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  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10
  • Biology, 9th ed,Sylvia Mader Meiosis & Sexual Reproduction Slide # Chapter 10

10 Lecture Animation Ppt 10 Lecture Animation Ppt Presentation Transcript

  • egg FERTILIZATION MEIOSIS MITOSIS MITOSIS sperm n n 2n 2n 2n 2n zygote haploid (n) n = 23 2n = 46 diploid (2n) SPERMATOGENESIS OOGENESIS Metamorphosis and maturation Primary spermatocyte Primary oocyte zygote egg Secondary oocyte Meiosis II is completed after entry of sperm spermatids sperm Secondary spermatocytes First polar body Second polar body fusion of sperm nucleus and egg nucleus sperm nucleus 2n 2n 2n n n n n n n n n Meiosis I Meiosis II Meiosis I Fertilization cont'd Meiosis II Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  • Outline
    • Reduction in Chromosome Number
      • Homologous Pairs
      • Meiosis Overview
    • Genetic Variation
      • Crossing-Over
      • Independent Assortment
      • Fertilization
    • Phases of Meiosis
      • Meiosis I
      • Meiosis II
    • Meiosis Compared to Mitosis
    • Human Life Cycle
    • Changes in Chromosome Number and Structure
  • Meiosis: Halves the Chromosome Number
    • Special type of cell division
    • Used only for sexual reproduction
    • Halves the chromosome number prior to fertilization
      • Parents diploid
      • Meiosis produces haploid gametes
      • Gametes fuse in fertilization to form diploid zygote
      • Becomes the next diploid generation
  • Homologous Pairs of Chromosomes
    • In diploid body cells chromosomes occur in pairs
    • Humans have 23 different types of chromosomes
    • Diploid cells have two of each type
    • Chromosomes of the same type are said to be homologous
      • They have the same length
      • Their centromeres are positioned in the same place
      • One came from the father (the paternal homolog) the other from the mother (the maternal homolog)
      • When stained, they show similar banding patterns
      • A location on one homologue contains gene for the same trait that occurs at this locus on the other homologue
        • Although the genes may code for different variations of that trait
        • Alternate forms of a gene are called alleles
  • Homologous Chromosomes a. sister chromatids homologous pair chromosome chromosome Nonsister chromatids duplication duplication centromere kinetochore paternal chromosome maternal chromosome b. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  • Animation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
  • Homologous Pairs of Chromosomes
    • Homologous chromosomes have genes controlling the same trait at the same position
      • Each gene occurs in duplicate
      • A maternal copy from the mother
      • A paternal copy from the father
    • Many genes exist in several variant forms in a large population
    • Homologous copies of a gene may encode identical or differing genetic information
    • The variants that exist for a gene are called alleles
    • An individual may have:
      • Identical alleles for a specific gene on both homologs (homozygous for the trait), or
      • A maternal allele that differs from the corresponding paternal allele (heterozygous for the trait)
  • Overview of Meiosis n = 2 n = 2 2n = 4 2n = 4 MEIOSIS I Homologous pairs synapse and then separate. centrioles sister chromatids synapsis nucleolus centromere chromosome duplication MEIOSIS II Sister chromatids separate, becoming daughter chromosomes. Four haploid daughter cells Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  • Animation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
  • Phases of Meiosis I: Prophase I & Metaphase I
    • Meiosis I (reductional division):
      • Prophase I
        • Each chromosome internally duplicated (consists of two identical sister chromatids)
        • Homologous chromosomes pair up – synapsis
        • Physically align themselves against each other end to end
        • End view would show four chromatids – Tetrad
      • Metaphase I
        • Homologous pairs arranged onto the metaphase plate
  • Phases of Meiosis I: Anaphase I & Telophase I
      • Anaphase I
        • Synapsis breaks up
        • Homologous chromosomes separate from one another
        • Homologues move towards opposite poles
        • Each is still an internally duplicate chromosome with two chromatids
      • Telophase I
        • Daughter cells have one internally duplicate chromosome from each homologous pair
        • One (internally duplicate) chromosome of each type (1n, haploid)
  • Phases of Meiosis I: Cytokinesis I & Interkinesis
      • Cytokinesis I
        • Two daughter cells
        • Both with one internally duplicate chromosome of each type
        • Haploid
        • Meiosis I is reductional (halves chromosome number)
    • Interkinesis
      • Similar to mitotic interphase
      • Usually shorter
      • No replication of DNA
  • Animation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
  • Genetic Variation: Crossing Over
    • Meiosis brings about genetic variation in two key ways:
      • Crossing-over between homologous chromosomes, and
      • Independent assortment of homologous chromosomes
    • Crossing Over:
      • Exchange of genetic material between nonsister chromatids during meiosis I
