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Microbiology Lecture Slides > Bacterial Genetics > Flashcards

Bacterial Genetics Flashcards

1
Q

Bacterial populations are clonal, meaning that in the absence of mutation or gene exchange, all descendants of a cell are

A

Genetically identical

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2
Q

Rare genetic events that have a substantial probability of occurrence

A

Corollary

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3
Q

In Neisseria gonorrhoeae, resistant mutations accumulate with the use of

A

Penicillin

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4
Q

What is the concentration of penicillin required to inhibit the growth of Neisseria gonorrhoea?

A

0.015 ug/mL

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5
Q

Bacteria can also acquire drug resistance from

A

Another source

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6
Q

Encodes an enzyme that hydrolyzes penicillin

A

Plasmid-based gene

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7
Q

Bacterial genomes are typically made up of a single

A

Circular DNA molecule

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8
Q

A few species of bacteria have

A

Multiple or linear chromosomes

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9
Q

Makes all required compounds from glucose, multiplies outside host

A

E. coli (4700 genes)

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10
Q

Obligate parasite, requires many small molecules for survival

A

Haemophilus (1743 genes)

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11
Q

No cell wall, requires nearly all small molecules for survival

A

Mycoplasma (470 genes)

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12
Q

Accessory genetic elements are common in

A

Bacteria

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13
Q

What are 5 accessory genetic elements that are common in bacteria?

A

Plasmids, viruses (i.e. bacteriophages), Insertion sequences, Transposons, and pathogenicity islands

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14
Q

Chromosomes, plasmids, and viruses have sites for initiation of

A

DNA synthesis

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15
Q

Molecules with these sites are classified as

A

Replicons

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16
Q

Many replicons also have sites for partition of replicated DNA into

A

Daughter cells

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17
Q

Are not replicons and only replicate when integrated into one

A

Insertion sequences, transposons, and pathogenicity islands

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18
Q

Mostly circular DNA

-there are many types

A

Plasmids

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19
Q

Genetic parasites that inject genomes into the bacterial cell to use its machinery for their replication

A

Bacteriophages

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20
Q

Release progency by lysis of the cell that they took over

A

Virulent (or lytic) bacteriophages

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21
Q

Insert genomes into bacterial chromosome and replicate as part of it

A

Temperate bacteriophages

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22
Q

Viruses that integrate their genome with bacteria are called

A

Proviruses or prophages

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23
Q

Later, the provirus can then excise from the chromosome, replicate, and

A

Lyse the cell

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24
Q

Non-viral genes can become incorporated into a

A

Provirus

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25
Q

Expression of most genes in a provirus is blocked by a

A

Provirus-endocded repressor

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26
Q

Virulence genes, especially toxins, are often found in

A

Proviruses

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27
Q

Can move from one location to another in DNA

A

Insertion sequences

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28
Q

Insertion sequences contain only the machinery for their own movement. This is the gene for

A

Transposase

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29
Q

An enzyme that catalyzes movement

A

Transposase

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30
Q

Insertion sequences can move because inverted repeats at the termini of the transposase gene are recognized by

A

Transposase

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31
Q

A sequence of nucleotides that is the reverse complement of another sequence located farther downstream

A

Inverted repeat

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32
Q

Resemble insertion sequences, but contain genes unrelated to transposition

A

Transposons

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33
Q

Antibiotic-resistance genes frequently form part of

A

Transposons

34
Q

There are three steps in the evolution of a

A

Transposon

35
Q

First, an insertion sequence inserts near an

A

Antibiotic-resistance gene

36
Q

Second, a copy of the insertion sequence then inserts on the other side of the

A

Antibiotic-resistance gene

37
Q

Can now act to move both insertion sequences and the DNA between them

A

Transposase

38
Q

Damage or loss of the internal inverted repeats however, has what effect?

