3C- Genes and Environment
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Polygenic (3)
• characteristic is coded by more than one gene on different loci. • can be influenced by environment • always causes continuouse variation
genotype
allele combination of an organism
phenotype
visible/observible characteristics that are caused by genotype, but also influenced by environment
influence of environment example- siamese cats (3)
• dark fur on these animals is result of melanin produced through enzyme tyrosinase • as a result of mutation, tyrosinase is not working at normal body temp, so melanin is not being produced • in black parts, temp is lower so enzyme is not denatured, melanin is produced
Why can an individual have a greater adult height than their biological parents? (3)
• height is affected by environment, for example: more calcium in diet, better healthcare • height is an example of polygenic inheritance • therefore offspring can inherit a mixture of alleles from both parents
Explain how the height of an adult human demonstrates how environmental factors interact with genotype. (3)
• lack of nutrients such as protein or calcium • nutrients required for muscle, bone growth • disease or health affect the expression of the phenotype for height
examples of polygenic inheritance
eye colour, weight, intelligence, height
discontinuous variation (3)
• shown by features that are either present or not (blood groups, sex) • determined by one gene • environment plays no role
continuous variation (4)
• determined by multiple genes • they are polygenic • affected strongly by environment • examples: weight, height