Conjugation

Question 1

what is the transconjugant

Answer 1

recipient cell that has received a plasmid

Question 2

What are self-transmissable plasmids

Answer 2

plasmids that are able to transfer to a new bacterium

Question 3

What are mobilizable plasmids

Answer 3

Plasmids that encode some of the functions required for transfer but use the machinery of certain self0transmissble plasmids to transfer

Question 4

What is the general model of conjugation in gram negative bacteria

Answer 4

Fertility plasmid

Question 5

What are the 2 distinct origins of replication of F plasmid

Answer 5

oriV for normal vegetative replication (bidirectional) and oriT for replication accompanied by transfer to another cell (conjugation

Question 6

Conjugation overview

Answer 6

Formation of mating pair signals to relaxase
relaxase and helicase make single-strand nick at oriT, relaxase and helicase translocated to recipient cell with DNA, DNA is pumped out of donor cell and relaxase seals nick in recipient, replication complete and separation of pair occurs

Question 7

Functions of Mpf

Answer 7

The pilus
The channel
The coupling protein

Question 8

What is the pilus

Answer 8

Allows cell to make contact with other bacterial cells
grappling hook

Question 9

what is the channel

Answer 9

the channel through which DNA is transferred

Question 10

What is the coupling protein

Answer 10

Contact is communicated via the coupling protein to initiate DNA cleavage and transfer
also pumps DNA into recipient

Question 11

What is the Dtr and what are the 3 components

Answer 11

DNA Transfer and Replication
1) relaxase: endonuclease, DNA strand is transported with relaxase to the recipient cell, relaxase recircularizes the transferred DNA to make a ssDNA circle
2)Relaxosome- act with relaxase at ariT, function unclear
3) primase- expands host-range of self-transmissable plasmids

Question 12

What is the oriT

Answer 12

Site where plasmid transfer is initiated by nicking relaxase. Helicase loads and unwinds the DNA and the site where transferred DNA is recircularized

Question 13

action of relaxase

Answer 13

use a DNA cleavage and rejoining mechanism similar to topoisomerase and telomere resolvases
also recircularizes the transferred DNA

Question 14

What are promiscuous plasmids

Answer 14

Plasmids that have transfer systems that can transfer to many different species

Question 15

What is special about the Ti plasmid of agrobacterium tumefaciens

Answer 15

encodes two distinct conjugal transfer system, one for bacteria the other to plants
Only T-DNA is transferred to plants