Hey guys,
ive got a non-3/4 bio question. (its unit 2 bio)
What is the point of reversibly dissociating a double helical structure into two single DNA chains?
(So heating it to dissociate and then cooling so the chains re-associate)
Thanks
this involves some knowledge of unit 4 bio (correct me if I'm wrong), but heating a DNA double helix to split them into respective single strands can have some uses, mainly 2 (you'll be taught this in unit 4).
1) Polymerase chain reaction (PCR), which is a technique used to replicate DNA (and lots of it) by heating DNA double strands to form single strands then attaching nucleotides on the 2 single strands to form a copy of double stranded DNA (this process is then repeated to form more and more copies of DNA).
2) DNA-DNA hybridisation, which is used to determine the relatedness between two species. For example, if you want to test the relatedness between a banana and a human being you can extract both their DNA, heat them up to split their DNA into single strands and mix their DNA together. By cooling it down some DNA strands would combine with DNA strands of the other species, forming hybrid DNA strands. (also because nucleotides only form bonds with complementary nucleotides eg. A to T, C to G, there will be some unconnected parts of the hybrid DNA strands as some nucleotides from the DNA single strand of 1 species are not complementary to the DNA single strand of the other species). This, would make the hybrid DNA strand easier to be split into single strands again just by heating it up (they generally split at a lower temperature), so the lower the temperature in which the DNA strands are split, the less related the two species. (I hope I explained this well)