Answer:
Sequencing of human genome has made it
possible to understand the link between various genes and their functions. If
there are any gene defects that express as disorders or that increase the
susceptibility of an individual to a disease then specific gene therapies can
be worked out
Methodoiogies of human genome
sequencing
The methods involve two major
approaches
(i) Expressed Sequence Tags (ESTs)
This method focusses on identifying all the genes that are expressed as RNA.
(ii) Sequence annotationIt
is an approach of simply sequencing the whole set of genome that contains all
the coding and non-coding sequences, and later assigning different regions in
the sequence with functions.
For sequencing, first the total
DNA from cell is i.e., solated and broken down in relatively small sizes as
fragments.
There DNA fragments are cloned
in suitable host using suitable vectors. When bacteria isused as vector, they
are called Bacterial Artificial Chromosomes (BAG) and when yeast isused as
vector, they are called Yeast Artificial Chromosomes (YACs).
Frederick Sanger
developed a principleaccording to which the fragments of DNA aresequenced by
automated DNA sequences.
On the basis of overlapping
regions on DNA fragments, these sequences are arranged;accordingly. For
alignment of these sequences, specialized computer-based programmeswere
developed.
Finally, the genetic and
physical maps of the genome were constructed by collectinginformation about
certain repetitive DNA sequences and DNA polymorphism, based onendonuclease
recognition sites.
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