Biochemistry 2280A Chapter Notes - Chapter 10: Transcriptional Regulation, Dna Microarray, Sanger Sequencing
1 Jan 2017
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Humans have been experimenting with dna without realizing it for millennia: dogs, plants = selective breeding. Unlike a protein, a gene does not exist as a discrete entity in cells: small part of a larger dna molecule. Certain bacteria always degraded (cid:498)foreign(cid:499) dna that was introduced in them experimentally. Bacteria own dna is protected from cleavage by chemical modification of these specific sequences nuclease cleaves dna at specific nucleotide sequences. Enzymes function to restrict the transfer of dna between strains of bacteria. Different bacterial species produce different restriction nucleases, each cutting at a different specific nucleotide sequence: targets are short so many sites of cleavage will occur (purely by chance) in any dna molecule. Each enzyme will cut a particular dna molecule at the same size. For a given sample of dna, a particular restriction nuclease will reliability generate the same set of dna fragments. The size of the resulting fragments depends on the target sequences of the restriction nucleases.
