Heredity / Genetics

1. Heredity / Genetics Early explanations for heredity? Gregor Mendel published 1865 Consequences of a monk proposing the nature of heredity? Early 1900’s accuracy recognized Grew up on a farm Educated in mathematics (probability) & science Why garden pea plant?

3. Explanation Experimentation led to four basic conclusions: Concept of Unit Characters: Traits are controlled by factors that occur in pairs Law of Segregation: This says that of a pair of characteristics (e.g. blue and brown eye color) only one can be represented in a gamete. Principle of Dominance One factor in a pair may mask the expression of the other Dominant factor vs. Recessive factor Law of Independent Assortment Different pairs of factors are passed to offspring independently of each other.  The result is that new combinations of genes present in neither parent are possible. (flip two pennies & two nickels)

4. Gene for yellow seeds (Y), gene for green (y) P1 = Pure bred cross - YY x yy

5. Essential Terms • Homozygous vs Heterozygous • Dominant vs Recessive • Phenotype vs Genotype • Ratio • Alele • Hybrid • Monohybrid Cross • Dihybrid Cross • P1. F1. F2 • Punnet Square • Pedigree • Gamete • Probability • Product Rule

6. Human examples of Mendelian Traits Listed below are human traits that reveal dominance & recessiveness - All traits listed are the dominant phenotype • Tongue Curling • Widow’s Peak • Free Ear lobe • Brown Pigmented Iris • Hitch Hikers Thumb (45 degree angle) • Shorter Big Toe (shorter in length than second toe) • Mid Digital Hair • Freckles • Rh Factor • PTC taster • Left Thumb Over Top Right - (WhenInterlocking Fingers of both hands) • Short Palmar Muscle (Two tendons back of thumb to wrist is dominant, three is recessive)

7. What about combinations of characteristics? Law of Independent Assortment different pairs of alleles are passed to offspring independently of each other.  The result is that new combinations of genes present in neither parent are possible. If we took two coins what is the probability of flipping one head and one tail? To determine this we must realize that the outcome of one does not influence the outcome of the other. (Independent assortment). Determine all of the possible outcomes Head & Head = (1/2 x 1/2) Head & Tail = 2(1/2 x 1/2) Tail & Tail = (1/2 x 1/2)

8. When Mendel looked at combined characteristics: Flower position (axial & terminal) and stem length (long & short) Pure bred axial flower_round seed producing plant crossed with pure bred terminal flower_wrinkled seed producing plant AARR x aarr = all offspring AaRr F1 all axial flower round seed producing plants (F1 hybrids) F2 parents (AaRr x AaRr) Gametes from AaRr (independent assortment) AR , ar or Ar, aR Axial_round = 9/16 Axial_wrinkled = 3/16 Terminal_round = 9/16 Terminal_wrinkled = 1/16

9. Product Rule: The chance of two random events happening simultaneouslyis equal to the sum of their separate probablilities Two coins both heads = 1/2 x 1/2 = 1/4 Pair of dice both coming up 6 = 1/6 x 1/6 = 1/36 One di and one coin coming up with a head and a six = 1/2 x 1/6 = 1/12 AaRr x AaRr the chance for getting AaRr = 1/2 x 1/2 = 1/4 Thc chance for getting AARr = ? Phenotypic Ratio? (A_R_, A_rr, aaR_, aarr) AaRrCcDd x AarrCcdd AarrCcDd? AARrCcDD?

10. Non-Mendelian patterns of inheritance Incomplete Dominance: Hybrids produce a trait that reveals a blend of both aleles R = red W = white RR = red WW = White RW = Pink Co-Dominance Hybrids reveals trait of both aleles R = red W = white RR = red WW = White RW = Roan (red & white colors)

11. Polygenic inheritance Multiple pairs of genes all influencing one trait Many pairs of genes influence the height of a human. Efficiency of the digestive system, circulatory system, and endocrine system - each being controlled by many pairs of genes - will all impact height. Yao Ming 7’5” Earl Boykins 5’5”

12. Multiple Aleles Traits in which within a population there exists more than two forms of a gene. Human blood type - RBC surface proteins must be compatible when initiating a transfusion. Some people have A proteins on their RBC’s, others have B proteins., and others have neither.Within the human population there exists three forms of the gene that controls surface proteins on RBC’s. Alele A (makes A proteins) Alele B (makes B proteins) Alele i (makes neither A or B) • Four main blood types: (phenotypes) A - B - AB - O • Genotypes: • AA, Ai - blood type A • BB, Bi - blood type B • AB - blood type AB • ii - blood type O Ai x Bi ?

13. Sex Linkage Most animal species have a special pair of chromosomes that determine gender. In humans 22 pairs of autosomes and 1 pair of sex chromosomes Two types - X (large and has genes that control non gender related traits) Y (small and only promotes the formation of male genitalia) XX = female XY = male Sex linked traits are traits controlled by genes on the X chromosome. Females have two, males have only one. Females can carry but not show defective sex linked traits. Males CAN NOT be carriers. XX x XY

14. Duchene’s Muscular Dystrophy Color Blindness Hemophilia

15. Duchene’s Muscular Dystrophy Color Blindness Hemophilia

16. Duchene’s Muscular Dystrophy Color Blindness Hemophilia

17. Duchene’s Muscular Dystrophy Color Blindness Hemophilia

18. Duchene’s Muscular Dystrophy Color Blindness Hemophilia