What is a read?

[Stock]

Hi,
i am a student. I am doind a research about next generation sequencing, and i am not sure to have understood what mean read, and why for each platform there are different read length? for example with solexa the read are long 100 bp while with ABSolid 35.
Can you explein better?
Thank you

[shurjo]

Hi Stock,

A read is a string of the letters A,T,G and C (symbols for the four nucleotides that make up DNA) which is generated by a DNA sequencer and corresponds to the sequence in which those nucleotides are present in the DNA molecule that has been sequenced.

Different platforms have different read lengths because the chemistry and engineering are different for each of these. While an ABI3730 sequencer produces 192 800-bp reads in about 48 hrs, a Helicos Heliscope might produce a few million 25-35 base reads in a same time.

In case you were wondering, the term "read" is used because the sequencer "reads" the DNA, one base at a time, as a human would read a book one page at a time.

Hope this helps,

Shurjo

[adugduzhou]

very good

Hi Stock,

A read is a string of the letters A,T,G and C (symbols for the four nucleotides that make up DNA) which is generated by a DNA sequencer and corresponds to the sequence in which those nucleotides are present in the DNA molecule that has been sequenced.

Different platforms have different read lengths because the chemistry and engineering are different for each of these. While an ABI3730 sequencer produces 192 800-bp reads in about 48 hrs, a Helicos Heliscope might produce a few million 25-35 base reads in a same time.

In case you were wondering, the term "read" is used because the sequencer "reads" the DNA, one base at a time, as a human would read a book one page at a time.

Hope this helps,

Shurjo