AQA A Level Biology复习笔记8.3.1 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