Polygenic Inheritance Flashcards
Give an example of a gene that is codominant at the molecular level
Sickle Cell gene
ABO blood types
What is complete dominance?
The trait is dictated by the dominant allele in both the homozygote and the heterozygote
What is codominance?
The phenotype of the heterozygote is a mixture of both homozygous phenotypes
Describe and give an example of a lethal gene?
Overo allele in horses
Homozygous foals die within a few days (ww)
Also known as LWFS- lethal white foal syndrome
What is polygenic inheritance?
Control of a trait by 2 or more genes and the environment
What is the distribution of polygenic inheritance in the population?
Bell shaped distribution
Give examples of traits controlled by polygenic inheritance?
Skin colour Eye colour Hair colour Body shape Height Weight
What is epistasis?
A form of interaction between non-allelic genes that control at trait
When does epistasis occur?
When a gene at one locus influences the expression of a gene at another locus
Where is epistasis common?
Fur colour
Petal colour
Does epistasis control dominant or recessive genes?
Both
What is hybrid vigour (heterosis)?
Where offspring perform better than both pure-bred parents
What does hybrid vigour influence?
Multiple genes producing quantitative variation
What is pleiotropy?
Multiple effects of a single gene on independent traits
Give an example of pleiotropy traits
Mohan’s white coat and crossed eyes
Sickle cell anaemia caused by abnormal haemoglobin Hb gene
