6. Inbreeding, dihybrid crossing and types of dominance

why is inbreeding biologically a bad idea

• Most people carry 1 to 2 recessive alleles for serious genetic disorders

• Relatives have an increased chance of carrying the same recessive alleles (this increases the chance of having offspring with a genetic disorder)

what is a dihybrid cross

a dihybrid cross is a cross in which 2 separate pairs of traits are observed - RRGG,rrgg — R = round (dominant), r = wrinkled (recessive) G = grey (dominant) g= clear (recessive)

types of dominance : Complete dominance

when one allele (dominant), if present, will completely mask the effect of the other(recessive)

Ex.) TT,Tt

types of dominance : incomplete dominance

when both alleles blend together to create a third, in between, phenotype

Ex.) HcHc = curly + HsHs= straight ——> HcHs = wavy

types of dominance : Co- dominance

When both alleles are expressed

Ex.) a cows skin is co-dominance because it expresses both a black and white colored skin allele