AQA A Level Biology复习笔记8.3.1 Genome Sequencing Projects

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 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 their DNA sequence that are atypical of the species


Human Genome Project

  • In the 1980s Cambridge scientists had been working on sequencing the genome of a nematode. As they progressed they realised that the technology used in this research could be applied to the human genome
  • 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
  • DNA samples were taken from multiple people around the world, sequenced and used to create a reference genome
  • Laboratories around the globe were responsible for sequencing different sections of specific chromosomes
  • It was decided that the data created from the project 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


  • 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


Applications of Human Genome Project

  • The information generated from the HGP has been used to tackle human health issues with the end goal of finding cures for diseases
  • Scientists have noticed a correlation between changes in specific genes and the likelihood of developing certain inherited diseases
    • The mechanism which causes these inherited diseases to develop is not yet understood. It is being actively researched by thousands of scientists


  • For example, several genes within the human genome have been linked to increased risk of certain cancers
    • If an individuals BRCA1 and BRCA2 genes are mutated then they are substantially more likely to develop breast cancer


  • There have also been specific genes linked to the development of Alzheimer's disease