6.1 Interactions between the Alleles of a single gene: Variations on Dominance
multiple alleles/allelic series: the known mutant alleles of a gene and its wild-type
Complete Dominance and recessiveness
Full/complete dominance : allele that expresses itself the same in single copy
(heterozygote) as in double copy (homozygote).
Null mutation: a mutation that results in complete absence of function for the gene.
Dominant Negative mutation: mutant allele that in a single dose (heterozygote) wipes
out gene function by a spoiler effect on the protein.
For most genes, a single copy is adequate for full expression (haplosufficient), and null
mutations are fully recessive. Harmful mutations of haplosufficient genes are often
dominant. Mutations in genes that encode units in homo- or heterodimers ca behave as
dominant negatives, acting through “spoiler” proteins.
Incomplete Dominance: heterozygot