Warm Up What did you learn from your research about sickle cell anemia? We will have a share out about what you learned.

Announcements Sickle Cell Anemia Assignment and Signed Progress Report are due today, 4/2. I will be after school today, 4/2, until 3:00/3:15pm. Today we will complete the Wisconsin Fast Grow Plant Lab. The lab report is Due on Wednesday, 4/4. Sickle Cell Anemia & Mutations Common Task will be given in class on Thursday, 4/5.

Beyond Dominant and Recessive Alleles Wednesday; April 4, 2012

Exceptions to Mendel’s Principles Some alleles are neither dominant nor recessive, and many traits are controlled by multiple alleles or multiple genes.

Incomplete Dominance Incomplete Dominance – Cases when one allele is not completely dominant over another. The heterozygous phenotype is between the two homozygous phenotypes Ex: RR (Red flower) x rr (White lower) = Rr (Pink flower)

Codominance Codominance – Both alleles contribute to the phenotype of the organism

Multiple Alleles Multiple Alleles – when genes have more than two alleles in the population An individual can only have two alleles but a population can have more than two alleles

Sex-Linked Genes Sex-linked Genes – genes located on the X and Y chromosomes Ex: Colorblindness – an inability to distinguish colors More common in males because males have just one X chromosome. In males, all sex-linked alleles are expressed, even if they are recessive.

Sex-Linked Genes A female would need for the allele to be located on both X chromosomes for colorblindness to occur In female cells, one X chromosome is turned off. Ex: Calico Cat are always female because the gene for fur color is located on the X chromosome. Different X chromosomes are expressed on a single cat

Work Session Complete the Beyond Dominant and Recessive Alleles Worksheet.