DNA sequencing determines the exact order of nucleotides within a DNA molecule.

Sanger sequencing is a method involving radioactive labelling of bases and gel electrophoresis.

1. DNA is mixed with a primer, DNA polymerase, nucleotides (A, T, G, and C), and terminator bases
2. Double-stranded DNA is split into single strands and primers anneal to the DNA
3. DNA polymerase adds nucleotides to the single-stranded template to build new DNA strands
4. When a terminator base is randomly added instead of a normal base, DNA synthesis stops
5. This produces all the possible fragment lengths of DNA
6. DNA fragments are separated according to length (e.g. by gel electrophoresis)
7. Fluorescent markers identify the final base of each fragment and lasers detect the sequence order
8. The sequence order on the new, complementary DNA strand is used to determine the order on the original DNA strand

Terminator bases are modified nucleotides that stop DNA synthesis when they are included.

Capillary sequencing or gel electrophoresis can be used used to separate DNA fragments by length.

Computers are able to reassemble genomes by comparing and overlapping DNA fragments.

Next-generation sequencing involves all automated, high-throughput DNA sequencing technologies.

This automation can help to speed up sequencing projects and reduce costs.

Fluorescent tags are important in DNA sequencing as they identify the final base on each fragment.

DNA sequencing, especially next-generation sequencing, allows for precise identification of genetic disorders and cancers.