Bell Ringer

1. Bell Ringer • Look at your classmates. Note how they vary in the shape of the front hairline, the space between the two upper front teeth, and the way in which the earlobes are attached. • Make a list of the different forms of these traits that you have observed in the class or among other people you know. • Could these traits be inherited? From whom could they be inherited? • How is it possible that these traits could be found in a person and his or her biological grandparents but not in the biological parents?

2. Bell Ringer • Could these traits be inherited? From whom could they be inherited? • How is it possible that these traits could be found in a person and his or her biological grandparents but not in the biological parents?

3. Bell Ringer • Could these traits be inherited? From whom could they be inherited? • Yes; from parents. • How is it possible that these traits could be found in a person and his or her biological grandparents but not in the biological parents? • Genes are passed from generation to generation, but are not necessarily expressed in every generation. 3. Every living thing – plant or animal, microbe or human being – has a set of characteristics inherited from its parents.

4. Genetics

5. Gregor Mendel • In 1865, GregorMendel published studies of inheritance in pea plants. • During sexual reproduction, male and female gametes join to form a zygote in the process known as fertilization. • Genetics= the scientific study of heredity.

6. Heredity is… the passing on of traits from parents to offspring. • Controlled by “factors.” • Passed from generation to generation. • Probability • Traits – characteristics that are inherited.

7. 1902 – Chromosome Theory of Heredity • Genes (Mendels “factors”) are located on chromosomes. • The different forms of a gene are called Alleles. • This is the basis for the modern science of Genetics.

8. Genetic Principles 1. Alleles – gene form, Y or y, for each variation of a trait of an organism. 2. Dominance and Recessiveness D= visible, observable trait of an organism that masks a recessive form of a trait. R = a hidden trait of an organism that is masked by a dominant gene. • Separation, or Segregation • Independent Assortment

9. Other Terms • Phenotype – the way an organism looks and behaves. Physical characteristics of an organism. • Genotype – the gene combination of an organism. • Homozygous – when an organisms two alleles for a trait are the same. • Heterozygous – when an organisms two alleles for a trait are not the same.

10. Genes VS Alleles

11. Genes VS Alleles

12. R.C. Punnett • In 1905, R.C. Punnett introduced the Punnett square. • Punnett squares can be used to predict and compare the genetic variations that will result from a cross

13. Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype: YY xyy Phenotype: Yellow x green

14. Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype: YY xyy Phenotype: Yellow x green

15. Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype: YY xyy Phenotype: Yellow x green

16. Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype: YY xyy Phenotype: Yellow x green

17. Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype: YY xyy Phenotype: Yellow x green

18. Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype: YY xyy Phenotype: Yellow x green

19. Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype: YY xyy Phenotype: Yellow x green

20. Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype: YY xyy Phenotype: Yellow x green

21. Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype: YY xyy Phenotype: Yellow x green

22. Using Punnett Squares Yellow pea seed (Y) is DOMINANT to green (y). Genotype: YY xyy Phenotype: Yellow x green All (100%) offspring in F1 Generation are Yellow hybrids.

23. Monohybrid Cross Yy x Yy Yellow x Yellow

24. Monohybrid Cross Genotype: Yy x Yy Phenotype: Yellow x Yellow

25. Monohybrid Cross Genotype: Yy x Yy Phenotype: Yellow x Yellow

26. Monohybrid Cross Genotype: Yy x Yy Phenotype: Yellow x Yellow

27. Monohybrid Cross Genotype: Yy x Yy Phenotype: Yellow x Yellow

28. Monohybrid Cross Genotype: Yy x Yy Phenotype: Yellow x Yellow

29. Monohybrid Cross Genotype: Yy x Yy Phenotype: Yellow x Yellow

30. Monohybrid Cross Genotype: Yy x Yy Phenotype: Yellow x Yellow

31. Monohybrid Cross Genotype: Yy x Yy Phenotype: Yellow x Yellow

32. Monohybrid Cross Genotype: Yy x Yy Phenotype: Yellow x Yellow

33. Monohybrid Cross Genotype: Yy x Yy Phenotype: Yellow x Yellow Phenotypic Ratio: 75% (3/4) offspring are Yellow; Ratio is 3:4 (Yellow : total) 25% (1/4) offspring are green; Ratio is 1:4 (green : total)

34. Dihybrid Cross • Round pea seed (R) is dominant to wrinkled pea seed (r). • FOIL: YyRrYR, Yr, yR, yr • (These are the possible genotypic combinations)

35. Dihybrid Cross Round pea seed (R) is dominant to wrinkled pea seed (r).

36. Dihybrid Cross Round pea seed (R) is dominant to wrinkled pea seed (r).

37. What is the probability that the plant will produce: Yellow, Round Peas: Yellow, Wrinkled Peas: Green, Round Peas: Green, Wrinkled Peas:

38. What is the probability that the plant will produce: Yellow, Round Peas: 9/16 Yellow, Wrinkled Peas: 3/16 Green, Round Peas: 3/16 Green, Wrinkled Peas: 1/16

39. Incomplete Dominance – When one allele is not completely dominant over another and the heterozygous genotype becomes the phenotype • Example: Red flowers (RR) crosses with white flowers (WW) shows incomplete dominance for pink flowers (RW)

40. Codominance – when both alleles contribute to the phenotype. Example – black feathers codominant with white feathers in chickens, both white and black feathers are present separately. Also blood types and a cholesterol enzyme in humans.

41. Multiple alleles-genes that have more than 2 alleles • This means that there are more than 2 possible alleles in a population • Example: rabbit fur colors • Polygenic traits – traits controlled by more than 2 genes • Example: human skin color is controlled by more than 4 different genes