosis

45
Q

What is phagocytosis

A

important process for nutrition in unicellular organisms

46
Q

Is the capsule genetic?

A

Yes. Its genetically encoded

47
Q

what is conjugation

A

Transfer of DNA from one
bacterium to another by cellular contact

48
Q

In conjugation, what direction does the DNA move when moving from one bacteria to the other

A

DNA moves unidirectionally from one
bacterium (the donor), to another bacterium,
(the recipient).

49
Q

What states are the genes involved in genetic transfer exist in the donor

A
  1. On a F Plasmid
  2. On a F’ plasmid
  3. Integrated into bacterial chromosome Hfr
50
Q

What is bacterial chromosome Hfr

A

High frequency of recombination. A strain of bacteria that has incorporated an F factor into its chromosome and can then transfer the chromosome during conjugation

51
Q

Through what medium does conjugation occur in bacteria

A

through a cytoplasmic bridge

52
Q

What is F+ cell

A

the donor (of gene)

53
Q

What is the F- cell

A

the acceptor (of gene)

54
Q

What is the type IC secretion system

A

pilus (? – textb)

55
Q

for bacterial sex where are the pilus proteins encoded

A

on F Factor

56
Q

On what site does the pilus protein encoding start

A

oriT

57
Q

in bacterial sex, in the recipient cell, what does the transferred DNA form

A

forms a new plasmid

58
Q

After the bacterial sex, what happens to the “female” cells

A

they become “male” cells i.e. they’re able to transfer to DNA

59
Q

how many states do transfer genes exist in

A

3

60
Q

How many forms do genetic transfers occur in

A

3

61
Q

What are the forms in which genetic transfers occurs

A
  1. F+ —–> F-
  2. F’ ——> F-
  3. Hfr ——> F-
62
Q

What is the F+ donor

A

The donor “male” has a fertility factor (F+) that is itself heritable.

63
Q

What is the F’ donor

A
64
Q

What is the F Plasmid

A

fertility factor

65
Q

What is the structure of the F Plasmid

A

circular DNA molecule with one region that contains the genes that regulate DNA replication

66
Q

What is the large region of DNA in F Plasmid called

A

tra region

67
Q

What is the tra region

A

it contains genes that encode transfer functions

68
Q

What is the F’ Factor

A

its the fertility factor plasmid that contains extra genes (in addition to genes for pilus and transfer)

69
Q

What happens to the extra genes that F’ has

A

get transferred to recipient

70
Q

What is the Hfr plasmid

A

in Hfr the F factor integrates on the bacterial chromosomes

71
Q

What does the Hfr transfer to the recipient

A

tried to transfer the entire chromosome

72
Q

Can Hfr determine the order of genes on chromosome

A

yes

73
Q

Can Hfr transfer genes in order

A

yes

74
Q

What is the name of Hfr

A

high frequency of recombination

75
Q

In the production of F’ and Hfr, what region loops out of the chromosome

A

the F Factor loops out and takes a portion of the bacterial chromosome

76
Q

What does a single crossover generate

A

F’ which includes bacterial chromosome

77
Q

In terms of gene transfer, what are F plasmids responsible for

A

antibiotic resistance

78
Q

F plasmids that harbours genes for antibiotic resistance are called

A

R factors

79
Q

how many antibiotic resistance genes can a single F’ plasmid harbour

A

several

80
Q

Bacteria resistance to several antibiotics are called

A

MDRs or multidrug-resistant bacteria

81
Q

___ Plasmid can also carry genes encoding traits that play a role in disease

A

F’

82
Q

example of subtance that plays a role in disease whose gene F’ plasmid carries

A

toxins

83
Q

What are R Factors

A

F’ plasmids that contain both transfer tra genes and genes for antibiotic resistance

84
Q

Can MDR bacteria transfer the resistance during conjugation

A

yes!

85
Q

What happens in transduction

A

a bacterial virus (bacteriophage) transfers
DNA from one cell to another

86
Q

what is a bacterial virus called

A

bacteriophage

87
Q

viruses that inject their DNA into cell are called

A

bacteriophage

88
Q

bacteriophage pack DNA into viral ___

A

capsid

89
Q

Can the the bacteriophage package bacterial DNA by mistake

A

Yes

90
Q

in order for newly acquired DNA to be incorporated what is required

A

has to go through recombination

91
Q

What happens if the newly acquired dna doesn’t get incorporated

A

youll have very transient diploids

92
Q

What type of gene transfer is important for evolution

A

horizontal gene transfer

93
Q

are genes be transferred to the same specie or different species

A

both

94
Q

what are mutagens

A

Anything that causes a mutation (a change in the DNA of a cell)

95
Q

Most carcinogens are also ___

A

mutagens

96
Q

tests for mutagenicity are used as screen for ______ potential

A

carcinogenic

97
Q

What is an examples of an carcinogenic test

A

Ames test

98
Q

what are auxotrophs

A

a group of organisms that lost the ability to synthesize certain substances required for their growth owing to the presence of mutations

99
Q

what kind of strain does the ames test use

A

uses bacterial strain auxotrophic for histidine i.e cannot grow unless histidine is supplied

100
Q

What does it mean to be auxotrophic for something

A

the organism has a mutation in that thing and cant grow unless it is supplied with that thing

101
Q

On the plate medium for ames test, if the mutagen added to the plate causes reversion, what does it mean

A

reversion means that the auxotrophic mutagen changed to its normal form — this is a rare mutation

102
Q

on the plate medium for ames test, what does it mean if more colonies are grown

A

more colonies = stronger mutagen

103
Q

what does cancer result from

A

multiple mutations

104
Q

DNA transfer occurs typically in one direction, which is

A

donor to recipient

105
Q

3 mechanisms of horizontal gene transfer

A
  1. transformation
  2. transduction
  3. conjugation
106
Q

What some origins of replication

A
  1. a plamid
  2. phage genome
107
Q

what is meant by origin of replication

A

An origin of replication is a sequence of DNA at which replication is initiated on a chromosome, plasmid or virus.

108
Q

what are the 3 fates that horizontally transferred DNA can face

A
  1. it degrades by recipient restriction enzymes or dna destruction systems
  2. may replication by itself if it has origin of replication
  3. it may recombine with recipient cell chromomsome

BIOL 2P98 (8 decks)

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