GEN-3000 Chapter 4: Genetics Textbook Notes, Chapter 4
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Alleles alternative forms of the same gene: wild-type the most common allele, not necessarily dominant, mutant contains modified genetic information. Loss of function mutation produces alleles that encodes for proteins with reduced function or no function. A mutation that produces a gene with no function at all is called a null allele. Gain of function mutation produces an allele that is different from any. Normal allele and is not a loss of function allele. Neutral mutation produces no observable phenotypic difference. Ways to distinguish between alleles: capitalize the dominant allele, use a plus symbol to indicate the wild-type allele, use an italic letter with a superscript to differentiate between alleles that are neither dominant nor recessive. Incomplete dominance: also called partial dominance, the heterozygous phenotype is intermediate between those of the homozygous phenotypes, genotypic ratio = 1:2:1, phenotypic ratio = 1:2:1, example : tay-sachs disease.