      • At synapsis, a nucleoprotein lattice (called the synaptonemal complex) appears between homologues
        • Holds homologues together
        • Aligns DNA of nonsister chromatids
        • Allows crossing-over to occur
      • Then homologues separate and are distributed to different daughter cells
  • Crossing Over A B b B C c C D D D A A a b B b c C c d d d a a nucleoprotein lattice sister chromatids of a chromosome sister chromatids of its homologue chiasmata of nonsister nhromatids 1 and 3 Bivalent forms b. 1 2 3 4 1 2 3 4 1 2 3 4 a. c. d. Crossing-over has occurred Daughter chromosomes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Courtesy Dr. D. Von Wettstein
  • Animation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
  • Genetic Variation: Independent Assortment
    • Independent assortment:
      • When homologues align at the metaphase plate:
        • They separate in a random manner
        • The maternal or paternal homologue may be oriented toward either pole of mother cell
      • Causes random mixing of blocks of alleles into gametes
  • Animation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
  • Independent Assortment Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  • Recombination Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © American Images, Inc/Getty Images
  • Genetic Variation: Fertilization
    • When gametes fuse at fertilization:
      • Chromosomes donated by the parents are combined
      • In humans, (2 23 ) 2 = 70,368,744,000,000 chromosomally different zygotes are possible
    • If crossing-over occurs only once
      • (4 23 ) 2 , or 4,951,760,200,000,000,000,000,000,000 genetically different zygotes are possible
  • Genetic Variation: Significance
    • Asexual reproduction produces genetically identical clones
    • Sexual reproduction cause novel genetic recombinations
    • Asexual reproduction is advantageous when environment is stable
    • However, if environment changes, genetic variability introduced by sexual reproduction may be advantageous
      • Offspring adapt to that environment
  • Phases of Meiosis II: Similar to Mitosis
    • Metaphase II
      • Overview
        • Unremarkable
        • Virtually indistinguishable from mitosis of two haploid cells
      • Prophase II – Chromosomes condense
      • Metaphase II – Chromosomes align at metaphase plate
      • Anaphase II
        • Centromere dissolves
        • Sister chromatids separate and become daughter chromosomes
      • Telophase II and cytokinesis II
        • Four haploid cells
        • All genetically unique
  • Animation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
  • Meiosis I & II in Plant Cells (Cont.) Prophase I Chromosomes have duplicated. Homologous chromosomes pair during synapsis and crossing-over occurs. Metaphase I Homologous pairs align Independently at the metaphase plate. Anaphase I Homologous chromosomes separate and move toward the poles. Prophase II Cells have one chromosome from each homologous pair. Metaphase II Chromosomes align at the metaphase plate. Anaphase II Sister chromatids separate and become daughter chromosomes. kinetochore MEIOSIS I MEIOSIS II Animal Cell at Interphase centrosome has centrioles Plant Cell at Interphase 2n = 4 n = 2 n = 2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Ed Reschke
  • Meiosis I & II in Plant Cells Telophase I Daughter cells have one chromosome from each homologous pair. Interkinesis Chromosomes still consist of two chromatids. Telophase II Spindle disappears, nuclei form, and cytokinesis takes place. Daughter cells Meiosis results in four haploid daughter cells. MEIOSIS I cont'd MEIOSIS II cont'd n = 2 n = 2 n = 2 n = 2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Ed Reschke
  • Animation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
  • Meiosis vs. Mitosis
    • Meiosis
      • Requires two nuclear divisions
      • Chromosomes synapse and cross over
      • Centromeres survive Anaphase I
      • Halves chromosome number
      • Produces four daughter nuclei
      • Produces daughter cells genetically different from parent and each other
      • Used only for sexual reproduction
    • Mitosis
      • Requires one nuclear division
      • Chromosomes do not synapse nor cross over
      • Centromeres dissolve in mitotic anaphase
      • Preserves chromosome number
      • Produces two daughter nuclei
      • Produces daughter cells genetically identical to parent and to each other
      • Used for asexual reproduction and growth
  • Meiosis Compared to Mitosis Prophase I Synapsis and crossing-over occur. Metaphase I Homologous pairs align independently at the metaphase plate. Anaphase I Homologous chromosomes separate and move towards the poles. Prophase Metaphase Chromosomes align at the metaphase plate. Anaphase Sister chromatids separate and become daughter chromosomes. MEIOSIS I MITOSIS 2n = 4 2n = 4 Telophase I Daughter cells are forming and will go on to divide again. Telophase Daughter cells are forming. Sister chromatids separate and become daughter chromosomes. Two diploid daughter cells. Their nuclei are genetically identical to the parent cell. Four haploid daughter cells. Their nuclei are genetically different from the parent cell. MEIOSIS I cont'd MEIOSIS II MITOSIS cont'd Daughter cells Daughter cells n = 2 n = 2 n = 2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  • Animation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
