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Do all genetic traits follow the rules of dominance & recessiveness?

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Presentation on theme: "Do all genetic traits follow the rules of dominance & recessiveness?"— Presentation transcript:

1 Do all genetic traits follow the rules of dominance & recessiveness?

2 Codominance Prefix ‘co’ means to exist together The dominant and recessive alleles appear together in the phenotype of the offspring – red x white = red and white spotted (roan)

3 Cross a roan cow with white cow Genotypes RW: 50% WW: 50% Phenotypes Roan: 50% White: 50%

4 Solving some difficult genetic predictions. Incomplete Dominance of Traits – A mixed expression of the trait conditions resulting from the inability of either allele to mask the other completely.

5 Cross two heterozygous pink snapdragon flowers Rr X Rr Genotypes RR 25% Rr 50% rr 25% Phenotypes Red 25% Pink 50% White 25%

6 Sex-Linked Traits -Genetic traits that are carried on the “X” chromosome only. -“Y” chromosome does not carry a matching allele, this explains the higher rate of occurrence in males of certain traits.

7 A female that is not color blind but is a carrier marries a man who is not colorblind? What are the chances of having a color blind baby? Genotypes X B X B 25% (50%) X B X b 25% (50%) X B Y 25% (50%) X b Y 25% (50%) Phenoytpes Normal female 50% (100%) Normal male 25% (50%) Colorblind male 25% (50%)


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