Question on Plasmid Cloning

Student mucineer at
Tue Aug 10 05:27:43 EST 1999

Dear All

As a new comer to molecular biology, I have the following trivial question
and hope someone can help:

When ligating a DNA insert into a plasmid (both the insert and plasmid
contain different restriction sites on either ends, e.g. a BamHI----HindIII
fragment into a vector digested with these two restriction enzymes), is
there anything in the process that prevent different molecule of the insert
from "self-ligating" to form species such as
HindIII-------BamHI--------HindIII or BamHI--------HindIII------BamHI?

This should be a common problem to all ligations but it doesn't seem to be a
big problem as I usually get hundreds of colonies on the plate.
Does anyone have any insights into this?

Any comments will be appreciated.

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