Q. 25 B5.0( 2 Votes )
For sequencing the total DNA from the cell, two methods are used. These are ESTs (Expressed sequence Tags) and sequence annotation.
In ESTs method the part of DNA is transcribed into mRNA and translated into proteins. Later, it focuses on sequencing the part denoting a gene.
In sequence annotation: For sequencing in this method, the total DNA from a cell is isolated and converted into random fragments of relatively smaller sizes and cloned in suitable host using specialised vectors. The cloning results in amplification of each piece of DNA fragment.
The fragments are sequenced using automated DNA sequencers, which worked on the principle of a method developed by Fredrick Sanger for determination of amino acid sequences in proteins. These sequences were then arranged based on some overlapping regions present in them.
Specialized computer-based programmers are developed, and these sequences are subsequently annotated and assigned to each chromosome.
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