1. Chapter 10

2.  The instructions for all your traits are located on your DNA on small segments called genes. Genes are located on chromosomes Every species has a unique chromosome number

3. Bat 94squirrel 40 chicken 78 House fly 12mosquito 6 king crab 208 Apple 34carp 104 potato 48 Crab eating rat 92 (highest no. for mammals) Adders tongue –fern – 1260 (highest) Jack jumper ant – 2 (lowest number) Humans - 46

5. Sexual Reproduction and Genetics Chapter 10 Our species has 46 chromosomes Each parent contributes half of its chromosomes 23 from dad, 23 from mom

6. Sexual Reproduction and Genetics  Same length  Same centromere position  Carry genes that control the same inherited traits Chapter 10  Homologous chromosomes—one of two paired chromosomes, one from each parent Chromosome come in pairs

7. Haploid and Diploid Cells  Human gametes contain 23 chromosomes. Sexual Reproduction and Genetics  A cell (sex cells) with n chromosomes is called a haploid cell.  A cell (body cells) that contains 2n chromosomes is called a diploid cell. An organism produces gametes (sex Cells) to maintain the same number of chromosomes from generation to generation. Chapter 10

8.  The sexual life cycle in animals involves meiosis. Sexual Reproduction and Genetics  Meiosis produces gametes.  When gametes combine in fertilization, the number of chromosomes is restored. Chapter 10

9.  What process produces gametes?

10. Meiosis  Reduces the chromosome number by half through the separation of homologous chromosomes Sexual Reproduction and Genetics  Involves two consecutive cell divisions called meiosis I and meiosis II 10.1 Meiosis Chapter 10

11. Sexual Reproduction and Genetics  Interphase  Chromosomes replicate.  Chromatin condenses. Chapter 10 Interphase

12. Sexual Reproduction and Genetics 10.1 Meiosis  Prophase I  Pairing of homologous chromosomes  nuclear envelope breaks down.  Spindles form. Chapter 10 Prophase I Meiosis I

13. Sexual Reproduction and Genetics 10.1 Meiosis  Prophase I  Crossing over produces exchange of genetic information.  chromosomal segments are exchanged between a pair of homologous chromosomes. Chapter 10

14. Sexual Reproduction and Genetics 10.1 Meiosis  Metaphase I  Homologous chromosomes line up at the equator. Chapter 10 Metaphase I

15. Sexual Reproduction and Genetics 10.1 Meiosis  Anaphase I Chapter 10 Anaphase I  Homologous chromosomes separate and move to opposite poles of the cell.

16. Sexual Reproduction and Genetics 10.1 Meiosis  Telophase I  spindles break down.  Chromosomes uncoil and form two nuclei.  The cell divides. Chapter 10 Telophase I

17.  Prophase II Sexual Reproduction and Genetics 10.1 Meiosis Chapter 10 spindle apparatus forms and the chromosomes condense. Prophase II

18.  Metaphase II Sexual Reproduction and Genetics 10.1 Meiosis Chapter 10  A haploid number of chromosomes line up at the equator. Metaphase II

19. Sexual Reproduction and Genetics 10.1 Meiosis  Anaphase II Chapter 10 Anaphase II  The sister chromatids are pulled apart move toward the opposite poles of the cell.

20. Sexual Reproduction and Genetics 10.1 Meiosis Chapter 10  Telophase II the nuclear membrane and nuclei reform. Telophase II

21. Meiosis II Sexual Reproduction and Genetics  Cytokinesis results in four haploid cells, each with n number of chromosomes. 10.1 Meiosis Chapter 10 Cytokinesis

22. Meiosis overview

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

24.  1800s  Austrian monk  Cross bred pea plants Why did he choose pea plants? Collected data over many generations

25.  Mendel studied seven different traits. Sexual Reproduction and Genetics  Seed or pea color  Flower color  Seed pod color  Seed shape or texture  Seed pod shape  Stem length  Flower position 10.2 Mendelian Genetics Chapter 10

26.  The parent generation is also known as the P generation. Sexual Reproduction and Genetics 10.2 Mendelian Genetics Chapter 10

27. Sexual Reproduction and Genetics  The second filial (F 2 ) generation is the offspring from the F 1 cross. 10.2 Mendelian Genetics Chapter 10  The offspring of this P cross are called the first filial (F 1 ) generation.

28. Mendel concluded that there must be 2 forms of the seed traits in the pea plants Sexual Reproduction and Genetics  Allele  An alternative form of a single gene passed from generation to generation 10.2 Mendelian Genetics Chapter 10

29.  Dominant- trait that is expressed in the F1 generation  Recessive- trait that is masked in the F2 generation  He also concluded that the 3:1 ratio observed during his experiments could be explained if alleles were paired in each of the plants

30. Dominance Sexual Reproduction and Genetics  An organism with two of the same alleles for a particular trait is homozygous  Written as BB or bb  An organism with two different alleles for a particular trait is heterozygous  Written as Bb 10.2 Mendelian Genetics Chapter 10

31. Genotype and Phenotype Sexual Reproduction and Genetics  An organism’s allele pairs are called its genotype.  The observable characteristic or outward expression of an allele pair is called the phenotype. 10.2 Mendelian Genetics Chapter 10

32. Monohybrid Cross Sexual Reproduction and Genetics  A cross that involves hybrids for a single trait is called a monohybrid cross. 10.2 Mendelian Genetics Chapter 10

33. Sexual Reproduction and Genetics Punnett Squares  Predict the possible offspring of a cross between two known genotypes 10.2 Mendelian Genetics Punnett Squares Chapter 10

35.  Law of segregation – two alleles for each pair separate during meiosis

36. Sexual Reproduction and Genetics Law of Independent Assortment 10.2 Mendelian Genetics Chapter 10  Random distribution of alleles occurs during gamete formation  Genes on separate chromosomes sort independently during meiosis.  Each allele combination is equally likely to occur.

37. Sexual Reproduction and Genetics Punnett Square— Dihybrid Cross  Cross involving 2 traits  Four types of alleles from the male gametes and four types of alleles from the female gametes can be produced.  The resulting phenotypic ratio is 9:3:3:1. Chapter 10

38. Sexual Reproduction and Genetics Dihybrid Cross  The simultaneous inheritance of two or more traits in the same plant is a dihybrid cross.  Dihybrids are heterozygous for both traits. 10.2 Mendelian Genetics Chapter 10

40. Have you ever had some say they saw your “twin” or have you seen someone that looked just like you? Is this ever possible if they are not related to you???

41. Genetic Recombination  The new combination of genes produced by crossing over and independent assortment 10.3 Gene Linkage and Polyploidy Sexual Reproduction and Genetics  Combinations of genes due to independent assortment can be calculated using the formula 2 n, where n is the number of chromosome pairs.  For us that would be 2 23 times 2 23 (after fertilization) or over 70 trillion possible combinations!! Chapter 10

42. Gene Linkage  The linkage of genes on a chromosome results in an exception to Mendel’s law of independent assortment because linked genes usually do not segregate independently. Sexual Reproduction and Genetics 10.3 Gene Linkage and Polyploidy Chapter 10

43. Polyploidy Sexual Reproduction and Genetics  Polyploidy is the occurrence of one or more extra sets of all chromosomes in an organism.  A triploid organism, for instance, would be designated 3n, which means that it has three complete sets of chromosomes. 10.3 Gene Linkage and Polyploidy Chapter 10