Gene and Environment Interactions Flashcards
Temperature
Siamese cat: fur colour - melanin gene mutation, cool parts of body enzyme produces melanin, warmer parts it’s deactivated
White-blood in Drosophila: flies grown at high temp (30) = light colour eyes, flies grown low temp (15) = dark colour eyes
Light
Arctic hare: lives in north, dark fur summer, light fur winter, light exposure turns off melanin
Plants sensitive to day length, cryptochrome molecules determine day length
Chemicals
Nutritional conditional mutations in bacteria
E.coli can grow on medium lacking certain amino acids as it can synthesise them
(Chemicals) Phenylketonuria (pku)
Amino acid sensitivity in humans, normally can’t break down phenylalanine → tyrosine, leads to build up which can be lethal
(Chemicals) Porphyria
Can’t break down haemin, light sensitive → urine is red
Pharmacogenetics - genetic effects on drug metabolism, Barbiturate doses safe for most → death in porphyria
(Chemicals) Dietary sensitivities
Sugar + type II diabetes, heart disease - fats
Obese mutation in mice - lack leptin hormone, don’t know when to stop eating
Age
Many genes show phenotype after certain age
Huntington’s disease dominant in over 50’s
Expressivity
The extent to which a gene shows itself, often great variation in extent of manifestation
Incomplete penetrance
Carrier doesn’t manifest gene’s effects at all
Sex-limitation
Effects of ‘hormonal’ environment
Dorset Horn Sheep - males have horns, females don’t
In humans: male pattern baldness, autosomal dominant obvious effects only in males but female carriers at higher risk of polycystic ovary
Genotype’s ‘norm of reaction’
Set of phenotypes it will generate given particular set of environments
Genotype’s ‘norm of reaction’
Set of phenotypes it will generate given particular set of environments
