1. Honors Biology Ch. 10 Sexual Reproduction and Genetics

2. - one member of a pair comes from each parent I.Meiosis A.Homologous Chromosomes: - pairs of chromosomes that are very similar

3. B.Diploid: - a full set of homologous chromosomes (2n) - in humans: 46 (23 pairs) - in pea plants: 14 (7 pairs)

4. Human Chromosomes (23 homologous pairs)

5. C.Haploid: -a half set of chromosomes (1n) -occur in Gametes (specialized reproductive cells: sperm and egg)

6. D.Process of Meiosis: -specialized cell division in which the chromosome number is cut in half -homologous pairs of chromosomes are separated -produces haploid gametes -occurs in 2 stages:

7. 1.Meiosis I: a)similar to mitosis, but, during metaphase, homologous chromosomes come together to form a tetrad b)Crossing-over occurs: exchange of genes between homologous chromosomes c)The homologous chromosomes separate during anaphase I. c)2 cells are produced that contain 1 replicated chromosome from each homologous pair.

8. Meiosis I Homologous chromosomes pair and cross over Homologous chromosomes exchange DNA & align on equator Homologous chromosomes move to opposite poles I Prophase I Metaphase I Anaphase I Telophase I

9. red Purple round Long P P p p LLl l P p p LLl l PLp L l lPp P L p L l l P p LL l lPP p p P P p p L L l l P p p L L l l Crossing Over Sister Chromatids Replicated Chromosome LL l lPP p p Sister Chromatids Homologous Chromosomes P P p p LLl l P p p LLl l pL Pl LP lp old combination new combination old combination Flower Color Pollen Shape

10. Chiasmata Crossing-over in a tetrad of a grasshopper. Each cross-over is called a chiasma. This example shows 5 chiasmata.

11. 2.Meiosis II: a)similar to mitosis but DNA replication does not occur before division b)Sister chromatids separate during anaphase II. c)4 haploid daughter cells are produced

12. Meiosis II Prophase II Metaphase II Anaphase II Telophase II Four Haploid Cells

13. Spermatogenesis Oogenesis Spermatogonia Primary Spermatocyte Secondary Spermatocytes Spermatids Spermatozoa Primordial Germ Cells Mitosis Meiosis Oogonia Primary Oocyte Secondary Oocyte & Polar Body Ovum & Polar Body Unequal division of cytoplasm produces oocytes and polar bodies.

14. E.Importance of Meiosis: - provides genetic variation in the next generation 1. Independent Assortment - chromosomes randomly separate during meiosis - results in gametes with different combinations of chromosomes - for pea plants, 2 7 = 128 different combinations

15. The Independent Assortment of Homologous Chromosomes in Meiosis Key Maternal set of chromosomes Paternal set of chromosomes Possibility 1 Two equally probable arrangements of chromosomes at metaphase I Possibility 2 Metaphase II Daughter cells Combination 1 Combination 2Combination 3Combination 4

16. 2.Crossing over - produces recombined chromosomes that carry genes derived from two different parents

17. The Results of Crossing over During Meiosis Prophase I of meiosis Nonsister chromatids Tetrad Chiasma, site of crossing over Metaphase I Metaphase II Daughter cells Recombinant chromosomes

18. 3.Random Fertilization - combines chromosomes from 2 parents - results in over 70 trillion possible combinations of genes from any 2 parents

19. II. Mendel’s Laws of Heredity Heredity: -the passing of traits from parent to offspring Genetics: -the study of heredity

20. Early Idea about Genetics Homunculus

21. A.Gregor Mendel: -father of genetics -Austrian monk -developed the basic principles of Heredity (1880's)

22. B.Mendel’s Experiments 1.Used garden peas -several crops per year -small, fast growing -developed "purebreds"

23. - easy to control pollinate Pea Flower Pea Flower Stamens (male) produce pollen Pistil (female) produces eggs

24. - seven distinct, inherited traits Plant size Flower location Flower color Pod color Pod shape Seed shape Seed color

25. 2.Used math and statistics to support theories 3.Published results in 1859 - rejected by academic peers - in 1900 his work was rediscovered

26. PF1F1

27. F1F1 F2F2

28. III.Principles of Heredity A.Concept of Unit Characters: - traits are controlled by "factors" (genes) which occur in pairs - one from each parent

29. B.Principle of Dominance and Recessiveness: - some alleles dominate, or mask, the effect of other alleles - Allele: one of the "versions" of a gene

30. C.Law of Segregation: -during meiosis (production of gametes), each pair of genes separate

31. Cross Fertilization of Parents Purebred (Homozygous) Purple-flowered Parent Purebred (Homozygous) White-flowered Parent Cross-Fertilize All Purple- flowered (Heterozygous) Offspring Pollen PP pp P P p p Pp

32. F1F1 Self-Fertilize F2F2 F2F2 F2F2 F2F2 75% Purple 25% White Self-fertilization of F 2 Pp PP Pp pp

33. 1.Gametes: - specialized, reproductive cells (sperm, egg) - have 1/2 a set of chromosomes

34. 1.Gametes: 2.Genotype: - genetic make-up of an organism 3.Phenotype: - physical appearance of an organism - specialized, reproductive cells (sperm, egg) - have 1/2 a set of chromosomes

35. 4.Homozygous: - alleles in a gene pair that are identical - TT or tt TTTttt 5.Heterozygous: -alleles in a gene pair that are different - Tt

36. D.Principle of Independent Assortment: -alleles separate randomly during meiosis

37. IV.Applying Mendel‘s Principles A.Probability: -the likelihood that an event may happen

38. B.Rules of Probability: 1.Product Rule of Probability: -when events occur in combination, the probability of each event is multiplied by the probability of the other 1/2 x x = 1/8 What are the odds of rolling 3 tails in a row?

39. Cystic FibrosisF = Normal f = cystic fibrosis 1 out of 25 are heterozygous in UK Odds of any heterozygous man and woman marrying = 1/25 x 1/25 = Odds of a heterozygous man and woman having a child with cystic fibrosis = 1/625 x 1/4 =

40. 2.Probability has No Memory: -Previous events do not influence the probability of future events What are the odds on the next toss being a tail? 1/2 The odds of rolling 3 tails in a row are 1/8.

41. V.Gene Linkage and Polyploidy A.Gene Linkage - Chromosomes contain thousands of genes. - Genes are physically linked together on a chromosome. -During crossing over this linkage can be broken temporarily. - Frequency of crossing over can be used to make chromosome maps.

42. V.Gene Linkage and Polyploidy A.Gene Linkage

43. V.Gene Linkage and Polyploidy A. Gene Linkage

44. B.Polyploidy - The occurrence of one or more extra sets of all chromosomes in an organism.

45. B.Polyploidy - The occurrence of one or more extra sets of all chromosomes in an organism. - Rare in animals but occurs commonly in plants. - Produces new plant varieties

46. Coffee beans, 4n = 44 Banana, 3n = 33 Cotton, 4n = 52 Potatoes, 4n = 48 Corn, 4n = 20 Canola oil, 4n = 38 Bread wheat, 6n = 42 Rope from sisal, 5n = 180 A Sample of Agricultural Crops That Are Polyploid

47. The Evolution of Wheat

48. The End

49. 3.When an event can happen in more than one combination, the probability of the event is the sum of the probability of each. OR 1/4 What are the odds of getting ‘a head and a tail’ any order? + 1/4 = 1/2