1. Warm up (in ISN):
One cat carries heterozygous, long-haired traits (Ss), and its mate carries homozygous short-haired traits (ss). Use a Punnett square to determine the probability of one of their offspring having long hair.

2. Practice 2:
In pea plants, spherical seeds (S) are dominant to dented seeds (s). In a genetic cross of two plants that are heterozygous for the seed shape trait, what fraction of the offspring should have spherical seeds?

3. Practice 3
A white flowered plant is crossed with a plant that is heterozygous for the trait. What percentage of the offspring will have purple flowers?

4. Practice:
A purebred red cow (R) is crossed with a purebred white cow (r). Draw a Punnett Square depicting this cross, and write down the genotypic and phenotypic ratios resulting form this cross.

5. This is actually the phenotype for heterozygous roan cows!

6. Alternative Patterns of Inheritance
Not every trait works out perfectly-that is, one trait is dominant, one recessive
Exceptions to Mendel’s principles (one dominant, one recessive)

7. Co-dominance
Pattern of inheritance where both alleles are dominant and therefore both phenotypes are expressed
Usually shown by two capital letters
Example: roan cows, chicken feathers
explain blood type/write on board, have them copy it down in notes

8. Co dominance Practice:
In a certain fish, blue scales and red scales are codominant. When a fish has the genotype BR, it has a patchwork of blue and red scales. What happens if you breed this fish with a fish that only has Blue Scales.

9. Incomplete Dominance
Incomplete dominance-one allele is dominant to another only to a certain extent, so it can’t completely express its phenotype
This results in phenotypes that are intermediate
Example: snap dragons:

10. Incomplete/co Dominance Practice:
Cross one white and one pink snapdragon. Give phenotypic and genotypic ratios. (incomplete dominance)
Cross one white chicken and one chicken who has black/white feathers. Give phenotypic and genotypic ratios (co-dominant)
Cross two red/white cows

11. Multiple alleles When there are more than two forms of one gene
Ex: Blood type, A B and O forms
Note-this is also an example of what type of inheritance?

12. Multiple Alleles practice:
Mom has type O blood. Dad has type AB blood. What percentage of their kids will inherit type B blood?

13. Polygenic traits When a trait is controlled by one than one gene
For example eyecolor-look around
Not just blue, green, brown, varying degrees
Eye color

14. Genes and the environment
Environment can influence expression of genes
Genes contain information, environment can determine how much of that information is expressed
Example: Western white butterflies, Siamese cats

15. Closure:
Go back to warm up problem. Using what you learned about co-dominance, fix your genotypic and phenotypic ratios-hand into me before you leave

16. Alien Genetics
You are to create your own species of Alien. For your alien, you must create 3 traits
One trait must show normal dominant/recessive relationships
One must be co dominant
One must be incompletely dominant
Cross two purebred individuals showing the different forms of these characteristics and the resulting hybrid offspring
Draw a Punnett square for each cross
Draw each organism, showing the traits