1. Genetics: The Work of Gregor Mendel Objectives The principle of dominance states that some alleles are dominant and other are recessive. The principle of segregation. Homework Section Assessments 11-1 and 11-2 due Thursday (loose- leaf/all questions) Probability Lab Due Thursday as well Quiz Friday!! –Mendel & Punnett Squares Do now!! –What is the probability of flipping a coin and getting…

2. Genetics: The Work of Gregor Mendel Objectives Some genes are linked to the X chromosome in a sex-linked inheritance pattern. Some genes are located on the same chromosome preventing them from assorting independent from one another. Do now!! Create a concept map on the topics of Genetics!!

3. Fig. 14-1 The “particulate” hypothesis is the idea that parents pass on discrete heritable units (genes) The “blending” hypothesis is the idea that genetic material from the two parents blends together (like blue and yellow paint blend to make green)

4. Some vocab for ya!!!!! Trait - specific characteristic that varies from one individual to another Gene - sequence of DNA that codes for a protein and thus determines a trait Allele - one of a number of different forms of a gene Hybrid - offspring of crosses between parents with different traits The principle of dominance states that some traits are dominant and others are recessive.

5. Some more vocab for ya!!! Homozygous - term used to refer to an organism that has two identical alleles for a particular trait Heterozygous - term used to refer to an organism that has two different alleles for the same trait Phenotype - physical characteristics of an organism Genotype - genetic makeup of an organism

6. Genetics: The Work of Gregor Mendel Objectives The principle of dominance states that some alleles are dominant and other are recessive. The principle of segregation. Do now!! What does it mean for an organism to be true-breeding? How did Mendel ensure that he had true-breeding pea plants? Why was it vital for Mendel to have true- breeding pea plants?

7. Gregor Mendel – Father of Modern Genetics True-breeding - term used to describe organisms that produce offspring identical to themselves if allowed to self- pollinate.

8. The work of Mendel Mendel had true- breeding pea plants. He asked the question: What would happen if he breed pea plants with different traits?

9. Dominant and Recessive Traits & Gregor Mendel’s Peas P – Parent generation F1 – first generation of offspring (f – filial from latin filius “son”)

10. Punnett Square diagram showing the gene combinations that might result from a genetic cross Cross YY and yy YY yYy y

11. Crossing true-breeding parent generation Trait –Green pea –recessive Genes (alleles) –yy Gametes formed –y and y Trait –Yellow pea –dominant Genes (alleles) –YY Gametes formed –Y and Y Cross YY and yy YY yYy y P Generation F1 Generation

12. Crossing the F1 generation Trait –Yellow pea Genes (alleles) –Yy Gametes formed –Y and y Trait –Yellow pea Genes (alleles) –Yy Gametes formed –Y and y Cross Yy and Yy Yy YYYYy y yy F1 Gen. F2 Generation

13. Probability and Genetics Probability - likelihood that a particular event will occur Cross YY and yy Yy YYYYy y yy

14. Genotypes and Phenotypes Phenotypes and Genotypes Although these plants have different genotypes (TT and Tt), they have the same phenotype (tall).

15. Genetics: The Work of Gregor Mendel Objectives Principle of Dominance Principle of segregation The Principle of independent assortment. Homework Quiz on Mendel tomorrow. (Dihybrid cross will be extra credit) Do Now What is segregation? What happens to alleles during segregation?

16. Using ratios from Punnett Squares Ratio of tall to short pea plants is 3:1 If we breed heterzygous tall pea plants with each other and in one generation we made 1000plants, How many tall pea plants and short pea plants should we have?

17. What are the ratios for genotype and phenotype? Genotype ratio - 1:2:1 –1 HoZ tall, 2 HeZ, 1 HoZ short Phenotype ratio – 3:1 –3 tall pea plants, one short pea plant Cross Tt and Tt Tt TTTTt t tt

18. Crossing the F1 generation Segregation - separation of alleles during gamete formation When each F1 plant flowers, the two alleles are segregated from each other so that each gamete carries only a single copy of each gene. Therefore, each F1 plant produces two types of gametes— those with the allele for tallness and those with the allele for shortness.

