Denaturing the DNA
PCR Time Warp
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In a dramatic manner, go and find some goggles and put them on. The goggles will act as a prop and prompt for the time warp in the demonstration. Place the fake DNA sample and other chemicals in the Eppendorf tube, place the Eppendorf tube in the Styrofoam float, and place it in a warm water bath that is heated to 94oC for 10 minutes (to activate enzymes) and 90 seconds (the denaturing). When finished, dramatically take your goggles off.
Discussion
During this fake 90 seconds,
prompt your students to hypothesize and deduce what will happen in the
Eppendorf and to the DNA pictured on the board (be funny about the fact that
this discussion is taking place in another time frame such that you will come
back to the wet demo in 90 seconds). You could have students with different
hypotheses come to the board and relate their ideas. In the end, lead them to
the fact that the high temperature causes the DNA in the Eppendorf to
‘Denature’. The hydrogen bonds between the DNA nucleotides become broken
creating two single strands of DNA.
Chalkboard
Redraw the DNA strands on the board showing that they are now separated.
5’ ATCGCTTACGTCAACT 3’ original strand
3’ TAGCGAATGCAGTTGA 5' original strand
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