Contents
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.
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| 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.