Science Genes Help!?

Question

This is the question-
Do all genes have one dominant trait and one recessive trait? the answer is no! one trait does not dominate over another...this can occur in two ways, INCOMPLETE DOMINANCE AND CO-DOMINANE. describe using two examples these two phenomena and be sure to explain the difference between the two and be sure to explain the difference between the two. WHAT DOES THAT MEAN?? please help!!

thanks

Answer 1

Co dominance is when two alleles are equally dominant - a good example are blood groups. i.e. A and B are both dominant over O but not over each other. Therefore if you get both A and B your blood group is AB. (AO or AA = group A, BO or BB=group B, OO= group O)

Incomplete dominance is when a certain allele will show up if present but it's effect is "diluted" by the recessive allele.

The classic example of this is the colours of carnations.

R is the allele for red pigment. R' is the allele for no pigment.

Thus, RR offspring make a lot of red pigment and appear red. R'R' offspring make no red pigment and appear white. RR' and R'R offspring make a little bit of red pigment and therefore appear pink.