Section 1: Meiosis

2. Chapter 10 Sexual Reproduction and Genetics Section 1: Meiosis Section2: Mendelian Genetics Section 3: Gene Linkage and Polyploidy

3. Vocabulary *Gene- segments of DNA located on chromosomes that control inherited traits; passed on from one generation to another generation Gene

4. *Chromosome - DNA containing structure that carries genetic material from one generation to another

5. Homologous chromosomes - One of two paired chromosomes, one from each parent, that carries genes for a specific trait at the same location

6. *Synapsis - the pairing of homologous chromosomes during meiosis

7. *Crossing over - Exchange of chromosomal segments between a pair of homologous chromosomes during prophase 1 of meiosis

8. *Gamete - A haploid sex cell, formed during meiosis, that can combine with another haploid sex cell and produce a diploid fertilized egg; egg or sperm *Haploid - Cell with half the number of chromosomes (n) as a diploid (2n) cell Cell with half the number of chromosomes (n) as a diploid (2n) cell n - Used to represent the number of chromosomes in a gamete; haploid

9. *Meiosis - Reduction division process, occurring only in reproductive cells, in which one diploid (2n) cell produces four haploid (n) cells that are not genetically identical

10. *Fertilization - Process by which haploid gametes combine, forming a diploid cell with 2n chromosomes, with n chromosomes from the female parent and n chromosomes from the male parent

11. *diploid - A cell that contains both sets of homologous chromosomes; represented by 2n 2n - Results after fertilization; n chromosomes from female parent and n chromosomes from the male parent; diploid

12. Asexual reproduction - Organism inherits all of its genes from a single parent

13. Genetic variation - Different form of a gene results in different expression in the form of genetic makeup and outward appearance

14. Sexual Reproduction - Organism inherits all of its genes from two parents

15. Main Idea: Meiosis produces haploid gametes. Chapter 10 section 1 Meiosis

16. Human body cells have 46 chromosomes. 2. Each parent contributes 23 chromosomes, resulting in 23 pairs of chromosomes.

17. Sexual Reproduction and Genetics Chapter 10 10.1 Meiosis 3. The chromosomes that make up a pair, one chromosome from each parent, are called homologous chromosomes. 4. Homologous chromosomes in body cells have the same length and the same centromere position and theycarry genes that control the same inherited traits.

18. 5. In order to maintain the same chromosome number from generation to generation, an organism produces gametes, which are sex cells that have half the number of chromosomes.

19. from mother from father child too much! Meiosis • Reduces the genetic material by half • Why is this necessary? meiosis reduces genetic content

20. Sexual Reproduction and Genetics Chapter 10 10.1 Meiosis Haploid and Diploid Cells 6. In humans, each gamete contain 23 chromosomes.

21. ploidy - how many times each chromosome is present in a cell. • Diploid – 2 copies of each chromosome • Triploid – 3 copies of each chromosome • Haploid – half the number of each chromosome

22. 7. A cell with n chromosomes is called a haploid cell. 8. A cell that contains 2n chromosomes is called a diploid cell.

23. Sexual Reproduction and Genetics Chapter 10 10.1 Meiosis 9. Gametes are formed during a process called meiosis, which is a type of cell division that reduces the number of chromosomes; therefore, it is referred to as reduction division.

24. 10. Meiosis occurs in the reproductive structures of organisms that reproduce sexually.

25. 11. Meiosis reduces the chromosome number by half through the separation of homologous chromosomes.

26. 12. A cell with 2n number of chromosomes will have gametes with n number of chromosomes after meiosis. Fertilization- Process by which one Haploid gamete combines With another haploid gamete

27. 13. Meiosis involves two consecutive cell divisions called meiosis I and meiosis II.

28. 14. Mitosis consists of only one set of division phases and produces two identical diploid daughter cells. Meiosis consists of two sets of divisions and produces four haploid daughter cells that are not identical.

29. Meiosis is important because it results in genetic variation.

30. 16.Pair of homologous chromosomes line up at the equator during metaphase I. How the chromosomes line up is a random process that results in gametes with different combinations of chromosomes.

