Heterozygous grey is the dominant allele incomplete

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Unformatted text preview: minant allele incomplete dominance - heterozygous with white and black, that mixed Grey AwAb is heterozygous incomplete dominance phenotype, black is homozygous AbAb or Grey Gg is heterozygous dominant phenotype, black is homozygous recessive gg how to prove: breed them.. somehow, and look for the white cow 8 What is the mode of inheritance of coat colour ? heterozygous, grey is the dominant allele, both are homozygous dominant, or recessive. incomplete dominance - heterozygous with white and black, that mixed, and mixed again. 9 What is the mode of inheritance of coat colour ? Incomplete dominance. new phenotype - white cow. shows the incomplete dominance. 10 What is the mode of inheritance of coat colour ? 1:2:1 = codominance or incomplete dominance? - white and black mixed hairs. distance appears grey. therefore. codominance 11 Multiple alleles of a single gene e.g., ABO blood groups 12 Codominance: • The gene controlling the cell surface sugars responsible for the ‘ABO’ blood grouping system is a multiple allele system in which IA and IB are co- dominant to each other but they are both dominant to the i allele. • Allele IA attaches a sugar diferent to that of allele IB and allele i does not attach the sugar at all. • Heterozygotes IAIB have both types of sugars on their cell surface. Phenotype (blood type) Possible genotype AO, AA A BO, BB AB B O AB 13 O Codominance is described by phenotype Blood type A sugar (A antigen) AB - codominant A and B sugars B sugar (B antigen) Lipid stalk Blood type B A = X A (i is recessive) A O No sugar X = 14 •  •  •  •  IA = makes enzyme A to add A sugar IB = makes enzyme B to add B sugar i = no enzymes - no sugars added IAIB = both enzymes to add both A + B sugars •  single gene (I) with altered alleles (IA + IB + i ) IA + IB are codominant to each other and dominant to i Polymorphic gene as the 3 alleles are commonly found 15 Variations on complete dominance are consistent with Mendel’s law of segregation The type of dominance relationship exhibited by dif...
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This document was uploaded on 02/25/2014.

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