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

2. 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.

3. Beyond Dominant and Recessive Alleles
Wednesday; April 4, 2012

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

5. 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)

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

7. 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

8. 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.

9. 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

10. Work Session
Complete the Beyond Dominant and Recessive Alleles Worksheet.