352SLecture06_S11 - Genetics and Evolution: Lecture #6 1....

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Genetics and Evolution: Lecture #6 Modifcations to Mendelian Patterns Today’s Topics 1. Dominance 2. Penetrance and expressivity 3. Multiple alleles 4. Gene interactions Readings: Pierce, pgs. 99 – 117; 119 - 120 Dominance Dominance : heterozygote has the same phenotype as one of the homozygotes. Incomplete dominance : heterozygote phenotype is intermediate between the 2 homozygote phenotypes. Example: Fower color ( Figure 5.2 )
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Dominance Codominance : heterozygote expresses phenotypes of both homozygotes. Example : MN blood types - L M codes for M antigen - L N codes for N antigen - L M L M expresses antigen M – blood type M - L N L N expresses antigen N – blood type N - L M L N express BOTH antigen M and N – blood type MN Summary – Table 5.1 . Penetrance and Expressivity Penetrance : percentage of individuals having a particular genotype that expresses the expected phenotype. Expressivity: the degree to which a character is expressed. Example: Polydactyly in humans. - Controlled by a dominant allele - Not all who have allele have extra Fngers or toes. - Sometimes extra Fngers and toes are fully functional - Other times extra Fngers and toes are small tags of skin. Figure 5.3
Background image of page 2
3 Multiple Alleles Multiple Alleles: Genes with more than 2 alleles Example : feather pattern in mallard ducks. -
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 9

352SLecture06_S11 - Genetics and Evolution: Lecture #6 1....

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online