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Microbio > Bacterial Genetics (#2) > Flashcards

Bacterial Genetics (#2) Flashcards

1
Q

the _______ is the location of the chrosome and associated proteins in bacteria

A

nuceloid

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2
Q

the nucleoid is an ________ shaped region, that is usually not _______ bound

A

irregularly; membrane

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3
Q

exception of bacteria where nucloids DO have a lipid bilayer/membrane around the chormosome

A

plantomyces (in 2 genera of family)

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4
Q

bacterial nucleoid genome:

A

usually one, circular, dsDNA molecule

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5
Q

bacterial nucloeids are tightly coiled, but have some _____ edges like a ball of yan

A

loose

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6
Q

what kind of cells have nuceloids in general?

A

prokaryotic cells

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7
Q

extra-chromosomal DNA

A

plasmids

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8
Q

plasmids usually have what kind of genome?

A

small, closed circular dsDNA

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9
Q

plasmids exist and replicate _________ of chromosome; own replication functions

A

independently

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10
Q

T/F: plasmids double every time the cell divides and is split up evenly between the cells

A

false (uneven inheritance/division can occur)

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11
Q

plasmids contain few _____

A

genes

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12
Q

the few genes that plasmids do contain are __________ and ____________ genes

A

non-essential; housekeeping genes

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13
Q

the non-essential genes that plasmids contain could be selectively ________

A

advantageous (like a bag of goodies)

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14
Q

plasmids are a lot ______ than chromosomes

A

smaller

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15
Q

plasmids increase _______ of a bacteria/organism

A

diversity

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16
Q

T/F: bacteria can’t survive without plasmids

A

false (they can, but plasmids can be advantageous)

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17
Q

plasmids can be _________ (make lots of copies) or _________

A

high-copy # or low-copy #

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18
Q

plasmids can be easily _____ if cells don’t use it are are less _____ than traits found on chromosomes

A

lost; stable

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19
Q

plasmids that CAN incorporate onto the chromosome so they don’t get lsot

A

episomes

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20
Q

example of advantages bacteria can acquire from plasmids (2):

A
  • antibiotic resistance
  • have lactase — use lactose as a carbon source
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21
Q

DNA is composed of 4 ______ , or _______

A

nucleotides; bases

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22
Q

who came up with the fact that DNA is the genetic material (3)?

A
  • Griffith
  • Avery, MacLeod, and McCarthy
  • Hershey and Chase
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23
Q

came up with Transforming Principle; smooth (had capsule) vs rough cell experiment

A

Griffith

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24
Q

disocovered that bacteriophage T2’s genome was DNA

A

Hershey and Chase

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25
Q

who discovered the STRUCTURE of DNA?

A

Watson and Crick

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26
Q

DNA is composed of _____ base pairs, with ________ strands

A

nitrogenous; antiparallel

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27
Q

DNA segment that codes for a polypeptide, rRNA, or tRNA

A

gene

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28
Q

when writing out genes, they are ________ and _________

A

lowercase + italicised (ex: hisC)

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29
Q

specific set of genes an organism possesses (the nucleotide sequence)

A

genotype

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30
Q

set of OBSERVABLE characteristics

A

phenotype (p for picture)

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31
Q

when writing out phenotypes, you use what?

A

+ or - signs (His+ or His-)

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32
Q

strain isolated from nature; considered “non-mutant” form

A

wild-type strain

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33
Q

stable, heritable change in nucleotide sequence; genotype is altered; may or may not have an effect on the phenotype of an organism

A

mutation

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34
Q

mutation that doesn’t alter the phenotype; goes unnoticed

A

silent mutation

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35
Q

how do you write out mutations?

A

italicized, designation of gene + order of mutation (hisC1, hisC2, etc)

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36
Q

types of mutations (2):

A
  • forward
  • reverse
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37
Q

most prevalent form of a gene

A

wild-type

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38
Q

type of mutation: wild-type to mutant form

A

forward mutation

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39
Q

example of forward mutation:

A

prototroph —> auxotroph

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40
Q

nutritional mutant

A

auxotroph

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41
Q

type of mutation: mutant PHENOTYPE to wild-type PHENOTYPE

A

reverse mutation

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42
Q

example of reverse mutation:

A

auxotroph –> prototroph

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43
Q

products of reverse mutatations =

A

revertants

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44
Q

ways to get revertants (2):

A
  • same-site revertants
  • second-site revertants
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45
Q

way to get revertant: base pairs that changed are changed back to its ORIGINAL (ex: A-T to C-G back to A-T)

A

same-site revertant

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46
Q

way to get revertant: suppressor mutation; still have mutations, but composited with another mutation somewhere else; changes it back to original wild-type phenotype

A

second-site revertant

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47
Q

non-nutritional mutant

A

prototroph

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48
Q

detecting mutants via observation

A

screening

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49
Q

mutations that confer some type of advantage to the organisms that possess them (ex: drug resistance)

