1
Q
what is incomplete dominance?
A
neither allele is completely dominant
- alleles inherited from parents
- produces new phenotype
2
Q
what is co-dominance?
A
- neither allele is completely dominant
- alleles are expressed equally
- both phenotypes are seen separately
3
Q
what is sex-linked?
A
genes are carried on sex chromosomes (X & Y)
4
Q
what is sex-influenced?
A
the phenotype depends on the gender of animal
- it is influenced by hormones
5
Q
what are lethal alleles?
A
- pairs of homozygous alleles that can cause an animal to die if they have them
- they can be dominant or recessive
6
Q
what are examples of diseases caused by lethal alleles in humans?
A
- Huntington’s disease
- cystic fibrosis
- sickle cell anaemia
-achondroplasia (dwarfism)
7
Q
what are examples of diseases caused by lethal alleles in animals?
A
- creeper disease in chickens
- roan and Dalmatian colouring in guinea pigs
- yellow fur in mice
- birth amputated in calf legs
8
Q
what are multiple alleles?
A
- multiple alleles may exist where three or more alternative alleles of a single gene are possible
9
Q
what is the epistatic effect?
A
where one gene affects the expression of another gene or phenotype
