Conjugation

Question 1

summarize conjugation

Answer 1

direct contact of 2 cells with a pilus forming a mating pair to transfer one strand of DNA using rolling circule replication

Question 2

what is Lederberg and Tatum’s experiment

Answer 2

mixed different auxotrophic strains and got strains unlike parents strains
- suggests that strains are a result of cell fusion, transforming factors, bacteria sex

Question 3

what is the fertility plasmid

Answer 3

gene responsible for transformation
100 kb long

Question 4

what is Mpf mating pair formation

Answer 4

responsible for the formation of the pilus for contact
- makes pore for DNA transfer as well

Question 5

what is plasmid SOS response

Answer 5

stops remodeling of DNA as its being transferred into another cell

Question 6

what is Dtr DNA transfer and replication component

Answer 6

prepares DNA for replication when transferring into other cell

Question 7

what is surface exclusion

Answer 7

prevents multiple transfers of plasmid

Question 8

what are tra genes

Answer 8

transfer genes required for transfer from donor to recipient

Question 9

what are pilin proteins

Answer 9

proteins that make up the pilus from the tra regions of f+ plasmids.
- attaches to receptor of recipient for contact

Question 10

what is type IV secretion system

Answer 10

system involved in pilus formation but more specifically a multi-protein machine involved in delivery of DNA

Question 11

what are 2 usages of type IV secretions system

Answer 11

-delivery of DNA (donor/recipient)
-delivery of virulence factors

Question 12

what is the role of relaxosomes

Answer 12

bind at Ori T of F plasmid to prepare for transfer
- rolling circle replication of DNA into recipient

Question 13

what is relaxase Tra I

Answer 13

protein part of relazosome
- endonuclease that nicks 5’ at ori T to form transester bond
- directs DNA into recipient during pore formation
- re-circularizes transfer strand via transester bond in recipient

Question 14

what is the role of TraY and host IHF

Answer 14

essential accessory proteins for nicking at 5’

Question 15

what is TraM and TraD

Answer 15

coordinate DNA (Mpf genes for processing)

Question 16

what is TraU

Answer 16

Dtr component that prepares plasmid for transfer

Question 17

what are coupling proteins

Answer 17

coupling of DTR and MPF components–> TraD
- turns type IV secretion system to secretion of DNA

Question 18

what does it mean when TraD provides specificity

Answer 18

specifies what proteins are required to transfer DNA (since they vary between Gm-/ Gm+)

Question 19

what is TraD translocator

Answer 19

similar to FtsK in which it directs replicated DNA into recipient cell

Question 20

what is the role of TraJ

Answer 20

protein responsible for transcription of Tra Genes
(remember tra genes are required for transformation)

Question 21

what is the role of FinP

Answer 21

inhibits TraJ mRNA translation–> step to inhibit Tra genes for transformation

Question 22

what is the role of FinO

Answer 22

works with finP to block reading of TraJ

Question 23

what are the mechanisms that regulate DNA transfer

Answer 23

-TraJ leads mRNA transcript of pilin proteins for pilus

-after entry into cell and some hours pass, finO concentration increases which creates finO protein

• finO protein binds to finP, finP transcribes opposingly to traJ to make double stranded dna which degrades
• degradation prevents mRNA from translation

Question 24

what are self transmissible plasmids

Answer 24

plasmids that encode all genes required for transfer

Question 25

what are mobilizable plasmids

Answer 25

plasmids in the same host cell as a self-transmissible plasmid can use proteins synthesized by self-transmissible plasmids for transfer

Question 26

what does it mean when mobilizable plasmids are promiscuous

Answer 26

they can transfer dna between any species even though unrelated increases evolution and genetic diversity antibiotic resistance factors

Question 27

what are Hfr strains

Answer 27

high frequency recombination transferred plasmid is integrated in host chromosome with tra genes which lead to high homologous recombination rates

Question 28

what are F' factors

Answer 28

imprecise excision in which plasmid is excised with some of chromosomal DNA

Question 29

what is triparental mating steps

Answer 29

1. strain carrying self permissible plasmid 2. strain containing mobilizable plasmid 3. empty recipient strain self transmissible strain helps mobilizable strain move into recipient useful in labs

Question 30

what are toxin-antitoxin systems

Answer 30

pair of toxin and antitoxin which prevents toxin from killing cell after segregation, antitoxin cell may degrade causing toxin expression leading to cell death

Question 30

what are toxin-antitoxin systems

Answer 30

pair of toxin and antitoxin which prevents toxin from killing cell after segregation, antitoxin cell may degrade causing toxin expression leading to cell death