A

selectable mutations

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50
Q

selectable mutations _______ screening time

A

decrease

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51
Q

placing organisms under conditions where the growth of those with a particular GENOTYPE will be favored; only allows MUTANTS to grow

A

selection

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52
Q

detection of nutritional auxotrophs (2):

A

1) pick and transfer colonies to fresh medium (complete + selective)
2) incubate and examine plates

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53
Q

2 type of mediums

A
  • complete
  • selective
54
Q

type of medium: ALL colonies grow

A

complete

55
Q

type of medium: mutants to NOT grow; missing growth factor (ex: histodine) that auxotrophic mutants need to grow

A

selective

56
Q

looking at what did NOT grow on the selective medium

A

negative selection

57
Q

missing colonies are _________ _________; look back at complete medium to use them

A

histodine auxotrophs

58
Q

______ _____ procedure may also be used to detect nutritional auxotrophs

A

replica plating

59
Q

HGT =

A

horizontal gene transfer

60
Q

________ can do horizontal gene transfer, but we can’t

A

bacteria

61
Q

horizontal gene transfer increase _______ quickly; allows bacteria to adapt faster

A

diversity

62
Q

3 methods of HGT:

A

1) transformation
2) transduction
3) conjugation

63
Q

method of HGT: donor DNA from a dead cell (naked DNA outside of the cell) to a recipient cell which then expresses it

A

transformation

64
Q

what kind of DNA is transformed in transformation?

A

naked DNA (outside of the cell)

65
Q

method of HGT: virus makes a mistake and packages DNA from its original host cell and releases it to another bacterium; transfer BACTERIAL DNA, not viral

A

transduction

66
Q

method of HGT: a donor cell that can make a sex pilus that attaches to recipient cell; sends a copy of a PLASMID to contains the traits for this method

A

conjucation

67
Q

plasmid used in conjugation

A

fertility plasmid (F plasmid)

68
Q

there are cases where ______ transfer occurs along with plasmid transfer in conjugation

A

chromosome

69
Q

T/F: horizontal gene transfer always works

A

false

70
Q

fates of donor DNA during horizontal gene transfer

A
  • host restriction
  • donor DNA self-replicates (ex: plasmid)
  • donor DNA self-replicates
  • integration of donor DNA
71
Q

fate of donor DNA during HCG: restriction endonucelase cuts up foreign DNA and then cell reproduces with NO stable recombinants

A

host restriction

72
Q

enzyme that cuts up foreign DNA; can be advantageous to cut up viral DNA; specific where it cuts at; prevents cells from being infected with bad DNA

A

restriction endonuclease

73
Q

fate of donor DNA during HCG: donor DNA just hangs out and eventually gets lost in a daughter cell; recipient reproduces but donor DNA does not – NO stable recombinants

A

Donor DNA cannot self-replicate

74
Q

fate of donor DNA during HCG: forms a plasmid and reproduces; produces population of STABLE recombinants (traits can be expressed)

A

Donor DNA self-replicates

75
Q

fate of donor DNA during HCG: DNA goes onto the chromosome; chromosome replicates with DNA; produces a population of STABLE recombinants

A

Integration of donor DNA

76
Q

one or more nucleic acid molecules are rearranged or combined to produce a NEW nucleotide sequence

A

genetic recombination

77
Q

types of recombination (2):

A
  • homologous
  • heterologous
78
Q

type of recombination: usually involves a reciprocal exchange between a pair of DNA molecules with the SAME (or nearly the same) nucleotide sequence; one type

A

homologous recombination

79
Q

recombination leads to new ______

A

genes

80
Q

in homologous recombination, DNA strands break and reunite leading to a _________

A

“crossover”

81
Q

steps of homologous recombination (4):

A

1) DNA strand is nicked
2) SSB protein and RecA protein complex formed
3) recipient DNA invaded
4) crossover leads to exchange which is then ligated to form two recombinant DNA molecules

82
Q

for homologous recombination to occur, bacteria has to be _______ positive (have this protein)

A

RecA+

83
Q

protein that pulls foreign DNA into double helix (like a train); if enough base pairs match, strands will try to bond (brakes on train) and ends in homo. recombination

A

RecA+

84
Q

number of matching base pairs between recipient and foreign DNA in LOW LEVEL recombination

A

20-40 matching base pairs

85
Q

number of matching base pairs between recipient and foreign DNA required in HIGH LEVEL recombination

A

> 165 pairs

86
Q

enzyme that determines which way crossing over occurs

A

resolvase

87
Q

protein that binds to single strand of DNA and protects it from being cut up further

A

SSB (single strand binding protein)

88
Q

Trp- cells dont make _______ on their own

A

tryptophan

89
Q

if Trp- cell are incoluated onto agar medium lacking tryptophan, what happens?