31. 17. Depending on how the chromosomes line up at the equator, four gametes with four different combinations of chromosomes can result.

32. 18. Genetic variation also is produced during crossing over and fertilization, when gametes randomly combine.

33. 19. During asexual reproduction, the organism inherits all of its chromosomes from a single parent. The new individual is genetically identical to its parent.

34. 10.2 Vocabulary Mendelian Genetics True breeding - plant consistently produces offspring with only one form of a trait Self fertilization - when a male gamete within a flower combines with a female gamete in the same flower Cross pollination - transferring a male gamete from the flower of one pea plant to the female reproductive organ in a flower of another pea plant

35. Genetics - Science of heredity P generation - Parent generation; true breeding; Cross between parents with different forms of a trait F1 generation - The offspring of the P cross are called the first filial (F1) generation; filius is Latin for son F2 generation - The offspring of the f1 generation

36. Allele - Alternative form that a single gene may have for a particular trait *Traits - Characteristics that are inherited Dominant - Mendel’s name for a specific trait that appeared in the F1 generation Recessive - Mendel’s name for a specific trait hidden or masked in the F1 generation

37. Homozygous - Organism with two of the same alleles for a specific trait; YY or yy Heterozygous - Organism with two different alleles for a specific trait; Yy Hybrid - Organism heterozygous for a specific trait; Yy

38. Genotype - An organism’s allele pairs; genetic makeup; the letters that represent the genes Phenotype - Observable characteristic that is expressed as a result of an allele pair; physical appearance Law of Segregation - Mendelian law stating that two alleles for each trait separate during meiosis

39. Monohybrid cross - A cross between hybrids for a single trait; Yy x Yy; Dihybrid cross - A cross between hybrids for 2 traits; YyRr Law of Independent Assortment - Mendelian law stating that a random distribution of alleles occurs during gamete formation; demonstrated in the dihybrid cross by the equal chance that each pair of alleles

40. *FOIL Method - used to determine gametes in a dihybrid; Punnett Squares - Used to predict the possible ratios of offspring of a cross between two known genotypes; keeps track of possible genotypes involved in a cross *Probability - likelihood that a particular event will occur; helps to predict the average outcome of a large number of events

41. 10.2 Mendelian Genetics Main Idea - Mendel explained how a dominant allele can mask (hide) the presence of a recessive allele.

42. Gregor Mendel • 1866 • Austrian monk • Plant breeder Mendel was the first person to succeed in predicting how traits are transferred from one generation to the next.

43. Sexual Reproduction and Genetics Chapter 10 10.2 Mendelian Genetics How Genetics Began • The passing of traits to the next generation is called inheritance, or heredity.

44. 2. Mendel chose to study pea plants. Contrasting characters- green & yellow wrinkled & round Reproduce sexually Crosses can be controlled Short life cycles Produce large number of offspring

45. In nature the pea plants are true (pure) breeding. True (pure) breeding means that the pea plant consistently produces offspring with only one form of a trait. Self-fertilization occurs when a male gamete within a flower combines with a female gamete in the same flower. Result: the plant will have characteristics only from 1 parent Short pea plant Tall pea plant

46. 5. Mendel performed cross pollination by transferring a male gamete from the flower of one pea plant to the female reproductive organ in a flower of another pea plant.

47. Section 10.1 Summary – pages 253-262 Mendel was a careful researcher He studied only one trait at a time to control variables, and he analyzed his data mathematically. The tall pea plants he worked with were from populations of plants that had been tall for many generations and had always produced tall offspring.

48. 6. Genetics is the scientific study of heredity.

49. Sexual Reproduction and Genetics Chapter 10 10.2 Mendelian Genetics 7. The parent generation is also known as the P generation. • Cross between parents with different forms of a trait

50. Sexual Reproduction and Genetics Chapter 10 10.2 Mendelian Genetics 8. The offspring of this P cross are called the first filial (F1) generation. Filius-latin for son