19. Law of Independent Assortment The principle of independent assortment states that genes for different traits can segregate independently during the formation of gametes. In other words, genes (alleles) of different traits separate independent of one another. Genes (alleles) of one trait do not affect genes of another trait. This allows us to cross genes for different traits at the same time.

20. Cross of heterozygous yellow and round peas. First, what is the genotype of the parents? Second, how many different gametes can be formed? Third, what are the different gametes? RYRyrYry Parent: RrYy

21. Cross of heterozygous yellow and round peas. How many different phenotypes do we have? –4 What is the ratio for the phenotypes? –9:3:3:1

22. Homework In your notebook – –Cross two heterzygous tall/green pod pea plants with each other. –What is the phenotype ratio? –If you had 50,000 offspring how many should you have for each phenotype?

23. Summary of Mendel’s Principles The inheritance of biological characteristics is determined by individual units known as genes. In organisms that reproduce sexually, genes are passed from parents to their offspring. In cases in which two or more forms of the gene for a single trait exist, some forms of the gene may be dominant and others may be recessive. In most sexually reproducing organisms, each adult has two copies of each gene—one from each parent. These genes are segregated from each other when gametes are formed. The alleles for different genes usually segregate independently of one another.

24. Quiz tomorrow Chapter 11 Cross two pea plants one is heterozygous for green pod and tall plant the other is homozygous for green pods and heterozygous for tall Give me the ratio of the phenotypes

25. Beyond dominant and recessive alleles. Most genes do not follow the simple patterns of dominant and recessive alleles. Some alleles are neither dominant nor recessive, and many traits are controlled by multiple alleles or multiple genes.

26. 1. List the four basic principles of genetics that Mendel discovered in his experiments. Briefly describe each of these principles. 2. What is probability? How does probability relate to genetics? 3. In pea plants, the allele for yellow seeds is dominant to the allele for green seeds. Predict the genotypic ratio of offspring produced by crossing two parents heterozygous for this trait. Draw a Punnett square to illustrate your prediction. 4. Designing Experiments In sheep, the allele for white wool (A) is dominant over the allele for black wool (a). How would you determine the genotype of a white ram, or male sheep? 5. Inferring Suppose Mendel crossed two pea plants and got both tall and short offspring. What could have been the genotypes of the two original plants? What genotype could not have been present? 6. Applying Concepts In guinea pigs, the allele for a rough coat (R) is dominant over the allele for a smooth coat (r). A heterozygous guinea pig (Rr) and a homozygous recessive guinea pig (rr) have a total of nine offspring. The Punnett square for this cross shows a 50 percent chance that any particular offspring will have smooth coats. Explain how all nine offspring can have smooth coats.

27. Genetics: The Work of Gregor Mendel Objectives Beyond Mendelian Genetics Homework Do Now Cross YyTtSs x YyTtSs What is the chance of getting a Yellow Seed, short pea plant with constricted pea pods? What is the chance of getting a green seed, short pea plant, with constricted pea pods? What is the chance of getting a Yellow seed, tall pea plant with smooth pea pods?

28. Beyond dominant and recessive alleles incomplete dominance - situation in which one allele is not completely dominant over another There is no white no red: new phenotype pink

29. Beyond dominant and recessive alleles Codominance - situation in which both alleles of a gene contribute to the phenotype of the organism

30. Beyond dominant and recessive alleles multiple alleles - three or more alleles of the same gene

31. Beyond dominant and recessive alleles polygenic trait - trait controlled by two or more genes

32. Genetics: The Work of Gregor Mendel Objectives Some genes are linked to the X chromosome in a sex-linked inheritance pattern. Some genes are located on the same chromosome preventing them from assorting independent from one another. Do now!! Take out your handout from Friday and prepare to go over it.

33. Chromosome Theory of Inheritance Mendelian genes have specific loci along chromosomes, and it’s the chromosomes that undergo segregation and independent assortment.

