8.8 Nonmendelian Genetics: Incomplete, Codominance, and Multiple Alleles

incomplete dominance

heterozygous phenotype is intermediate (BLENDING)

ex. RR = red, R’R’ = white

heterozygous: RR’ = pink

codominance

both alleles are phenotypically expressed at the SAME TIME

ex. some cows

BB = brown, WW = white

heterozygous: BW = brown + white

multiple alleles

>2 alleles code for trait b/c mutations

ex. blood type!

3 possible alleles: I^A, I^B, i

A and B are codominant, O recessive

blood

living tissue made up of: rbc, wbc, platelets, plasma (45% of blood volume)

plasma: water and molecules (remaining 55%)

accounts for 7-10% of body weight

avg male: 12 pints

avg female: 9 pints

body immediately makes more blood, so can donate up to 6X/ year

blood phenotypes and genotypes

A → I^AI^A, I^Ai

B → I^BI^B, I^Bi

O → ii

AB → I^AI^B

type o blood

universal donor

type ab blood

universal acceptor

antigen

molecules on rbc surface

can carry certain protein

antibody

proteins by wbcs that trigger immune response

Rh factor gene

protein on rbs (or not), diff gene than ABO

positive or negative blood

Rh negative

does not have protein

recessive

genotype: - - or rr

universal donor

Rh positive

does have protein

most people

dominant

genotype: ++ or + - or RR or Rr

universal acceptor

blood group / can give to: / can get from:

A → A, AB → O, A

B → B, AB → O, B

O → O, A, B, AB → O

AB → AB → O, A, B, AB

Rh F + → + → +, -

Rh F - → +, - → -