Gene

Key Stage 3

Meaning

A gene is a small unit of DNA that provides instructions for a specific feature of an organism.

About Genes

There is a gene that controls eye colour with a different version of the gene for each colour.

There is a gene that controls whether a person has a widow's peak or not.

There are a number of genes that control the colour of a person's skin or the shape of their nose.


An eye colour gene controls the colour of a person's eyes.	There are several genes that determine the number of spots on a dalmatian.	The shape of bird's beak is caused by a number of genes working together.	A "widow's peak" is controlled by a particular gene.

Key Stage 4

Meaning

A gene is a small unit of DNA that provides instructions for a specific feature of an organism.

About Genes

There can be several alleles of the same gene. A human will inherit one allele of a gene from their mother and another allele of a gene from their father.

Only some characteristics are coded for by one gene. Most characteristics are controlled by a large number of genes in the genome.

Genes can be divided into two categories:

Coding DNA - Genes which are 'expressed' which means used as the templates for protein synthesis.
Non-coding DNA - Genes which affect whether other genes will be expressed. These genes are said to 'turn off' parts of the DNA and can respond to environmental changes.