DNA Sequencing (College Board AP® Biology)

DNA Sequencing

• DNA sequencing allows for the nucleotide base sequence of an organism's genetic material to be identified and recorded

• Most methods for sequencing DNA involve the use of chain-terminating dideoxynucleotides

  • The dideoxy chain-termination method was developed by Frederick Sanger in 1977

• The chain-termination method uses modified nucleotides called dideoxynucleotides

  • Dideoxynucleotides have a slightly different structure to standard nucleotides

  • They lack the 3’-hydroxyl group so cannot form a covalent bond with the next nucleotide to be incorporated by DNA polymerase

  • Dideoxynucleotides prevent elongation of the nucleotide chain, which therefore terminates

• Advances in technology have enabled the development of rapid high-throughput sequencing methods which allow scientists to sequence the genomes of organisms rapidly

• Most sequencing methods used are now automated rather than requiring manual interpretation

• The data obtained from sequencing can be entered into computers with specialized programmes that compare the base sequences of different organisms