11 1.3 Methodologies used in genetics Polypeptides Transcripts Melanin Normal allele A Genotype / A Genotype / a Genotype / Tyrosinase enzyme Phenotype of melanocyte Tyr Pigmented Normal allele Normal allele Nucleus of melanocyte Pigmented Mutant allele Mutant allele Mutant allele Albino Melanin No melanin Mutant active site (inactive) change in shape or size can result in an absence of bio-logical function (which would be the basis of a null al-lele) or reduced function. More rarely, mutation can lead to new function of the protein product. only hereditary mechanisms, but all biological mecha-nisms. Many different methodologies are used to study genes and gene activities, and these methodologies can be summarized brieFy as follows: 1. Isolation of mutations affecting the biological process under study. Each mutant gene reveals a genetic component of the process, and together the mutant genes show the range of proteins that interact in that process. 2.
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