PCR primers

Dr. Duncan Clark drc at nospam.demon.co.uk
Tue Jul 25 07:07:08 EST 2000


In article <%v4f5.1081$WM6.81753626 at news1.mtl.metronet.ca>, Tina
<anfortin at webnet.qc.ca> writes
>It is possible to find the location of upper and  lower primers in the gene
>sequence in order to know if or not they will generate a PCR product
>included in one exon or covering two exons.
>For the upper primer, we have just to find it directly in the gene sequence,
>but for the lower primer it is necessary to "translate" the primer sequence
>in complementary bases and after to invert it before searching it in the
>gene sequence. Why the upper ca be find directly and not the lower ?
>I can't stay more time without undertanding this basic point of PCR
>technique .

Think DNA not gene sequence. DNA is double stranded and the product you
amplify will also be double stranded, therefore you need primers
complementary to both strands i.e. an upper and lower primer, one for
each strand.

 Primer 1
 -------->
5------------------------------------------------3
3------------------------------------------------5
                                        <--------
                                         Primer 2

Duncan
-- 
The problem with being on the cutting edge is that you occasionally get 
sliced from time to time....

Duncan Clark
DNAmp Ltd.
Tel: +44(0)1252376288
FAX: +44(0)8701640382
http://www.dnamp.com
http://www.genesys.demon.co.uk






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