Figure 1.4: Schematic representation of a locus and alleles
The position of a gene on a particular chromosome is known as its locus. In chromosome pairs, a particular gene is present on both chromosomes at the same locus. Where alternative forms of a gene exist, they are termed alleles. For example in this case, gene A can exist as 'A' or the variant 'a'. Where both alleles in a chromosome pair are the same (ie, AA or aa), the individual is termed homozygous.
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