10 (a) One gene can have several different alleles - Edexcel - GCSE Biology - Question 10 - 2021 - Paper 1

Alleles are variations of a gene that arise due to differences in their DNA sequences. Each allele can have different base pairs due to mutations, which might lead to a distinct mRNA strand. As a result, the mRNA may code for different amino acids, resulting in a different sequence of amino acids in the protein. This variation in the order of amino acids causes the protein to fold into unique three-dimensional structures, affecting its function. Thus, different alleles can lead to the production of proteins with distinct structures.