AQA A Level Biology

Revision Notes

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

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While studying Biochemistry at Oxford University, Amelia started her own tutoring service, helping to connect Science tutors with students in her local area. Amelia has experience teaching the sciences and Maths at all levels to UK and international students and, as well as being our Biology Lead, designs revision resources for Chemistry.
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