Heredity

1. Heredity

2. Chapter 10Patterns of Inheritance

3. Observations?

4. 10.1 Curiosity about Inheritance • The “Blending” Hypothesis • Early 1800s thought… • If you mix red + yellow = orange • Same idea for hereditary information? • BUT?! • How do you explain getting “reds” and “yellows” • Second generation offspring not all orange *Did not explain how traits that disappear in one generation can reappear in later ones!

5. Gregor Mendel • First to apply an experimental approach to inheritance questions • Gregor’s experiment • 7 years bred pea plants and recorded inheritance patterns of offspring • Formed the Particulate Hypothesis • Parents pass on to their offspring separate and distinct factors (?) that are responsible for inherited traits

6. Mendel’s Experiment • 1- Identify true-breeding plants • White plants ONLY Purple plants ONLY • 2-Cross 2 different true-breeding plants • 3- Those offspring become parents for next generation breeding (cross fertilization) • 4- Observed the patterns of inheritance • What colors were in the next generation?

7. 10.2 Inheritance’s Rules of Chance Terminology: • Parents = P generation • Hybrid offspring = F1 generation • Offspring of 2 different true-breeding varieties are “hybrids” • F1 plants self-fertilize or fertilize each other their offspring = F2 generation

8. Generations… What Mendel Saw….

9. Inheritance’s Rules of Chance • Monohybrid Cross (he did this w/o calling it this) • 1 trait (color) • Each produced same pattern • Mendel Saw 1 of the 2 traits disappears in F1 and then reappeared in ¼ of F2 Caused Mendel to form 4 hypotheses…

10. Mendel’s Hypotheses • 1. Alternating forms of genes called alleles • Genotype = letters (AA, Aa, aa) • Phenotype = observe (purple, white)

11. Mendel’s Hypotheses 2. For each trait organism has 2 alleles • Same 2 alleles = homozygous (AA, aa) • Different alleles = heterozygous (Aa)

12. Mendel’s Hypotheses 3. When only 1 of the 2 traits in a heterozygous organisms is visible the allele is dominant (R) thenon visible is recessive (r)

13. Mendel’s Hypotheses 4. The 2 alleles for a character separate during meiosis (gametes) Principle of segregation!!

14. Monohybrid crosses P = Purple (dominant) p = white (recessive)

15. Punnett Squares • Calculate probabilities/outcomes of a genetic cross • Genotype genetic makeup • Phenotype observable trait • Manipulate genotypes that then show the phenotypes • Phenotypic ration 3:1 • Genotypic ratio 1PP: 2Pp: 1pp

16. Cross H. Dominant X Heterozygous RR X Rr R R If R= Hairy r = smooth What will the offspring look like? (phenotype) What are the genotypes? R r

17. Cross H. Recessive X Heterozygous If R= Hairy r = smooth What will the offspring look like? (phenotype) What are the genotypes?

18. Cross Heterozygous X Heterozygous If R= Hairy r = smooth What will the offspring look like? (phenotype) What are the genotypes?

19. Cross H. Dominant X H. Recessive If R= Hairy r = smooth What will the offspring look like? (phenotype) What are the genotypes?

20. Question If Delani has brown eyes and Mihir has brown eyes what are their genotypes? A = brown and a = blue

21. Test Cross • Possible genotype for • PurplePP Pp • White pp How do you know if you have PP or Pp? • Test Cross!!!! • Cross your unknown with homozygous recessive

22. Testcross When an individual with a dominant phenotype whose genotype is unknown breeds with a homozygous recessive individual. X BB or Bb? bb

23. X If BB, then: If Bb, then B B B b b b b b 50% 50% All black eyes

24. Test Cross • If the unknown individual is Homozygous dominant all the offspring will show the dominant characteristic X BB X bb B B b b All black eyes

25. Test Cross • If the unknown individual is heterozygous dominant half the offspring will show the dominant characteristic and half will show the recessive characteristic. X Bb X bb B b b b 50% 50%

26. Questions • Otis Oompah has an orange face and is married to Ona Oompah who has a blue face. They have 60 children, 31 of them have orange faces. What are the genotypes of the parents.

27. Oompahs generally have a blue face which is caused by a dominant gene. The recessive condition results in an orange face. • A blue faced Oompah (homozygous) is married to an orange faced Oompah. How many children will have blue faces?

28. Cross a Hetero for tall with Hetero for Tall • T = tall • t = short • Tt X Tt 

29. In fat orange cats being striped is dominant to being solid orange. What could you do to determine if Garfield is heterozygous or homozygous for his strips if you did not know???

30. Dihybrid Crosses • Crossing individuals differing in 2 characteristics

31. Sample DiHybrid Janet has a homozygous recessive short, heterozygous seeded plant. Alice has a heterozygous for height, homozygous recessive wrinkled-seeded plant. If they were to breed their plants together what would be the outcome of the offspring? What are the offspring genotypes, phenotypes and ratios? (T=tall, t=short R=rounded seed, r = wrinkled seed) Janet : ttRr Alice: Ttrr starting genotypes

32. Janet’s Genotype R Alic’s Genotype t t r T t r r

33. Key to Punnett Squares • LABEL EVERYTHING • CHECK YOUR RATIOS

34. Homozygous Dominant = AA • Heterozygous = Aa • Homozygous Recessive = aa • Letters = genotype (AA, Aa, aa) • What you see = phenotype ( color, height)