WWLPT

"Fishing for Microsatellites"|

PCR Demo

Put on your goggles and transfer the DNA sample back to the 94^oC water bath and leave it for 90 seconds (faking the time is OK).  Transfer it to the 54^oC water bath for 90 seconds, and finally transfer it to the 72^oC water bath for 90 seconds.

Discussion

First quiz your students on the three processes in a single PCR cycle: ‘Denature, Anneal, Extend.  Challenge them to hypotheses what the sample in the Eppendorf should look like by the end of these three processes.  The important thing that they should end up realizing is that after the DNA denatures, the primers will bond and extend DNA nucleotides on both the original strands and the primer strands.

Chalkboard

By this time your board is getting a bit cluttered and it should look something like what is pictured below.  You may actually wish to have the primer only strands in a separate column from the primer and original strands.  This way you will be able to focus on the number of primer only strands after this next cycle.

5’ ATCGCTTACGTCAACT 3’        original strand
3’ TAGCGAATGCAGTT     5’         primer strand

5’      CGCTTACGTCAA      3’        primer strand
3’ TAGCGAATGCAGTT     5’         primer strand

5’      CGCTTACGTCAACT 3’        primer strand
3’      GCGAATGCAGTT     5’         primer strand

3’ TAGCGAATGCAGTTGA 5’        original strand
5’      CGCTTACGTCAACT 3’        primer strand

| Next Demo | Back Demo | Back to PCR Time Warp |