1. Introduction to Genetics Chapter 9

2. Heredity Transmission of characteristics form parents to offspring

3. Gregor Mendel Austrian Monk Studied heredity in pea plants Studied 7 characteristics of peas

4. Traits characteristic occur in two forms

5. 7 Characteristics of Pea Plants Plant height (long or short) Flower Position along the stem (axial or terminal) Pod Color (green or yellow) Pod appearance (inflated or constricted)

6. Seed texture (smooth or wrinkled) Seed color (yellow or green) Flower color (purple or white)

10. Chromosomes Humans have 46 chromosomes arranged in 23 pairs (44 autosomes and 2 sex chromosomes) Chromosomes are made up of DNA and Proteins Chromosomes and therefore the DNA can be divided into genes Genes are short segments of DNA

11. Chromosome with genes

14. Allele – alternate form of a gene Example: Brown/blue, tall/short can be represented by a letter Example: Brown – B Blue - b

15. Homologous Chromosomes Genes Determines eye color Determines hair color

16. bb bB Blue Allele Brown Allele Blue Alleles One pair of your chromosomes for eye color One pair of your chromosomes for eye color

17. bb bB Blue Allele Brown Allele Blue alleles Homozygous – alleles are the sameHeterozygous – alleles are different

18. Homozygous (pure) The two alleles are the same The two letters are the same BB or bb Homozygous Dominant – BB Homozygous Recessive - bb

19. Heterozygous (hybrid) The two alleles are different The two letters are different Bb

20. Dominant Gene A gene that will be expressed if it is present Examples – brown, tall, green, purple Written as a capital letter

21. Recessive Gene A gene that will only be expressed if there are two alleles present Recessive genes are not expressed if there is a dominant gene present Short, blue, yellow, white Written as a lower case letter

22. Genotype The two alleles an organism has What the genes “say” Ex. BB, Bb, bb

23. Phenotype Physical appearance of an organism The result of the expression of the genes Example: tall, short, brown, blue

24. The Goal The goal of genetics is to determine the possible offspring that can be produced from two parents The likelihood of an outcome is determined through the laws of probability

25. Probability The likelihood that a specific event will occur Can be expressed as a decimal, percent or a fraction

26. Equation for Probability Probability = Number of times an event is expected to happen The number of opportunities for an event to happen

27. Probability Example You flip a coin once The probability of getting tails is ½ You flip a coin twice The probability of getting tails twice is 1/4 1 2 1 2 X = 1 4

28. H T First Flip or Second Flip If I got Tails on the first flip I can either get heads or tails On the second flip T H

29. H T T H H T First Second Probability of getting: 1/4

30. Gametes Egg or sperm Haploid Contains half the number of chromosomes One gene from each homologous pair

32. Genetic Crosses When doing genetic crosses it is important to keep tract of the generations P1 – parents F1 – children of the parents (P1) F2 – Children of the F1’s

33. GG gg Gg GG gg Gg

34. A Genetic Cross Punnett Square – used to predict the possible outcomes of a cross

35. AA aa aa Male produces one type of sperm with the gene A Female produces one type of egg with the gene a

36. The Baby Elephants will be.. Aa

37. Monohybrid Cross Aa A A a a

38. How to fill in the Punnett Square

39. Monohybrid Cross Cross where one trait is looked at Dark elephant vs. light elephant

40. Aa Male produces two types of sperm with the gene A or a Female produces two type of eggs with the gene A or a Aa

41. The Baby Elephants will be.. AA Aa aa

43. Genotypic Ratio Ratio of the offspring's genotypes Genotypic Ratio: 1:2:1 EE – 1 Ee – 2 ee – 1

44. Phenotypic Ratio Ratio of the offspring's phenotypes Phenotypic ratio: 3:1 3 – smooth 1- wrinkled

45. Genotypic Ratio? Phenotypic Ratio? Phenotypes? Genotypes?

46. Law of Segregation A pair of genes is segregated or separated during the formation of gametes

47. Law of Independent Assortment Genes for different characteristics are not connected They are inherited independently

48. Dihybrid Cross A cross between individuals that involves two pairs of contrasting traits Look at hair color and eye color at the same time Look at height and color at the same time

49. Dihybrid Cross Punnett Square

50. AABB aabb AB ab

51. AB ab AB ab AaBb Genes in the fertilized egg Fertilization Egg Sperm

52. AaBb AB ab

53. AaBb Genotypic Ratio: 1 Phenotypic Ratio: 1

54. What if the Dihybrid cross has heterozygous parents? How do you find the gametes?

55. A a B b B b AB Ab aB ab How to find genes for the gametes of a dihybrid cross

56. AaBb AB Ab aBab aB AbAB

60. Dihybrid Heterozygous Cross Genotypic Ratio 1:2:1:2:4:2:1:2:1

61. Testcross When an individual of unknown genotype is crossed with a homozygous recessive individual B? x bb