Gregory Mendel

4. Gregory Mendel • Gregory developed own experiment to study different traits in peas • First scientist to study genetics • “Father of Genetics”

5. Genes • Units of information about specific traits • Passed from parents to offspring • Each has a specific location (locus) on a chromosome

6. Alleles • Different forms of a gene • Each person has at 2 alleles for each trait • 2 types • Dominant (A) • Recessive (a)

7. Must KNOW Vocabulary! Chromosomes-transmitted from one generation to the next, contains many genes Gene- sequence of DNA on the chromosome, determines trait (about 30,000 in humans) Alleles-alternative forms of a gene

8. More Vocab…… • Homozygous-2 copies of allele are the same • AA • aa • Heterozygous- 2 copies of allele are different • Aa

9. And more Vocab….. • Phenotype- what you see • (purple/white) • Genotype- actual alleles present • (PP/Pp/pp)

10. Probability • The chance that an outcome of a given event will occur • Punnett squares give probability for what kinds of offspring will be born…..doesn’t tell EXACTLY how many of each kind you will have • EX: if you flip a coin 10 times, you would predict 5 heads/5 tails. • Is this always true???

11. Mendel’s First Law: Principle of Segregation • Alleles split apart randomly in meiosis

12. Punnett-Square Method • Draw a box • Put genotype at the top, bring alleles down • Put other genotype on the side, bring alleles over

13. Pedigrees • Write lines for all of your individuals • Put in known alleles • Work backwards to solve to missing alleles

14. Tracking Generations • Parental generation (P) • First-generation offspring (F1) • Second-generation offspring (F2)

15. Mendel’s Second Law:Principle of Independent Assortment • Traits don’t always stay together • EX: white/short tail • Brown/long tail Aren’t inherited together!

16. Dihybrid Crosses • Always use to compare the possibility of inheriting 2 different traits • Figure out genotypes of parents • Find all possible allele combinations for their gametes • F.O.I.L.- firsts, outers, inners, lasts • Complete a Punnett Square to solve for offspring

17. Question of the Day • Brown eyes are dominant to blue eyes • Freckles are dominant to no freckles • Mom is heterozygous • Dad is heterozygous

18. Epistasis • One gene can mask the phenotypic effects of a different gene • Results when more than one gene codes for a particular trait • Common among genes for hair color in mammals

20. Black B is dominant to brown b • BB Black • Bb Brown • Yellow the epistasis trait that is only present when homozygous recessive • BE black • bE brown • Ee yellow

21. Pleiotropy • Alleles at a single locus may have effects on two or more traits • Eye color • Skin color

23. A rose breeder finds that when he crosses a true-breeding climber with a true-breeding shrubby plant all F1 offspring are climbers. Find the F2 generation. • He also found that when he crossed sweet smelling roses with no scent roses, all of the F1 plants smelled sweet. Find the F2 generation. • Using the information from above cross a plant that is hetero for BOTH traits with a plant that is hetero for BOTH traits. What does your F1 generation look like?

24. Incomplete Dominance • a cross between individuals with two different phenotypes produces offspring with a third phenotype that is different • Heterozygous genotype displays a different phenotype than either homozygous parent

26. Codominance • a cross between two different phenotypes produces offspring with a third phenotype in which both of the parental traits appear together.  • Heterozygous produces phenotype with both parent’s phenotypes visible • Blood Typing

27. Thorns on roses are controlled by 2 genes. Thorns are dominant to no thorns for the first gene. However the other gene will overshadow the first and will show the phenotype of thorns if a dominant allele is present. • Solve the phenotypes of the offspring if one plant that is hetero for both genes crosses with another plant that is homoz recessive for both genes. • Solve for the possible parents genotypes if there are 3 offspring in the F1 generation, 2 that do not have thorns and the other does have thorns.

28. If you cross a homoz red plant with a white plant all F1 offspring are pink. However if you cross homoz tall plant with a homoz short plant all F1 offspring are tall. • You cross a hetero tall, pink plant with a short, white plant. What are the genotypes and phenotypes of the offspring? • Identify the parents if you haveF1 offspring that are tall/red, short/pink. • What would you cross with a hetero tall pink plant to get offspring that are short and pink? Justify your answer.

29. Homework! • Pg183-185 Genetics Problems • 2, 3, 5, 6, 7, 9,10,12,13,14,

30. Blood Types • Gene that controls ABO type codes for enzyme that dictates structure of a glycolipid on blood cells • Two alleles (IA and IB) are codominant when paired • Third allele (i) is recessive to others

31. Blood Types • IAIA Type A • IBIB Type B • ii Type O • IAi Type A • IBi Type B • IAIB Type AB

32. Blood Transfusions • Recipient’s immune system will attack blood cells that have an unfamiliar glycolipid on surface • Type O is universal donor because it has neither type A nor type B glycolipid

33. 48.Mom is type A and has a child that is type O, what is/are dads possible blood type/s? 49.If mom is hetero type B and dad is hetero A, what is/are the possible blood types of the offspring going to be? 50.Which blood type is recessive to the other types? Answers: a. Type A, Type B, Type AB b. Type A, Type B, Type O c. Type AB d. Type O e. All of these

34. Linkage and Cross-over • Each chromosome becomes zippered to its homologue • All four chromatids are closely aligned • Non-sister chromosomes exchange segments

35. Effects of Crossing Over • After crossing over, each chromosome contains both maternal and paternal segments • Creates new allele combinations in offspring

37. Linkage Groups 1. Two or more genes can be located on the same chromosome 2. Genes that are close together tend to be transmitted as a unit but not all genes are transmitted together

38. Crossover Frequency • Proportional to the distance that separates genes

39. Pedigree Analysis • Genetic Abnormality: A rare uncommon version of a trait • polydactyly • Genetic Disorder: Inherited conditions that cause mild to severe medical problems • Why don’t they disappear? • Mutation introduces new rare alleles • In heterozygotes, harmful allele is masked, so it can still be passed on to offspring

40. Symbols in Predigrees

41. Phenotypic Treatments • Symptoms of many genetic disorders can be minimized or suppressed by • Dietary controls • Adjustments to environmental conditions • Surgery or hormonal treatments

42. Genetic Screening • Large-scale screening programs detect affected persons • Newborns in United States routinely tested for PKU • Early detection allows dietary intervention and prevents brain impairment

43. Prenatal Diagnosis • Amniocentesis • Chorionic villus sampling • Fetoscopy • All methods have some risks

44. Preimplantation Diagnosis • Used with in-vitro fertilization • Mitotic divisions produce ball of 8 cells • All cells have same genes • One of the cells is removed and its genes analyzed • If cell has no defects, the embryo is implanted in uterus

45. Question of the Day • Identify what type of dominance is happening here and justify your reasoning

46. Identify what type of dominance is happening here and justify your reasoning

47. Karyotype Preparation: • Stopping the Cycle: • Cultured cells are arrested at metaphase by adding colchicine • This is when cells are most condensed and easiest to identify

48. Karyotype Preparation • Arrested cells are broken open • Metaphase chromosomes are fixed and stained • Chromosomes are photographed through microscope • Photograph of chromosomes is cut up and arranged to form karyotype diagram

50. Karyotype Diagram