A-LEVEL BIOLOGY AQA NOTES
using genome projects
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- DNA sequencing is the process used to determine the precise sequence of nucleotides in a length of DNA
- The technique whole-genome shotgun sequencing is used. The genome is cut into smaller fragments and individually sequenced. The entire genome is then reassembled by computer algorithms, which align sections of DNA that overlap.
- Next-generation sequencing methods have recently been developed which are faster, more automated and cheaper.
- Whole-genome sequencing allows the genomes of many individuals within a species, to be compared.
- This can have important medical implications by looking for associations between substitution mutations (single nucleotide polymorphisms, SNPs) and susceptibility to disease.
- In simpler organisms, such as pathogens, genome sequencing allows the proteome to be determined. This can help determine potential cell surface proteins that act as antigens, which can be used in vaccine development.
- In more complex organisms, determining the proteome is more difficult due to the presence of introns, regulatory genes affecting the expression of other genes & the effect of epigenetic changes.