codominance

Question 1

what is codominance and what does it lead to?

Answer 1

when a gene has 2 alleles and neither can dominate, both alleles are expressed in the phenotype. this means that a third phenotype arises when there is a heterozygous genotype

Question 2

what is an example of codominance? include drawings of the monohybrid crosses for the parents (red and white) and F1 generations

Answer 2

snapdragons are flowers showing codominance. the allele for white snapdragons is shown as C^W and the allele for red snapdragons is C^R. correct drawing of cross diagram for parents and correct drawing of cross diagram for F1 generation.

Question 3

describe what happens when multiple alleles occur and a description of how this occurs in blood groups.

Answer 3

some genes have more then 2 allelic forms. each individual can have only 2 alleles for each gene but the combinations are more varied so the patterns pf dominance nee to be studied.

the ABO blood grouping system is determined by one gene, with 3 allelic forms. these give rise to 4 blood groups, (phenotypes). alleles I^A and I^B are codominant. allele I^O is recessive to both alleles I^A and I^B.

Question 4

draw a table for the genotypes, antigens and blood group phenotypes

Answer 4

see table