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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece.

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Presentation on theme: "Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece."— Presentation transcript:

1 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Chapter 13 Meiosis and Sexual Life Cycles

2 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Asexual vs. Sexual Reproduction Asexual reproduction – One parent  one genetically identical offspring Figure 13.2 Parent Bud 0.5 mm

3 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Asexual vs. Sexual Reproduction Sexual reproduction – Two parents  one unique offspring Figure 13.1

4 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 13.1: Genome Chromosomes DNA molecule and proteins (Chromatin) Genes

5 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings MEIOSIS Somatic (body) cells – Chromosomes are matched in homologous pairs Ex: human cells have 46 chromosomes = 23 pairs of homologous chromosomes

6 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings – Every chromosome has a match! = homologous pair Figure 8.12

7 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings – Every chromosome has a match! = homologous pair Figure 8.12 Why do we have 2 of each chromosome?

8 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Somatic Cells vs. Gametes – Somatic Cells 2 sets of chromosomes = Diploid (2n) (n = number of chromosomes in a single set)

9 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Somatic Cells vs. Gametes – Somatic Cells 2 sets of chromosomes = Diploid (2n) (n = number of chromosomes in a single set) – Gametes (eggs and sperm) 1 set of chromosomes = Haploid (n)

10 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Somatic cells = diploid cell An organism’s diploid cell has two sets of each of each chromosome 20 from Mom; 20 from Dad What is the diploid number of chromosomes in each of this organism’s somatic cells?

11 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Somatic cells = diploid cell An organism’s diploid cell has two sets of each of each chromosome 20 from Mom; 20 from Dad What is the diploid number of chromosomes in each of this organism’s somatic cells? 2n = 40

12 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings CHROMOSOME NUMBER AND STRUCTURE 8.19 A karyotype ordered arrangement of a cell’s chromosomes

13 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Human Kayotype- 22 pairs of autosomes, 1 pair sex chromosomes

14 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings chromosomes condensed A B C D -Sister chromatids -Nonsister chromatids -Homologous pair -Centromere

15 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Somatic cells vs. Gametes Diploid vs. Haploid 2n vs. n

16 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Somatic cells vs. Gametes Diploid vs. Haploid 2n vs. n How, when, where and why are haploid cells generated?

17 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 8.13 How are haploid gametes produced? = MEIOSIS!

18 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Overview of Meiosis- 2 cell divisions Diploid cell 2 Haploid cells 4 Haploid cells Separate homologues Separate sister chromatids Diploid cell

19 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Overview of Meiosis- 2 cell divisions Diploid 2n 2 Haploid 1n 4 Haploid 1n Separate homologues Separate sister chromatids (n = Chromosome #) Diploid 2n

20 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Interphase and meiosis I Interphase 

21 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Interphase and Meiosis I Interphase  Prophase I 1. Synapsis  Homolouges pair = Tetrads 2. Non-sisters cross over = Chiasmata

22 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Meiosis I Metaphase I  -Tetrads line up at center of cell

23 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Meiosis I Metaphase I  Anaphase I  -Homologous chromosomes separate

24 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Meiosis I Metaphase I  Anaphase I  Telophase I

25 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Review: Interphase and meiosis I Interphase  prophase I  metaphase I  anaphase I  telophaseI Figure 13.8

26 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Telophase I and cytokinesis  Prophase II -Spindles form in each cell

27 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Meiosis II Metaphase II  - Sister chromatids line up in center of cell

28 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Meiosis II Metaphase II  Anaphase II - Sister chromatids separate

29 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Meiosis II Metaphase II  Anaphase II  Telophase II - 4 Haploid cells

30 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Telophase I, cytokinesis, and meiosis II

31 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Overview of Meiosis Diploid 2n 2 Haploid 1n 4 Haploid 1n Separate homologues Separate sister chromatids n = Chromosome # Diploid 2n

32 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Meiosis vs. Mitosis 3 events distinguish Meiosis from Mitosis:

33 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Meiosis vs. Mitosis #1. Meiosis = Homologous chromosomes pair and exchange genetic information - Tetrads - Synapsis - Crossing over (chiasmata)

34 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Meiosis vs. Mitosis #2 Meiosis= Paired homologous chromosomes (tetrads) are positioned on the metaphase plate

35 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Meiosis vs. Mitosis #3 Anaphase I of Meiosis = homologous pairs move toward opposite poles of the cell

36 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Meiosis vs. Mitosis #3 Anaphase I of meiosis = homologous pairs move toward opposite poles of the cell Anaphase II of meiosis = sister chromatids separate

37 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 8.15 Review: A comparison of mitosis and meiosis Homologues pair Homologues split Sister Chromatids split Homologues do not pair

38 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 13.4: How does Meiosis produce Genetic Variation?

39 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 13.4: How does Meiosis produce Genetic variation? = Behavior of chromosomes during meiosis: 1.Crossing over 2.Independent assortment = Fertilization: 3. Random fertilization

40 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 1. Crossing Over - Produces recombinant chromosomes

41 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 2. Independent Assortment of Chromosomes Homologous orient randomly at metaphase I of meiosis

42 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 2. Independent Assortment of Chromosomes Homologous orient randomly at metaphase I of meiosis

43 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 3. Random Fertilization The fusion of gametes – Can produce a zygote with about 64 trillion diploid combinations!!!

44 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ch. 13 Asexual vs. Sexual reproduction Homologous Chromosomes Somatic cells= Diploid (2n) Gametes= Haploid (1n)

45 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Review! Ch. 13: Meiosis Diploid cell  4 Haploid cells (gametes) Major events? – Prophase I, Anaphase I, Anaphase II Meiosis vs. Mitosis? How does Meiosis produce variation?


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