3.8.3 Using genome projects

The Human Genome Project (HGP) was an international scientific research project with the goal of determining the sequence of nucleotide base pairs that make up human DNA, and of identifying and mapping all of the genes of the human genome.Projects to determine the entire DNA nucleotide base sequence of organisms work by mapping the DNA base sequences that make up the genes of the organism and then map these genes on the individual chromosome of that organism. In this way a complete map of all the genetic material in an organism (the genome) is obtained.

The HGP would have been impossible without the use of bioinformatics (the science of collecting and analysing complex biological data, e.g genetic codes). It uses computers to read, store, and organise biological data at a very fast rate and utilises algorithms to analyse and interpret biological data.

Determining the complete DNA base sequence of an organism uses the technique of whole-genome shotgun (WGS) sequencing. This involves researchers cutting the DNA into many small easily sequenced sections and then using computer algorithms to align overlapping segments to assemble the entire genome. Sequencing methods are continuously updated. This and increased automation of the processes involved have lead to extremely rapid sequencing of whole genomes.

One outcome of the HGP is that lots of medical advances have been made. E.g over 1.4 million SNPs (single nucleotide polymorphisms) have been found in the human genome. SNPs are single-base variations in the genome that are associated with disease/disorders. Medical screening of individuals has allowed quick identification of potential medical problems (this is good for early intervention).

The proteins a genome codes for are known as the proteome (all the proteins produced by the genome). A protein is only produced when a gene is switched on. The cellular proteome is all the proteins produced in a given type of cell at a given time under specific conditions. The complete proteome is all the proteins produced in a given organism at a given time under specific conditions.

Determining the genome and proteome of simpler organisms
We sequence the genomes of prokaryotic/single-celled eukaryotic cells to gain information to help cure disease and provide knowledge of genes that can be usefully exploited. E.g ones from organisms that can withstand extreme/toxic environmental conditions and so have potential uses in cleaning up pollutants or in manufacturing biofuels. Determining the proteome of prokaryotes is relatively easy because:

• the vast majority of prokaryotes have just one circular piece of DNA that is not histone associated
• there are none of the non-coding portions (introns) of DNA which are typical of eukaryotic cells

Knowledge of the proteome of prokaryotes has a number of applications. One is the identification of the proteins that act as antigens on the surfaces of human pathogens. These antigens can be used in vaccines against diseases caused by these pathogens. The antigens can be manufactured and then administered to people in appropriate doses. In response, memory cells are formed etc.

Determining the genome and proteome of complex organisms

The problem in complex organisms is translating knowledge of the genome into the proteome. This is because the genome of complex organisms contains many introns (non-coding genes) as well as others that have a role in regulating other genes.