BI111 Lecture Notes - Lecture 1: Mendelian Inheritance, Panmixia, Genotype Frequency
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Genetics Lecture Notes
Mutation Rates
Vary within and between taxa
Higher in RNA viruses than in DNA viruses
Higher in mitochondrial DNA than in genomic DNA
Genetic code has both specificity and redundancy
Genetic code established very early in evolution of life and has remained virtually
unchanged
Types of Mutation
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Many alleles, varying effects on phenotype
Example: Cats
Have 2 alleles:
L (dominant, short hair)
l (recessive, long hair) (lower case l)
**in order for a cat to be long hair, it must have 2 copies of the recessive gene homozygous)**
**a cat can have short whether it has two copies of the dominant gene (homozygous) or one
copy of the dominant and one copy of the recessive gene and still come out as short hair**
Epistatic: where an allele of one gene hides or masks the visible output, or phenotype, of another
gene (pattern)
Pleiotropic: a single gene that controls more than one trait
Ex. The “dense pigment” gene, “D” codes for melanophilin, a protein involved in the
transportation and deposition of pigment into a growing hair.
2 alleles: (explains white cats vs colored cats)
D (dominant) – functional melanophilin
d (recessive) – less functional melanophilin (dilutes hair color)
Piebald Spotting gene “S” is responsible for whether coat has white patches (incomplete
dominance)
2 alleles:
s (recessive) – homozygotes have no white hair
S (incomplete or partial dominance) – some white hair
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