Use of databases to identify the locus of a human gene and its polypeptide product

• Following the?sequencing of the whole human genome, we now know the?exact locus?(position) of every gene across the 23 pairs of chromosomes
• Online databases have been built that are able to?locate any known gene or allele
• Anyone can access these loci
  • One example is the?European Molecular Biology Laboratory?database (EMBL)

  Examples of genes that can be located are

  • The?CFTR protein, critical to?cystic fibrosis, on chromosome 7
  • HBB, a faulty allele of which is the cause of?sickle-cell anaemia, on chromosome 11

  If we know the locus of a particular gene, medicine can establish the location of a faulty allele, which is often recessive

  • A faulty allele can be cut out of the chromosome by genetic engineering using?recombinant DNA technology
  • Replacing a faulty allele could lead to?genetic therapy
  • Location databases of?cancer-related genes?are often vital information to researchers, doctors and patients involved in cancer genetics

  Use of Databases: Comparing Base Sequences

Use of a database to determine differences in the base sequence of a gene in two species

• The Genbank? database is another that can be used to?search for DNA base sequences
  • Uses a computer data analysis technique called BLAST (Basic Local Alignment Search Tool) to spot and 'line up' similar base sequences

  A protein common to all organisms is cytochrome C

• This makes its gene sequence a good one?to compare between organisms
• The sequence is available for many different organisms?across all three?domains
• This gives important information about?evolutionary relationships between organisms

The use of databases to compare base sequences (and protein sequences) between species