Revision guides: DNA and the genome

DNA is the molecule that holds the instructions for all living things. DNA achieves this feat of storing, coding and transferring biological information though its unique structure.

DNA replication is the process by which a cell makes an identical copy of its DNA.

Only a fraction of the genes possessed by any particular cell will be expressed. Gene expression is the process by which specific genes are activated to produce a required protein.

When cells express specific genes that characterise a certain type of cell we say that a cell has become differentiated.

DNA replication is carefully controlled to preserve the genetic information. However, changes in the genome do sometimes occur. These changes are known as mutations.

Evolution is the process by which living things change over time, over many generations. These changes are as a result of changes to the genome (genomic variations).

Genomic sequencing is the process by which the sequence of nucleotide bases is determined for individual genes or even entire genomes.