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AQA A2 Biology restriction mapping

Could someone explain restriction mapping to me I feel I kind of understand the process just not how it allows you to put the gene back in the right sequence.
Also I am a bit confused on locating genes as one book I have just says make a radioactive probe complementary to the gene you are looking for then mix the dna and probe and it will bind then put photographic paper over it and it will be exposed were the gene is. But another book starts going on about gel electrophoresis.

Thanks
Reply 1
Avatar for ssamarai
ssamarai
2
https://www.youtube.com/watch?v=yR_heZ4n4Gc for the restriction mapping take a look at this video, i found it quite useful.

with regards to the DNA sequencing, i believe the method where gel electrophoresis is used is called the 'Sanger sequencing method' whereby the single strand of DNA is used as the template to which nucleotides and DNA polymerase are mixed with it. However some of the nucleotides will be 'terminator' nucleotides so stop the synthesis of the second strand prematurely. Basically this means that the DNA is essentially cut at this point. For example if the first 5 bases in the gene are ATCGT and the terminator nucleotide A joins (due to complimentary base pairing) those 5 bases are essentially a separate strand. Basically then you use gel electrophoresis in order to separate out those 'strands' and since it separates them via length you are able to read the sequence backwards in order to get the full DNA sequence.

Sorry this was quite hard to explain but otherwise look up the sanger sequencing method and it should make sense :smile:

Message me for any questions.
Reply 2
Avatar for Ben_2911
Ben_2911
OP
3
Original post by ssamarai
https://www.youtube.com/watch?v=yR_heZ4n4Gc for the restriction mapping take a look at this video, i found it quite useful.

with regards to the DNA sequencing, i believe the method where gel electrophoresis is used is called the 'Sanger sequencing method' whereby the single strand of DNA is used as the template to which nucleotides and DNA polymerase are mixed with it. However some of the nucleotides will be 'terminator' nucleotides so stop the synthesis of the second strand prematurely. Basically this means that the DNA is essentially cut at this point. For example if the first 5 bases in the gene are ATCGT and the terminator nucleotide A joins (due to complimentary base pairing) those 5 bases are essentially a separate strand. Basically then you use gel electrophoresis in order to separate out those 'strands' and since it separates them via length you are able to read the sequence backwards in order to get the full DNA sequence.

Sorry this was quite hard to explain but otherwise look up the sanger sequencing method and it should make sense :smile:

Message me for any questions.


Thanks helped a lot.


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