Variable expressivity - Variable expressivity Same genotype...

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Variable expressivity Same genotype but expressed a little bit different Ex: Lobe Eye Ex: Bar eye : correlation of temperature and expression Pleiotropy: gene causes a change -Phenylketonuria *The metabolic pathway of phenylalanine Excess Phenylalanine turns into Tyrosine Gene: inability to metabolize phenylalanine which gives a defect in myelin sheet which gives a person mental retardation Excess amounts of Tyrosine it gets converted to Acid and gets eliminated very quickly Albinism: lack of pigmentation: Tyrosinase turns into Melanin Melanin absorbs ultraviolent light Environmental alteration; -In some cases, altering the environment can cause phenotypes to change – Phenocopies *Himalayan coat pattern in mice and rabbits Dark fur conserves the heat of the appendages Black fur associated with skin temperature Altering the environment we can alter the phenotype *Siamese cats Gene-gene interactions
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9:3:3:1- genes that are assorted independently
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Unformatted text preview: Epistasis is the condition in which one gene can control whether another is expressed In general we refer to any condition controlled by two genes as being epistatic Epistasis of seem as modi-Activity of one gene controls the affect of another gene *Coat color in Labrador Retrievers Two genes control coat color E gene controls the presence or absence of pigment in the hairs with absence leading to golden color Coat patter in mice- Normal Agoutic coat pattern results from differential deposition of color in the hairs Five distinct eye colors Brown , blue, green .grey, and hazel Control by 3 genes 2 Alleles G and g GG and Gg are green Gg is blue EyeCL3 Gene B and b BB, Bb – brown bb- blue B_G_Brown bbG_ Gteem bbgg blue Accounts for Brown, Green, and blue but not Hazel and Grey EYCL2 is poorly understood Genes lead to phenotypes Some variability to expressing the genes Genetic Plasticity-...
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  • Spring '14
  • *Himalayan coat pattern, control coat color, Normal Agoutic coat, person mental retardation

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