Genome Sequencing Projects (AQA A Level Biology): Revision Note

Genome sequencing projects

• A genome contains all of the genes within an organism

• Advances in technology have allowed scientists to map and sequence the genes within an organism's genome

• Genome sequencing can aid in the understanding of gene function and interaction

• Sequencing projects have read the genomes of a wide range of organisms, from flatworms to humans

• A genome project works by collecting DNA samples from many individuals of a species. These DNA samples are then sequenced and compared to create a reference genome

  • More than one individual is used to create the reference genome, as one organism may have anomalies/mutations in its DNA sequence that are atypical of the species

The Human Genome Project

• The Human Genome Project (HGP) began in 1990 as an international, collaborative research programme

• It was publicly funded so that there would be no commercial interests or influence, the results were also would be made publicly available

  • As a result, the data can be shared rapidly between researchers

  • The information discovered could also be used by any researcher and so maximised for human benefit

• DNA samples were taken from multiple people around the world, sequenced and used to create a reference genome

• By 2003 the human genome had been sequenced to 99.9% accuracy

• The finished genome was over 3 billion base pairs long but contained only about 25,000 genes

  • This was much less than expected

• Following the success of sequencing the human genome scientists have now moved onto sequencing the human proteome

  • The proteome is all of the proteins that can be produced by a cell

  • Although there are roughly 25,000 genes within the genome there are many more proteins within the proteome. This may is due to processes such as alternative splicing and post-translational modification

• There is also work being done on the human epigenome

  • These are the inherited changes in DNA that do not involve a change in DNA base sequence