Conjugation Flashcards

1
Q

summarize conjugation

A

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

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2
Q

what is Lederberg and Tatum’s experiment

A

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

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3
Q

what is the fertility plasmid

A

gene responsible for transformation
100 kb long

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4
Q

what is Mpf mating pair formation

A

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

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5
Q

what is plasmid SOS response

A

stops remodeling of DNA as its being transferred into another cell

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6
Q

what is Dtr DNA transfer and replication component

A

prepares DNA for replication when transferring into other cell

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7
Q

what is surface exclusion

A

prevents multiple transfers of plasmid

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8
Q

what are tra genes

A

transfer genes required for transfer from donor to recipient

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9
Q

what are pilin proteins

A

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

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10
Q

what is type IV secretion system

A

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

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11
Q

what are 2 usages of type IV secretions system

A

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

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12
Q

what is the role of relaxosomes

A

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

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13
Q

what is relaxase Tra I

A

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

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14
Q

what is the role of TraY and host IHF

A

essential accessory proteins for nicking at 5’

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15
Q

what is TraM and TraD

A

coordinate DNA (Mpf genes for processing)

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16
Q

what is TraU

A

Dtr component that prepares plasmid for transfer

17
Q

what are coupling proteins

A

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

18
Q

what does it mean when TraD provides specificity

A

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

19
Q

what is TraD translocator

A

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

20
Q

what is the role of TraJ

A

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

21
Q

what is the role of FinP

A

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

22
Q

what is the role of FinO

A

works with finP to block reading of TraJ

23
Q

what are the mechanisms that regulate DNA transfer

A

-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
24
Q

what are self transmissible plasmids

A

plasmids that encode all genes required for transfer

25
Q

what are mobilizable plasmids

A

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

26
Q

what does it mean when mobilizable plasmids are promiscuous

A

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

27
Q

what are Hfr strains

A

high frequency recombination

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

28
Q

what are F’ factors

A

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

29
Q

what is triparental mating steps

A
  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

30
Q

what are toxin-antitoxin systems

A

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

30
Q

what are toxin-antitoxin systems

A

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