So now, let us examine a
few different host-vector
systems or possibilities. We have seen the
vector as the plasmid in this case and we
have seen the host as a bacteria itself. We
could have E.coli, bacteria as our host organisms. We
could also have yeast cells. Sometimes we
even have viruses as our hosts for which we
put plasmids into. In addition, we might
have mammalian tissue culture or cells in culture
or we could have insect cells. These are some
of the common host models that we have used.
Now we need to talk of vectors. Most commonly
used we will use plasmids. Plasmids could
be taken up bacteria. They could be taken up
viruses and they could be taken up by mammalian
cells or insect cells. Also, it is a little
bit more challenging as we will learn.
The other thing that we have started embarking
upon is artificial chromosomes. Plasmids are
all fine for very small pieces of DNA, but
sometimes we are interested in cloning larger
pieces of DNA. For example, if we were to
sequence the whole genome like the human genome,
then we would need a much larger place or
having a larger storage area for the genetic
information would be highly beneficial.
So we have artificial chromosomes. These artificial
chromosomes have a site for origin of replication,
so on and so forth they have to be functional
chromosomes and we have generated some in
yeast. The first ones were in yeast, YACs and
others are in bacteria, BACs. YACs and BACs. Bacterial
artificial chromosomes, yeast artificial chromosomes
and we have even started to develop artificial
chromosomes for mammalian cells, so linear chromosomes
even and there is a little bit of work going
on in human artificial chromosomes also.
So very exciting room for genetic
technologies or biotechnologies.