Microbial Genetics

Question 1

Bacterial chromosome

Answer 1

single, large circular DNA molecule

contains all genes for survival

Question 2

Plasmid

Answer 2

small, circular DNA molecule

replicated and transferred to daughter cells

Question 3

Homologous recombination

Answer 3

exchange of DNA between two DNA molecules based on sequence similarity

Question 4

What happens after homologous recombination takes place?

Answer 4

DNA incorporated into the chromosome are passed to daughter cells/become a permanent part of the genome

Question 5

Transformation definition

Answer 5

uptake of free DNA from environment

Question 6

purpose of transformation

Answer 6

allow bacteria to gain new traits quickly

Question 7

Process of transformation

Answer 7

DNA is released into environment, gets actively imported into the bacterial cell. Homologous recominbation can occur.

Question 8

What type of DNA does transformation use

Answer 8

any

Question 9

Conjugation definition

Answer 9

DNA transfer directly from one bacteria to another via cell contact

Question 10

purpose of conjugation

Answer 10

acquire new DNA

Question 11

Process of conjugation

Answer 11

• mediated by fertility factor (F-factor)
• also has oriT
• single stranded DNA transferred from donor to recipient cell

Question 12

tra operon

Answer 12

in the F-factor, encodes components of the sex pillus

Question 13

oriT

Answer 13

origin of transfer. Where a single strand break occurs for transfer. in the F-factor

Question 14

What happens in an F+ F- mating

Answer 14

transfer is unidirectional
F- becomes F+
only a single strand is transferred
no bacterial genes are transferred
does not require homologous recombination

Question 15

What happens in an Hfr F- mating

Answer 15

F- stays F-

requires homologous recombination

Question 16

Transduction definition

Answer 16

transfer of bacterial DNA via bacteriophage

Question 17

Generalized transduction

Answer 17

i. a lytic phage incorporates bacterial chromosomal DNA into its phage head
ii. when the phage infects another bacteria the DNA can be incorporated into its chromosome via homologous recombination

Question 18

What type of DNA is used in generalized transduction

Answer 18

any

Question 19

Specialized transduction

Answer 19

i. a lysogenic phage incorporates into the chromosome as a prophage
ii. an event (e.g. UV damage) leads to conversion to a lytic lifecycle
iii. upon excision from the genome, a small portion of the chromosome directly adjacent to where the phage was integrated is packaged into a phage head

Question 20

Is homologous recombination used in transduction?

Answer 20

yes

Question 21

Does transduction use free DNA?

Answer 21

no

Question 22

Does transduction require cell to cell contact?

Answer 22

no

Question 23

Intrinsic Antibiotic resistance

Answer 23

not transferable between bacteria

not increasing among bacterial populations

Question 24

Chromosomal-mediated antibiotic resistance

Answer 24

arises through random mutations during replication

acquisition of DNA through horizontal gene transfer and incorporation into the genome via homologous recombination

Question 25

Plasmid-Mediate antibiotic resistance

Answer 25

genes encoding antibiotic resistance located on a plasmid
These plasmids carry genes that encode proteins that degrade of modify an antibiotic or an efflux pump to pump the antibiotic out of cell
Has resistance factor

Question 26

Resistance factor

Answer 26

conjugative plasmid

equivalent to F-factor (encodes all proteins needed for conjugation)

Question 27

Transposons

Answer 27

mobile DNA elements that can transfer themselves (or a copy) from one molecule of DNA to another
present in both eukaryotic and bacterial cells, as well as viruses

Question 28

What do transposons contain

Answer 28

indirect repeat sequences on each end
a single gene for transposase
contains a single or multiple antibiotic resistance genes

Question 29

transposaae (TnpA)

Answer 29

enzyme required for transposon movement

Question 30

Integrins

Answer 30

diverse group of genetic element
encode a site specific recombination system
can capture antibiotic resistance cassette
coordinately express them under control of integron promoter

Question 31

resistance gene cassettes

Answer 31

carry genes that confer antibiotic resistance.