1. Complex Inheritance of Human Traits

2. Codominance With codominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype in which both of the parental traits appear together..

3. Codominance Examples

4. Multiple Alleles Control: 1. blood type: I A, I B, i I A and I B are codominant Table on page 331 It is important that one know his/her blood type Blood transfers Parentage

7. Polygenic Inheritance Inheritance controlled by two or more genes (Aa x Bb x Cc) found on same or different chromosomes Ex. Stem length in plants, skin color

8. Controlled by 3-4 pairs of genes Genes are controlled by the production of melanin (a chemical that adds brown color to the skin; the darker a person is the more melanin one has) Skin Color

9. Non-Disjunction Failure of the chromosomes to separate during meiosis. This may result in offspring either having too many chromosomes or not enough

10. Down’s Syndrome Extra 21 st chromosome Trisomy 21 Karyotype 

12. Monosomy X Female missing a chromosome X Turner’s syndrome

13. Klinefelter’s Syndrome Male with extra chromosome (XXY)

14. Genetic Disorders Causes errors in the genetic material Sickle Cell Anemia – red blood cells have a sickle shape instead of an oval. Found in African Americans Mostly or dark – skinned people. Cells clog blood vessels causing pain and early death

15. Normal Blood CellSickle Cell

16. Environment can play a major role in genetics 1. Internal factors – Hormones Horn Size 2. External factors—Arctic Fox Temperature Nutrition Light Chemicals Infectious agents