34. Thomas Hunt Morgan First to associate a specific gene with a specific chromosome Drosophila melanogaster = fruit fly

35. Fruit Flies Wild type = normal character phenotype Mutant = alternative traits Morgan’s cross: –White-eyed male with a Red-eyed female –All the F 1 offspring had red eyes –What would you conclude? The red allele is dominant to the white allele

36. But then… Crosses between F 1 offspring produced 3:1 phenotypic ratio in F 2 offspring The white-eyed trait appeared only in males Morgan concluded that a fly’s eye color was linked to its sex

37. sex-linked gene The gene with the white-eyed mutation is on the X chromosome

38. Thomas Hunt Morgan’s Lab!!! Alfred Sturtevant

39. Genetic recombination Parental types = phenotypes that match the original parents Recombinants = new combination of parental traits dihybrid cross  combination of traits that did not match either parent –crosses between hybrid plants produces four phenotypes

40. body color and wing shape are usually inherited together because their genes are on the same chromosome

43. linkage map used recombination frequencies from fruit fly crosses to map the relative position of genes along chromosomes frequency of recombinant offspring reflected the distances between genes on a chromosome

44. map units One map unit is equivalent to a 1% recombination frequency

45. Linkage and Gene Maps It’s easy to see how genes located on different chromosomes assort independently, but what about genes located on the same chromosome? Wouldn’t they generally be inherited together? Thomas Hunt Morgan’s studies back in 1910 helped us to answer this question.

46. Linkage and Gene Maps Just because two genes are located on the same chromosome does not mean that they are linked together forever. Crossing-over Also, the further apart they are the more likely they are to separate. The closer they are the less likely they are to separate.

47. Sex-Linked Inheritance and Pedigree Charts Objective Discuss the inheritance pattern of sex-linked recessive traits. Analyze a pedigree to determine the inheritance pattern of a trait. Do Now In fruit flies, the genes for wing shape and body stripes are linked. In a fly whose genotype is WwSs, W is linkd to S and w in linked to s. Show how this fly can produce gametes containing four different combination of alleles. Which are parental type gamets? Which are recombinant gametes? How are the recombinant produced?

48. Sex-Linked Genes Males have just one X chromosome. Thus, all X-linked alleles are expressed in males, even if they are recessive.

49. Pedigree Analysis A pedigree is a family tree that describes the interrelationships of parents and children across generations Inheritance patterns of particular traits can be traced and described using pedigrees Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings

50. Fig. 14-15b 1st generation (grandparents) 2nd generation (parents, aunts, and uncles) 3rd generation (two sisters) Widow’s peakNo widow’s peak (a) Is a widow’s peak a dominant or recessive trait? Wwww Ww ww Ww wwWW Ww or

51. Fig. 14-15c Attached earlobe 1st generation (grandparents) 2nd generation (parents, aunts, and uncles) 3rd generation (two sisters) Free earlobe (b) Is an attached earlobe a dominant or recessive trait? Ff ffFf ff FFor FF Ff

52. Autosomal Disorders Genes for these disorders are located on autosomes –Recessive disorder –Dominant disorders –Codominant disorders

53. (Start Next)The Behavior of Recessive Alleles Recessively inherited disorders show up only in individuals homozygous for the allele Carriers are heterozygous individuals who carry the recessive allele but are phenotypically normal (i.e., pigmented) Albinism is a recessive condition characterized by a lack of pigmentation in skin and hair Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings

54. Fig. 14-16 Parents Normal Sperm Eggs Normal (carrier) Normal (carrier) Albino Aa A A AA Aa a aa a 

55. Cystic Fibrosis

56. Fig. 14-17 Eggs Parents Dwarf Normal Dwarf Sperm Dd  dd d D Dd dd Dd d d

58. Multifactorial Disorders Many diseases, such as heart disease and cancer, have both genetic and environmental components –Little is understood about the genetic contribution to most multifactorial diseases Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings

59. Genetic Testing and Counseling Genetic counselors can provide information to prospective parents concerned about a family history for a specific disease Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings

60. Fig. 14-18 Amniotic fluid withdrawn Fetus Placenta Uterus Cervix Centrifugation Fluid Fetal cells Several hours Several weeks Several weeks (a) Amniocentesis (b) Chorionic villus sampling (CVS) Several hours Several hours Fetal cells Bio- chemical tests Karyotyping Placenta Chorionic villi Fetus Suction tube inserted through cervix