An allele is one of a number of alternative forms of a gene.Alleles may arise by mutation. The different alleles have different base sequences and therefore code for different polypeptides.Each individual inherits a gene from each parent. They may inherit the same alleles from each parent or the alleles may be different.The polypeptides will have a different sequence of amino-acid and may function differently.Sometimes mutation gives rise to alleles with loss of function. If the protein coded for is an enzyme, the shape may change and this may reduce the function of the protein.
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Specification: AQA Biology (7401), AS-level, 3.4.1 DNA, genes and chromosomes. Topic: DNA, Genes and Protein Synthesis.
Key terms in this lesson
- gene
- A length of DNA that codes for a polypeptide or a functional RNA molecule, at a specific locus on a chromosome.
- mutation
- A random change in the amount, arrangement or base sequence of the DNA of an organism.
More in DNA, Genes and Protein Synthesis
- The Genetic Code
- Features of the Genetic Code
- Chromosomes
- Homologous Chromosomes
- The Human Karyotype
- Protein Synthesis
- RNA
- mRNA
All 15 lessons in DNA, Genes and Protein Synthesis · All AQA AS-level Biology topics