3-Bacteria Genetics

Question 1

genetic material

Answer 1

1. large circular DNA chromosme, single, all genes for survival
2. small circular plasmid, can be sep or integrated into chromo, rep/transferred to daughter cells

Question 2

why highly regulation gene expression

Answer 2

1. prevent waste of energy
2. prevent targeting by host immune so only produce immunogenic proteins when need
3. quickly respond to changing environ

Question 3

operon

Answer 3

promoter for binding RNA polymerase
-drives expression of multi genes

Question 4

regulon

Answer 4

genes that are regulated as a unit, multi operons being controlled at once
-one sensor/signal activates or represses multiple genes i.e heat shock

Question 5

population level regulation

Answer 5

quorum sensing by chem molecules (autoinducers)
-sense when reach certain pop then can act certain genes to resp

Question 6

vertical gene transfer

Answer 6

genes passed to daughter cells via replicaton
-normal process of binary fission

slower to develop antibiotic resistance than horizontal

Question 7

horizontal gene transfer

Answer 7

1. conjugation
2. transformation
3. transduction

Question 8

homologous recombination

Answer 8

exchange DNA b/t two molecules based on homology aka sequence similarity
-replace chromo sequence with a similar acquired sequence

Question 9

transformation

Answer 9

uptake of free DNA from environ
-to allow bact to gain new traits quickly

Question 10

transformation mechanism

Answer 10

1. DNA actively imported into cell
2. homologous recomb, if doesnt happen then will die

Question 11

conjugation

Answer 11

acquire new DNA directly from another living bacteria

Question 12

F-factor

Answer 12

aka fertility factor for conjugation that carries
1. tra genes- encode sex pilus for DNA transfer
2. oriT - origin of transfer, single strand break

@plasmid or chromo

Question 13

conjugation mechanism

Answer 13

single strand DNA transfer from donor to recipient either
1. chromosome transfer w/ homo recomb
2. plasmid transfer by normal DNA rep

Question 14

conjugation recipients

Answer 14

only F-
no F factor

Question 15

conjugation donors

Answer 15

Hfr (high freq of recomb)
F+

Question 16

F+ x F-

conjugation

Answer 16

sex change of F- to F+

only single strand transferred unidirectionally
-genome not transferred just plasmid F factor

Question 17

Hfr x F-

conjugation

Answer 17

no sex change so stays F-
tra genes not transferred so wont make sex pilli
-does have new bacterial genes

Question 18

transduction

Answer 18

transfer of bact DNA via bacteriophage

Question 19

phage life cycles

Answer 19

1. lytic/virulent phage- replication upon entry
2. temperate phage- lysogeny, will integrate into chromo, excise at some point and enter lytic

Question 20

generalized transduction

Answer 20

accidental
-lytic phage incorps bact chromo into phage head (instead of phage genome)

when phage infects another bacteria DNA incopr into chromo via homo recomb (bc no lytic or lysogenic behavior)

Question 21

specialized transduction

Answer 21

1. lysogenic infects bacterium and integrates as prophage
2. insert near gal gene
3. adverse event causes excision to lytic cycle
4. small part of bact chromo packaged with the phage

Question 22

categories of antibiotic resistance

Answer 22

1. intrinsic- no target
2. chromo mediated
3. plasmid mediated

Question 23

intrinsic antibiotic characteristics

Answer 23

1. not transferable horizontally
2. no inc among populations
3. lack target of the drug

Question 24

chromosomal mediated characteristics

Answer 24

1. random mutations during rep
2. acquisition of resistant DNA thru horizontal transfer + incorp into genome via homo recomb

Question 25

plasmid-mediated characteristics

Answer 25

plasmids carry genes that encode proteins
1. R-factors (resistance)

Question 26

R factor components

Answer 26

1. resistance transfer factor- equiv to F- factor, has all proteins needed for conj
2. resistance determinant- gene for drug resistance

Question 27

transposons

Answer 27

-mobile DNA elements that can transfer themselves into new molecule

Question 28

transposons contain

Answer 28

1. indirect repeat seq on each end for recognition (palindromic)
2. single gene TnpA for transposase movement/jumping
3. single or multi antib resistance genes

Question 29

integrons

Answer 29

-site specific recomb (instead of homo)
-capture antibiotic gene cassettes so important for spread of multi drug resistance

integrase enzyme

Question 30

pathogenicity islands

Answer 30

aka large transpons with virulence genes surrounded by insertion sequences
-region is acquired by horizontal
-do not encode resistance