A

Locks structure together

39
Q

Appear to be very large transposons, contianing up to 50-100 genes

A

Pathogenicity islands

40
Q

May contain a ‘complete kit’ of virulence genes

A

Pathogenicity islands

41
Q

A non-pathogen + a pathogenicity island =

A

Pathogen

42
Q

Most pathogenic strains contain multiple

A

Pathogenicity islands

43
Q

Virulence genes & genes for antibiotic resistance are often found in

A

Plasmids and viruses

44
Q

Plasmids and viruses have mechanisms for transfer of DNA between

A

Bacterial cells

45
Q

Do NOT get moved by plasmids/viruses

A

Chromosomes

46
Q

Can move chromosomal genes to plasmids/viruses, enabling rapid spread within and between bacterial populations

A

Transposons

47
Q

DNA transfer between bacterial cells takes place by which three mechanisms?

A

Transformation, conjugation, transduction

48
Q

DNA is released by the lysis of one cell and then taken up by another

A

Transformation

49
Q

DNA transfer by direct cell-to-cell contact

-Requires participation of a conjugative plasmid

A

Conjugation

50
Q

Bacterial DNA packaged into a virus particle

-Transferred to another cell on infection

A

Transduction

51
Q

A common feature of bacterial DNA transfer is that the transfer is

A

Unidirectional

52
Q

Contains a complete copy of its own chromosome plus the chromosome fragment from donor cell

A

The recipient cell

53
Q

The donated fragment is unstable, and it is lost unless it combines with the

A

Recipient chromosome

54
Q

Required in order for the donated fragment to be incorporated into the recipient genome

A

DNA homology

55
Q

Occurs naturally in a few species of bacteria

A

Transformation

56
Q

Conjugation requires a

A

Plasmid

57
Q

Encodes all biochemical functions required for DNA transfer

A

Plasmid

58
Q

In conjugation, usually the DNA transferred is only

A

Plasmid DNA

59
Q

Highly efficient form of DNA transfer

A

Conjugation

60
Q

The best studied conjugated plasmid is the

A

F-plasmid (or F-factor) of E. Coli

61
Q

In the transfer of the F-1 plasmid, the transfer is one-way, The transfer occurs from

A

Plasmid-contianing F+ cells to plasmid-free F- cell

62
Q

F-like plasmids with multiple antibiotic-resistance genes

A

R-factors

63
Q

Transfer of bacterial genes by viruses

-Occurs via 2 modes

A

Transduction

64
Q

A virus particle may contain bacterial and not viral DNA in

A

Transduction 1

65
Q

A virus genome may incorporate one or more bacterial genes in

A

Transduction 2

66
Q

All viral progeny contain the bacterial chromosomal gene and this gene will be present in new proviruses formed by these progeny in

A

Transduction 2

67
Q

All have special mechanisms for their insertion into chromosomal DNA

-Can bypass the requirement for DNA homology

A

Proviruses, insertion sequences, and transposons

68
Q

Continual production of new antigenic variants

A

Antigenic phase variation

69
Q

Pathogen turns specificity of immune response against itself, and new variants escape response to initial antigens in

A

Antigenic phase variation

70
Q

Antigenic phase cariation has prevented the development of vaccines against

A

Malaria, Trypanosomiasis,and Gonorrhea

71
Q

Created by programmed alterations in DNA

A

Antigenic phase variation

72
Q

Unlike random mutations, these changes are designed to happen

A

Antigenic phase variations

73
Q

Can be exactly reversed by the same process that created it

A

Antigenic phase variation

74
Q

Inversion of segment DNA, recombination between expressed and silent genes, and stuttering by polymerase during copying of a repeat are the three mechanisms of

A

Phase variation

75
Q

The salmonella genome contains two genes for

A

Flagellin

76
Q

However, only one form of the flagellin is expressed at a given time. The two forms of flagellin are termed

A

H1 and H2

77
Q

Created by a DNA inversion, catalyzed by a specific enzyme

A

Flagellar phase variation

78
Q

This enzyme is called

-for H inversion

A

hin

79
Q

Recognizes two inverted repeats and inverts the DNA between the repeats

A

hin

80
Q

Inversion separates H2 gene from its promoter and allows the expression of

A

H1

81
Q

In Neisseria, phase variation in pili is produced by recombination between

A

Expressed and silent pilin genes

82
Q

In Neisseria, the reading frame is maintained and the outer membrane protein PII is produced if the CTCTT repeat is present in multiples of

A

Three

Microbiology Lecture Slides (24 decks)

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