The Genome (AQA A Level Biology)

The Genome

• A gene is a length of DNA that codes for a polypeptide/protein

• A genome is the complete set of genes present in a cell

• The full genome is present within every cell of an organism, but not every gene is expressed in every cell. Which genes are expressed depends on the cell type

• The proteome is the full range of proteins that a cell is able to produce

• The proteome is usually larger than the genome of an organism

  • This due to the large amount of post-translational modification of proteins (often in the Golgi apparatus)

  • Each gene is also capable of producing multiple different proteins via alternative splicing

Image showing the increasing complexity of the proteome from the genome. Processes such as alternative splicing and protein modification enable the large number of proteins to be produced.