A

no growth

90
Q

if DNA from Trp+ cells are introduced to Trp- cells and incoluated onto agar medium lacking tryptophan, what happens?

A

recombinants form colonies

91
Q

uptake of naked DNA by a competent cell followed by incorportation of the DNA into the recipient cell’s genome

A

transformation

92
Q

transformation can be _______ or _______

A

natural or artificial

93
Q

transformation can also occur with a ________

A

plasmid

94
Q

how is transformation induced artificially (2)?

A
  • heat shock
  • electroporation (uses jolts of electricity)
95
Q

cell that can bind to DNA and bring it into the cell

A

competent cell

96
Q

competence can alter based on __________ and _________; my not be for long

A

species + environment

97
Q

the DNA incorporated into the recipient cell’s genome during transformation much be able to ________

A

replicate

98
Q

transfer of DNA from one cell to another by a BACTERIOPHAGE; mistake phage makes

A

transduction

99
Q

2 mods of transduction:

A

1) generalized transduction
2) specialized transduction

100
Q

mode of transduction: DNA from any portion of the host genome is packaged inside the virion

A

generalized transduction

101
Q

mode of transduction: DNA from a SPECIFIC region of the host chromosome is integrated directly into the virus genome

A

specialized transduction

102
Q

generalized transduction only occur during which cycle?

A

lytic cycle

103
Q

during viral assembly in generalized transduction, fragment of host DNA are mistakenly packaged into the phage HEAD, called the _____ _________

A

transducing particle

104
Q

the transducing particle in generalized transduction is _________

A

defective (virus cannot cause a normal viral infection anymore)

105
Q

cuts genome to correct size for virions during generalized transduction; bacterial DNA then gets into virus

A

cackatomer

106
Q

the transducing PARTICLE contains what kind of DNA?

A

donor cell DNA (bacterial)

107
Q

the transduced recipient cell contains what kind of DNA?

A

viral DNA

108
Q

mode of transduction: carried out by temperate phages that have established LYSOGENY; DNA incorporates itself on bacterial chromosome

A

specialized transduction

109
Q

specialized transduction occur when __________ is incorrectly excised

A

prophage

110
Q

steps of specialized transduction (4):

A

1) induction
2a) phage DNA circularizes and detaches from host DNA
2b) a portion of host DNA is exchanged for phage DNA (Rare Event)
3) detached DNA replicates
4) phage replication is completed and cell lyses

111
Q

during normal induction in transduction, a _______ comes off the chromosome and goes into the lytic cycle

A

prophage

112
Q

during the NORAML event in specialized transduction, the phage DNA circularized and detaches from host DNA using __________

A

exionase

113
Q

during the rare event in specialized transduction, a mistake is made during ___________ and exionase cuts out ________ genes and ______ genes

A

induction; galactose genes + adjacent genes

114
Q

during the rare event in specialized transduction, every single viral genome has ________ genes and are _______

A

galactose; defective

115
Q

all defective phages that carry galactose genes in specialized transduction

A

λdgal

116
Q

λdgal stands for

A

λ: lambda
d: defective
gal: carries galactose gene

117
Q

steps of bacterial conjugation (5):

A

1) the pilus retracts
2) cell pairs are stabilized; F plasmid nicked in one strand
3) transfer of one strand from F+ to F- cell; F plasmid simultaneously replicated in F+ cell
4) synthesis of complementary strand begins in the recipient cell
5) completion of DNA transfer and synthesis; cells separate

118
Q

genes for conjugation are usually found on _______

A

plasmids

119
Q

donor cell; carry plasmid

A

F+ cell

120
Q

recipient cell WITHOUT plasmid

A

F- cell

121
Q

region on plasmid that contains genes for conjugation

A

tra region

122
Q

what does “ori” mean on the F plasmid?

A

original of replication

123
Q

what does “IS3” mean on the F plasmid?

A

insertion sequence

124
Q

what does “Tn1000” mean on the F plasmid?

A

transposon

125
Q

2 origin of replications of F plasmid:

A
  • oriT
  • oriV
126
Q

origin of replication on F plasmid: origin of replication when it is going into the other cell for rolling circle replication; where you break plasmid to go into other cell; where DNA polymerase binds when conjugation occurs

A

oriT

127
Q

origin of replication on F plasmid: origin for vegetative plasmid; NORMAL origin of replication; where DNA polymerase would bind

A

oriV

128
Q

what does oriT stand for?

A

origin of TRANSFER

129
Q

when the single strand rolls up and is replicated to get a dsDNA plasmid in other cell during conjugation

A

rolling circle replication

130
Q

a ________ strand of DNA is transferred from the F+ to F- cell

A

single (sends a copy of a plasmid)

131
Q

T/F: F plasmids can carry other genes besides those for conjugation

A

true (ex: antibiotic resistance)

Microbio (21 decks)

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