Lecture 8 Flashcards
How are Hfr’s formed?
Formed by homologous recombination between identical copies of insertion sequence/trasnposen on F AND chromosome
What are transposens?
Molecular parasites that encode ability to move themselves
-Both F and chromosome have number of these sequences
How many copies of IS2 does E.Coli K12 chromosome have?
12 copies
How many copies of IS3 does E.Coli K12 chromosome have?
6 copies
What do the IS3 and IS2 regions provide?
Regions of homology with the F plasmid
How many base pairs are in an F plasmid?
100,000
What does the direction of F facing in the chromosome depend on?
Orientation of insertion sequence in the chromosome
Where does F excise from the chromosome?
The same insertion sequence that it was integrated into
What is another way that F is excised from the chromosome?
Through a recombination events resulting in part of the chromosome becoming attached to F plasmid and then deleted from the chromosome
What is the F’ Factor =?
F factor that’s picked up a region of chromosomal DNA, essentially ‘in-vivo cloning vector’
How long does the transfer of an entire chromosome take?
About 100 minutes
What is the likelihood of a gene being transferred closer to the origin of transfer vs further away?
Closer = higher likelihood of transfer, more exconjugates seen
Further = later transfer and decreased likelihood of transferring before interruption
