Determining Protein Sequences (AQA A Level Biology)

Sequencing DNA to Determine Protein Sequences

• The genome of simpler organisms can be used to obtain the proteome (the sequences of the proteins) of the organism

• This information can be used for a range of applications

  • For example, identifying potential antigens for use in vaccine production

• Large databases are created containing information about an organism's gene sequences and amino acid/protein sequences

• Once a genome is sequenced bioinformatics allows scientists to make comparisons with the genomes of other organisms using the many databases available. This can help to find the degree of similarity between organisms which then gives an indication of how closely related the organisms are and whether there are organisms that could be used in experiments as a model for humans (eg. the fruit fly Drosophila)

• The nematode Caenorhabditis elegans is an animal that has been used as a model organism for studying the genetics of organ development, neurone development and cell death. It was the first multicellular organism to have its genome fully sequenced and as it has few cells (less than 1000) and is transparent. It has been a useful model

The Malaria vaccine

• Plasmodium falciparum is a species of parasite that causes severe forms of malaria

• Thousands of these parasites have been used for genome sequencing

• Scientists have been searching for differences between their DNA sequences to identify the genes that display the highest level of variation between individuals

  • A high level of variation suggests that those genes are under strong selective pressure. These genes could code for the antigen proteins found on the parasites

• Once the antigenic genes are identified the antigen they code for can be used in vaccine production

  • The protein coded for by the specific gene would be injected into people living in areas with malaria to see if they produce antibodies that provide immunity against the disease

• There is also research being done to identify genes within the parasite's genome that affect drug resistance and insecticide resistance

• Genes that help to protect against severe malaria have also been identified within the human genome