General Biology 1004 Chapter 8 Lecture Handout, Summer 2005 Dr. Frisby

Transcription

1 Slide 1 CHAPTER 8 The Cellular Basis of Reproduction and Inheritance PowerPoint Lecture Slides for Essential Biology, Second Edition & Essential Biology with Physiology Presentation prepared by Chris C. Romero Copyright 2004 Pearson Education, Inc. publishing as Benjamin Cummings Neil Campbell, Jane Reece, and Eric Simon Slide 2 BIOLOGY AND SOCIETY: A $50,000 EGG! A few years ago a sterile couple was willing to pay $50,000 to a woman willing to donate her eggs Slide 3 Infertility Affects one in ten American couples In vitro fertilization (IVF) A sperm and an egg are joined in a petri dish The embryo is implanted into the mother s uterus IVF is one of many reproductive technologies Figure 8.1

2 Slide 4 WHAT CELL REPRODUCTION ACCOMPLISHES Reproduction Slide 5 Cell reproduction or Cell division plays a role in Slide 6 Passing On the Genes from Cell to Cell Before a parent cell divides, it duplicates its The two resulting daughter cells are genetically identical

3 Slide 7 The Reproduction of Organisms In asexual reproduction, single-celled organisms reproduce by simple cell division (a) Amoeba Figure 8.2a Slide 8 Some multicellular organisms can divide into pieces that then grow into new individuals (b) Sea star Figure 8.2b Slide 9 Sexual reproduction is different It requires fertilization of an egg by a sperm Production of egg and sperm is called meiosis

4 Slide 10 THE CELL CYCLE AND MITOSIS A genome Slide 11 Eukaryotic Chromosomes Chromosomes Figure 8.3 Slide 12 The DNA in a cell is packed into an elaborate, multilevel system of coiling and folding Chromatin DNA double helix Histones Beads on a string Nucleosome Tight helical fiber Supercoil Sister chromatids Centromere Figure 8.4

5 Slide 13 Before a cell divides, it duplicates all of its, resulting in two copies called sister chromatids Slide 14 When the cell divides, the sister chromatids separate from each other Chromosome duplication Sister chromatids Chromosome distribution to daughter cells Figure 8.5 Slide 15 The Cell Cycle Eukaryotic cells that divide undergo an orderly sequence of events called the cell cycle

6 Slide 16 The cell cycle consists of two distinct phases S phase (DNA synthesis; chromosome duplication) Interphase (90% of time) G 1 G 2 Mitotic phase (M) (10% of time) Cytokinesis Mitosis Figure 8.6 Slide 17 Mitosis and Cytokinesis Interphase Mitosis Centrosomes (w ith centriole paris) Chromatin Nucleolus Nuclear envelope Plasma membrane Figure Slide 18 Mitosis consists of four distinct phases

7 Slide 19 Prophase Metaphase Early Centrosome mitotic spindle Centromere Fragments of nuclear envelope Chromosome, consisting of two sister chromatids Spindle microtubules Spindle Figure Slide 20 Anaphase Telophaseand Cytokinesis Telophase Anaphase Nucleolus forming Cleavage furrow Daughter Nuclear envelope forming Figure Slide 21 Cytokinesis

8 Slide 22 Cytokinesis is different in plant and animal cells Cleavage furrow Cleavage furrow Contracting ring of Microfilaments (actin) (a) Animal cell cytokinesis Daughter cells Figure 8.8a Slide 23 Wall of parent cell Cell plate forming Daughter nucleus Vesicles containing New cell wall cell wall material Cell wall Cell plate (b) Plant cell cytokinesis Daughter cells Figure 8.8b Slide 24 Cancer Cells: Growing Out of Control Normal plant and animal cells have a cell cycle control system When the cell cycle control system malfunctions

9 Slide 25 What is cancer? What Is Cancer? Slide 26 Cancer cells divide excessively Cancer cells spread from a malignant tumor Metastasis is the spread of cancer Lymph vessels Tumor Glandular tissue A tumor grows from a single cancer cell. Cancer cells invade neighboring tissue. Metastasis Cancer cells spread through lymph and blood vessels to other parts of the body Figure 8.9 Slide 27 Cancer treatment Cancer Treatment

10 Slide 28 Cancer cells are often grown in culture for study Figure 8.10 Slide 29 Cancer Prevention and Survival Cancer prevention includes changes in lifestyle Not smoking Avoiding exposure to the sun Eating a high -fiber, low-fat diet Visiting the doctor regularly Performing regular self -examinations Slide 30 MEIOSIS, THE BASIS OF SEXUAL REPRODUCTION Sexual reproduction depends on Figure 8.11

11 Slide 31 Homologous Chromosomes Different organisms of the same species have the same number and types of Slide 32 A somatic cell Slide 33 A karyotype is a micrograph of an orderly arrangement of Homologous are matching pairs of Pair of homologous Centromere Sister chromatids Figure 8.12

12 Slide 34 Humans have Slide 35 Gametes and the Life Cycle of a Sexual Organism Haploid gametes (n = 23) The life cycle of a multicellular organism is the sequence of stages leading from the adults of one generation to the adults of the next Meiosis Egg cell Sperm cell Fertilization Diploid zygote (2n = 46) Multicellular diploid adults (2n = 46) Mitosis and development Figure 8.13 Slide 36 Humans are diploid organisms

