1. Epigenetics

2. Phenotype: result of gene expression
May be easily observable traits
Shape
Size
Color

3. Phenotype May require a special test to observe Blood type in humans
Hip joint stability in dogs

4. What’s the Phenotype?
More than one trait can be observed!

5. What’s the Phenotype? Color Shape of ears Length of hair
Herding instinct

6. Phenotype results from Genes
Genes are the instructions for phenotype; called genotype
You get genes from your parents
You therefore resemble your parents

7. Phenotype is not all caused by the genes
Epigenetics: environment influences genes
Internal Environment – cell contents and neighbors
External environment – outside the body

8. Internal Factors
Earliest cells are totipotent (able to become anything)
As time passes, they become limited in what they can produce

9. Cloning
Convince a totipotent cell that it is an embryo by transplanting the totipotent cell’s nucleus into an ova without a nucleus
Result: copy of donor
[some differences affecting aging]

10. Cloning

11. Clones also happen naturally…same DNA

12. Clones are NOT identical!
Rainbow & CC

13. As the embryo ages, some genes are turned OFF.
Rainbow could express both orange and grey fur, but CC only expresses grey.
In females, one X chromosome is deactivated early in embryonic development.
Similarly, embryonic cells develop limits for their fate.

14. Different portions of the Embryo have different Fates
Fate Maps – show what portion of a zygote becomes what portion of the embryo (or placenta)

17. Ligers and Tigons Hybrids, so usually sterile
Effect of egg protein is visible
Liger:
male lion and female tiger
Typically much larger than either parent
Tigon:
male tiger and female lion
Often smaller than both parents

18. Liger

20. Pleuripotent: can become many types of cell, but not all

21. Transplants and Grafts

22. Could be useful for humans

23. Other Cells influence gene expression
Affect whether mitosis happens
Affect which genes are expressed

24. Environment influences Phenotype
Accident, disease, and other factors can change phenotype

25. Environment influences Phenotype
Accident, disease, and other factors can change phenotype

27. A Few Classic Examples Bees: Royal Jelly transforms larvae into Queens
Fertile; larger abdomen
Unbarbed stinger

29. Crocodiles
Egg incubation temperature causes gender

30. An example in Humans
Poor diet can lead to people being stunted - smaller than their genes’ instructions