Bacterial Genetics

Question 1

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

Answer 1

Genetically identical

Question 2

Rare genetic events that have a substantial probability of occurrence

Answer 2

Corollary

Question 3

In Neisseria gonorrhoeae, resistant mutations accumulate with the use of

Answer 3

Penicillin

Question 4

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

Answer 4

0.015 ug/mL

Question 5

Bacteria can also acquire drug resistance from

Answer 5

Another source

Question 6

Encodes an enzyme that hydrolyzes penicillin

Answer 6

Plasmid-based gene

Question 7

Bacterial genomes are typically made up of a single

Answer 7

Circular DNA molecule

Question 8

A few species of bacteria have

Answer 8

Multiple or linear chromosomes

Question 9

Makes all required compounds from glucose, multiplies outside host

Answer 9

E. coli (4700 genes)

Question 10

Obligate parasite, requires many small molecules for survival

Answer 10

Haemophilus (1743 genes)

Question 11

No cell wall, requires nearly all small molecules for survival

Answer 11

Mycoplasma (470 genes)

Question 12

Accessory genetic elements are common in

Answer 12

Bacteria

Question 13

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

Answer 13

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

Question 14

Chromosomes, plasmids, and viruses have sites for initiation of

Answer 14

DNA synthesis

Question 15

Molecules with these sites are classified as

Answer 15

Replicons

Question 16

Many replicons also have sites for partition of replicated DNA into

Answer 16

Daughter cells

Question 17

Are not replicons and only replicate when integrated into one

Answer 17

Insertion sequences, transposons, and pathogenicity islands

Question 18

Mostly circular DNA

-there are many types

Answer 18

Plasmids

Question 19

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

Answer 19

Bacteriophages

Question 20

Release progency by lysis of the cell that they took over

Answer 20

Virulent (or lytic) bacteriophages

Question 21

Insert genomes into bacterial chromosome and replicate as part of it

Answer 21

Temperate bacteriophages

Question 22

Viruses that integrate their genome with bacteria are called

Answer 22

Proviruses or prophages

Question 23

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

Answer 23

Lyse the cell

Question 24

Non-viral genes can become incorporated into a

Answer 24

Provirus

Question 25

Expression of most genes in a provirus is blocked by a

Answer 25

Provirus-endocded repressor

Question 26

Virulence genes, especially toxins, are often found in

Answer 26

Proviruses

Question 27

Can move from one location to another in DNA

Answer 27

Insertion sequences

Question 28

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

Answer 28

Transposase

Question 29

An enzyme that catalyzes movement

Answer 29

Transposase

Question 30

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

Answer 30

Transposase

Question 31

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

Answer 31

Inverted repeat

Question 32

Resemble insertion sequences, but contain genes unrelated to transposition

Answer 32

Transposons

Question 33

Antibiotic-resistance genes frequently form part of

Answer 33

Transposons

Question 34

There are three steps in the evolution of a

Answer 34

Transposon

Question 35

First, an insertion sequence inserts near an

Answer 35

Antibiotic-resistance gene

Question 36

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

Answer 36

Antibiotic-resistance gene

Question 37

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

Answer 37

Transposase

Question 38

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

Answer 38

Locks structure together

Question 39

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

Answer 39

Pathogenicity islands

Question 40

May contain a ‘complete kit’ of virulence genes

Answer 40

Pathogenicity islands

Question 41

A non-pathogen + a pathogenicity island =

Answer 41

Pathogen

Question 42

Most pathogenic strains contain multiple

Answer 42

Pathogenicity islands

Question 43

Virulence genes & genes for antibiotic resistance are often found in

Answer 43

Plasmids and viruses

Question 44

Plasmids and viruses have mechanisms for transfer of DNA between

Answer 44

Bacterial cells

Question 45

Do NOT get moved by plasmids/viruses

Answer 45

Chromosomes

Question 46

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

Answer 46

Transposons

Question 47

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

Answer 47

Transformation, conjugation, transduction

Question 48

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

Answer 48

Transformation

Question 49

DNA transfer by direct cell-to-cell contact -Requires participation of a conjugative plasmid

Answer 49

Conjugation

Question 50

Bacterial DNA packaged into a virus particle -Transferred to another cell on infection

Answer 50

Transduction

Question 51

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

Answer 51

Unidirectional

Question 52

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

Answer 52

The recipient cell

Question 53

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

Answer 53

Recipient chromosome

Question 54

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

Answer 54

DNA homology

Question 55

Occurs naturally in a few species of bacteria

Answer 55

Transformation

Question 56

Conjugation requires a

Answer 56

Plasmid

Question 57

Encodes all biochemical functions required for DNA transfer

Answer 57

Plasmid

Question 58

In conjugation, usually the DNA transferred is only

Answer 58

Plasmid DNA

Question 59

Highly efficient form of DNA transfer

Answer 59

Conjugation

Question 60

The best studied conjugated plasmid is the

Answer 60

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

Question 61

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

Answer 61

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

Question 62

F-like plasmids with multiple antibiotic-resistance genes

Answer 62

R-factors

Question 63

Transfer of bacterial genes by viruses -Occurs via 2 modes

Answer 63

Transduction

Question 64

A virus particle may contain bacterial and not viral DNA in

Answer 64

Transduction 1

Question 65

A virus genome may incorporate one or more bacterial genes in

Answer 65

Transduction 2

Question 66

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

Answer 66

Transduction 2

Question 67

All have special mechanisms for their insertion into chromosomal DNA -Can bypass the requirement for DNA homology

Answer 67

Proviruses, insertion sequences, and transposons

Question 68

Continual production of new antigenic variants

Answer 68

Antigenic phase variation

Question 69

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

Answer 69

Antigenic phase variation

Question 70

Antigenic phase cariation has prevented the development of vaccines against

Answer 70

Malaria, Trypanosomiasis,and Gonorrhea

Question 71

Created by programmed alterations in DNA

Answer 71

Antigenic phase variation

Question 72

Unlike random mutations, these changes are designed to happen

Answer 72

Antigenic phase variations

Question 73

Can be exactly reversed by the same process that created it

Answer 73

Antigenic phase variation

Question 74

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

Answer 74

Phase variation

Question 75

The salmonella genome contains two genes for

Answer 75

Flagellin

Question 76

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

Answer 76

H1 and H2

Question 77

Created by a DNA inversion, catalyzed by a specific enzyme

Answer 77

Flagellar phase variation

Question 78

This enzyme is called -for H inversion

Answer 78

hin

Question 79

Recognizes two inverted repeats and inverts the DNA between the repeats

Answer 79

hin

Question 80

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

Answer 80

H1

Question 81

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

Answer 81

Expressed and silent pilin genes

Question 82

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

Answer 82

Three