The genome is all of the genetic material in an organism. In humans it is the complete DNA base sequence in one set of chromosomes, including the small circular DNA found in mitochondria.The human genome contains about 3.2 billion base pairs, organised into 23 pairs of chromosomes in most body cells. Only about 20,000 of these sequences are genes that code for proteins, and less than 2% of the genome codes for protein. The rest is non-coding DNA, which includes regulatory sequences that control when genes are switched on, sequences that code for functional RNA, and long stretches of repeated sequences.The Human Genome Project set out to determine the base sequence of the entire human genome. It was an international project and it was completed in 2003. The genomes of many other organisms, from bacteria to crop plants, have now been sequenced.Knowing the genome of an organism allows scientists to:
• find the location and sequence of genes, and predict the amino acid sequence of the proteins they code for
• identify mutations and alleles linked to disease
• compare the genomes of different species to study evolution.The genome is almost identical in every cell of an organism, but different cells use different parts of it. The full set of proteins that a cell or organism can produce is called its proteome. Because one gene can give rise to several different proteins, the proteome is larger than the number of genes suggests.
• find the location and sequence of genes, and predict the amino acid sequence of the proteins they code for
• identify mutations and alleles linked to disease
• compare the genomes of different species to study evolution.The genome is almost identical in every cell of an organism, but different cells use different parts of it. The full set of proteins that a cell or organism can produce is called its proteome. Because one gene can give rise to several different proteins, the proteome is larger than the number of genes suggests.