13 Slide 37 Fertilization Slide 38 Sexual life cycles involve an alternation of diploid and haploid stages 1 Chromosomes 2 duplicate Homologous separate 3 Sister chromatids separate Homologous pair of in diploid parent cell Homologous pair of duplicated Sister chromatids Interphase before meiosis Meiosis I Meiosis II Figure 8.14 Slide 39 In meiosis The Process of Meiosis Haploid gametes are produced in diploid organisms Two consecutive divisions occur, meiosis I and meiosis II, preceded by interphase Crossing over occurs Centrosomes (with centriole pairs) Nuclear envelope Interphase Chromatin Chromosomes duplicate Figure

14 Slide 40 Meiosis I: Homologous separate Prophase I Meiosis I Sites of crossing over Spindle Metaphase I Microtubules attached to Chromosomes Anaphase I Sister chromatids remain attached Telophase I and Cytokinesis Cleavage furrow Sister chromatids Tetrad Centromere Homologous pair and exchange segments Tetrads line up Pairs of homologous split up Two haploid cells form: are still double Figure Slide 41 Meiosis II Meiosis II: Sister chromatids separate Prophase II Metaphase II Anaphase II TelophaseII and Cytokinesis Sister chromatids separate Haploid daughter cells forming During another round of cell division, the sister chromatids finally separate; four haploid daughter cells result, containing single chromosome s Figure Slide 42 Review: Comparing Mitosis and Meiosis Mitosis Meiosis Parent cel l (before chromosome duplication) Duplicated chromosome (two sister chromatids ) Prophase Sit e of crossing over Meiosis I Chromosome Chromosome duplication dupl ication Tetrad formed by pairing of homologous Pairing of homologous 2n = 4 Prophase I Metaphase Chromosomes Tetrads al ign at the al ign at t he middle of middle of the cell the cell Metaphase I Anaphase Telophase Si ster chromatids separate 2n during anaphase 2n Daughter cells of mitosis Homologous Anaphase I Telophase I separate during anaphase I; si ster Haploid chromatids Daughter remain n = 2 cells of together meiosis I No further chromosomal dupl ication; sister chromatids Meiosis II separate during anaphase I I n n n n Daughter cells of meiosis II Figure 8.16

15 Slide 43 The Origins of Genetic Variation Offspring of sexual reproduction are genetically different from their parents and from one another Slide 44 Independent Assortment of Chromosomes In independent assortment every chromosome pair orients independently of the others during meiosis Possibility 1 Possibility 2 Metaphase of meiosis I Metaphase of meiosis II Gametes Combination a Combination b Combination c Combination d Figure 8.17 Slide 45 Random Fertilization The human egg cell is fertilized randomly by one sperm, leading to genetic variety in the zygote

16 Slide 46 Crossing Over Tetrad In crossing over Prophase I of meiosis Metaphase I Chiasma, site of crossing over Spindle microtubules Metaphase II Gametes Recombinant Figure 8.18 Slide 47 When Meiosis Goes Awry What happens when errors occur in meiosis? Slide 48 Down Syndrome: An Extra Chromosome 21 Down Syndrome Figure 8.19

17 Slide 49 The incidence of Down Syndrome increases with the age of the mother Figure 8.20 Slide 50 How Accidents During Meiosis Can Alter Chromosome Number In nondisjunction Slide 51 Meiosis I Nondisjunction Meiosis II Nondisjunction Gametes n + 1 n + 1 n - 1 n - 1 n + 1 n - 1 n n Number of (a) Nondisjunctionin meiosis I (b) Nondisjunctionin meiosis II Figure 8.21

18 Slide 52 The result of nondisjunction Egg cell n + 1 Sperm cell n (normal) Zygote 2n + 1 Figure 8.22 Slide 53 Abnormal Numbers of Sex Chromosomes Nondisjunction Also affects the sex Table 8.1 Slide 54 Breast development Poor beard growth Web of skin Two kinds of sex chromosome abnormalities Underdeveloped testes Constriction of aorta Poor breast develop ment Underdeveloped ovaries (a) A man with Klinefelter syndrome (XXY) (b) A woman with Turner syndrome (XO) Figure 8.23

19 Slide 55 EVOLUTION CONNECTION: NEW SPECIES FROM ERRORS IN CELL DIVISION Errors in meiosis may have been instrumental in the evolution of many species Slide 56 Polyploids Are new species Have more than two sets of homologous in each somatic cell Figure 8.24

20 Chapter 8 Study Objectives 1. Describe the process of invitro fertilization (IVF). Explain why some infertile couples need donate eggs to reproduce. Describe some of the ethical issues raised by this situation. 2. Describe the roles of cell division in living organisms. 3. Compare the genetic information in the of typical daughter cells. 4. Compare the cellular processes and cellular products of asexual and sexual reproduction. 5. Describe the basic structure of a chromosome, and explain how are duplicated. 6. Describe the key events of each phrase of the cell cycle. 7. Describe the key events of each phase of mitosis. 8. Compare the processes of cytokinesis in animal and plant cells. 9. Describe how the cell cycle control system normally functions and explain the consequences of errors in this system. 10. Explain how cancer cells are different from normal cells of the body. 11. Explain how you can reduce your risks of developing cancer. 12. Distinguish between the following pairs of terms: sex versus autosomes, somatic cells versus gametes, and diploid versus haploid cells. 13. Compare the processes and products of meiosis I and meiosis II. 14. Compare the overall processes and products of meiosis and mitosis. 15. Explain how independent assortment of during meiosis, random fertilization, and crossing over contribute to genetic diversity in offspring. 16. Explain the consequences of nondisjunction of autosomes or sex. 17. Explain how polyploidy species can evolve.