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Published byLynn Wilkerson Modified over 9 years ago
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Environment and Phenotype Upper Sixth Biology
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Aims To understand The effect of the environment on the phenotype Specific examples The function of the lac operon in E coli
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Phenotype Phenotype = Genotype + environment Height in humans Fur colour in the Himalayan rabbit Many characteristics are determined by the information help in the genes and also the environment
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The lac Operon in E coli E coli is a bacteria normally found in the gut It needs enzymes to carry out the breakdown of nutrients Lactose permease, Β galactosidase The expression of these genes depends on the environment If the bacteria is grown in glucose, it doesn’t produce either If grown in lactose, both genes are expressed
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Some work SAQ 4.22 please, in your books Why waste the resources to make enzymes that you don’t need?
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The lac operon What is an operon? A length of DNA that holds the base pairs of a structural gene (one that makes a protein) and another base sequence which determines whether or not the mRNA to make the structural genes are transcribed or not.
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Lac operon Lactose present
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The lac Operon in E coli- no lactose present
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Lac operon Animation Lac operon
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