A
Vector = the term used for an agent that can carry something
from one organism to another.
One
type of Vector often used to transfer genes is a Plasmid.
Plasmids
are small circular pieces of DNA found in most bacteria. They
are completely separate from the main bacterial DNA and lie
freely in the cytoplasm. They are not however useless and
many contain genes which make bacteria resistant to a particular
antibiotic.
Scientists
often use this antibiotic resistance to ensure that their
required gene has been inserted into a plasmid to make the
new recombinant DNA molecule. Using them as Genetic markers.
This
is carried out as follows: -
The
recombinant plasmid will no longer be able to express Ampicillin
resistance .
However,
not all the plasmids will take up the Donor DNA and some will
just re-glue themselves back together.
How
do we identify which plasmids contain the gene we require
and which have not?
