The ancestral state of the TAS2R38 gene is C145, C785,
G886—so the nontasting alleles arose after the human lineage split from other primates. Research suggests that the ability to detect the bitter tastes in food may have had a selective
advantage in avoiding poisonous plants, many of which are bitter.
The purpose of this experiment is to test which of us (out of six selected people) have carried on that selective trait.
So far I have isolated six DNA samples using a saline (0.9% saline solution (NaCl)), microcentrifuge and a thermal cycler, and I have amplified the DNA by PCR. The next steps will be to digest samples with HaeIII, and analyze gel by electrophoresis.
The PCR machine is currently heats PCR tubes at 91˚ to amplify the DNA. Soon the DNA double helix separates, creating two single-stranded DNA molecules. After it cools down to about 50˚C, single-stranded DNA molecules naturally attempt to pair up. The extra primer sequences lock onto their target before strands can rejoin. Then it will heat back up to 72˚C which activates DNA polymerase. When DNA polymerase locates a primer attached to a single DNA strand, it begins to add complementary nucleotides onto the strand. After three times through this process the final product are two strands that begin with primer one and end with primer two. These specific DNA strands are copies of just the segment of DNA you have targeted.