DNA sequencing

What is gene sequencing?

Gene sequencing involves the determining of the order of nucleotides in a DNA sequence.

A DNA template is sequenced using A, C and G nucleotides and a T dideoxynucleotide. Using the DNA template below to work out the complementary DNA fragment.

TTGCCCGAGGGG

AACGGGCTCCCC

Explain how a computer reads the DNA sequence from an electrophoresis gel.

Dideonucleotides are labelled with fluorescent dyes. The computer uses a laser to read the fluorescent dyes at the end of each DNA fragment as it passes the end of the electrophoresis gel.

Name two uses of gene sequencing in biology

1. Compare human genome sequences

2. Examine evolutionary relationships.

New gene sequencing techniques are currently used to speed up the process. Describe one technique.

DNA templates are attatched to microbeads and many copies are made using polymerase chain reaction. The templates can be sequenced in parallel.