BIO 2133 Chapter 4: Extension to Mendelian Genetics
1 Mar 2018
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Gene interaction: single phenotype is affected by more than one set of genes. Loss of function mutation: mutation causes protein to lose its function; change conformation of its enzyme and reduce or eliminate its affinity for the substrate, or complete loss of function (null allele) Gain of function mutation: mutation that enhance the function of the wild-type product; increase quantity of gene product (i. e affect regulation of transcription of gene) Neutral mutation: mutation is detected when gene is examined, but there is no detectable change in function, no apparent phenotypic change. Incomplete dominance: cross btwn parents with contrasting traits (dominant alleles) may produce offspring with a blended intermediate phenotype with a heterozygous genotype i. e pink flower created from homozygous red flower and homozygous white flower. F1 generation cross from two different homozygous = 100% intermediate phenotype. F2 generation cross from two heterozygotes = 1:2:1 ratio. Threshold effect: normal phenotypic expression occurs anytime a certain level of gene product is attained.
