Polygenic inheritance Flashcards
define polygenic inheritance
more than one allele/gene for a single characteristic where each gene is at a different locus. they interact with each other and have additive effects to produce a phenotype
what is continuous variation, what is it controlled by and what are some examples
characteristics are affected by both genotype and the environment so there is a range (frequency is a bell shaped curve)
these characteristics are controlled by multiple genes at many loci (polygenetic inheritance)
examples:
height and weight
what is discontinuous variation, what is it controlled by and what are some examples
phenotypes fall into discrete groups with no overlap
characteristics controlled at one single loci (not affected by the environment)
examples:
blood group
eye colour
sex
how are some phenotypes are affected by polygenetic inheritance and how
this can give rise to phenotypes that show continuous variation
in polygenetic inheritance each gene has a small effect on the phenotype
them genes interact and the additive effect of the alleles of many genes produces many different genotypes
more genes involved the greater the number of genotypes
how are phenotypes affected by environment and how it can give rise to phenotypes that show continuous variation
effect of environment can cause more variation resulting in a continuous range of phenotypes
how is phenotype the result of an interaction between genotype and the environment
e.g. for height
genotype gives their potential height
but genotype and environment determines their actual height