  • Meiosis I Compared to Mitosis
  • Meiosis II Compared to Mitosis
  • Life Cycle Basics: Plants
    • Haploid multicellular “individuals” alternate with diploid multicellular “individuals”
    • The haploid individual:
      • Known as the gametophyte
      • May be larger or smaller than the diploid individual
    • The diploid individual:
      • Known as the sporophyte
      • May be larger or smaller than the haploid individual
    • Mosses are haploid most of their life cycle
    • Ferns & higher plants have mostly diploid life cycles
    • In fungi and most algae, only the zygote is diploid
    • In plants gametes are produced by haploid individuals
      • Plants have both haploid and diploid phases in their life cycle
  • Life Cycle Basics: Animals
    • In familiar animals:
      • “ Individuals” are diploid; produce haploid gametes
      • Only haploid part of life cycle is the gametes
      • The products of meiosis are always gametes
      • Meiosis occurs only during gametogenesis
        • Production of sperm
          • Spermatogenesis
          • All four cells become sperm
        • Production of eggs
          • Oogenesis
          • Only one of four nuclei get cytoplasm
            • Becomes the egg or ovum
            • Others wither away as polar bodies
  • The Human Life Cycle
    • Sperm and egg are produced by meiosis
    • A sperm and egg fuse at fertilization
    • Results in a zygote
      • The one-celled stage of an individual of the next generation
      • Undergoes mitosis
    • Results in multicellular embryo that gradually takes on features determined when zygote was formed
    • All growth occurs as mitotic division
    • As a result of mitosis, each somatic cell in body
      • Has same number of chromosomes as zygote
      • Has genetic makeup determined when zygote was formed
  • The Human Life Cycle egg FERTILIZATION MEIOSIS MITOSIS MITOSIS sperm n n 2n 2n 2n 2n zygote haploid (n) n = 23 2n = 46 diploid (2n) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  • Gametogenesis in Mammals Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. SPERMATOGENESIS OOGENESIS Metamorphosis and maturation Primary spermatocyte Primary oocyte zygote egg Secondary oocyte Meiosis II is completed after entry of sperm spermatids sperm Secondary spermatocytes First polar body Second polar body fusion of sperm nucleus and egg nucleus sperm nucleus 2n 2n 2n n n n n n n n n Meiosis I Meiosis II Meiosis I Fertilization cont'd Meiosis II
  • Changes in Chromosome Number
    • Euploid is the correct number of chromosomes in a species.
    • Aneuploid is change in the chromosome number
      • Results from nondisjunction
        • Monosomy - only one of a particular type of chromosome,
        • Trisomy - three of a particular type of chromosome
  • Changes in Chromosome a. b. pair of homologous chromosomes 2n 2n 2n + 1 2n + 1 2n + 1 2n - 1 normal normal pair of homologous chromosomes Meiosis I Meiosis II Fertilization Zygote nondisjunction nondisjunction Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2n - 1 2n - 1
  • Trisomy
    • Trisome 21
      • Occurs when an individual has three of a particular type of chromosome
      • The most common autosomal trisomy seen among humans
      • Also called Down syndrome
      • Recognized by these characteristics:
        • short stature
        • eyelid fold
        • flat face
        • stubby finger
        • wide gap between first and second toes
  • Trisomy 21 a. b. extra chromosome 21 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a: © Jose Carrilo/PhotoEdit; b: © CNRI/SPL/Photo Researchers
  • Changes in Sex Chromosome
    • Result from inheriting too many or too few X or Y chromosomes
    • Nondisjunction during oogenesis or spermatogenesis
      • Turner syndrome (XO)
        • Female with single X chromosome
        • Short, with broad chest and widely spaced nipples
        • Can be of normal intelligence and function with hormone therapy
      • Klinefelter syndrome (XXY) – a male
        • Male with underdeveloped testes and prostate; some breast overdevelopment
        • Long arms and legs; large hands
        • Near normal intelligence unless XXXY, XXXXY, etc.
        • No matter how many X chromosomes, presence of Y renders individual male
  • Changes in Sex Chromosome a. Turner syndrome b. Klinefelter syndrome Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a: Courtesy UNC Medical Illustration and Photography; b: Courtesy Stefan D. Schwarz, http://klinefeltersyndrome.org
  • Changes in Chromosome Structure
    • Changes in chromosome structure include:
      • Deletions
        • One or both ends of a chromosome breaks off
        • Two simultaneous breaks lead to loss of an internal segment
      • Duplications
        • Presence of a chromosomal segment more than once in the same chromosome
      • Translocations
        • A segment from one chromosome moves to a non-homologous chromosome
        • Follows breakage of two nonhomologous chromosomes and improper re-assembly
  • Animation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
  • Changes in Chromosome Structure
    • Duplication
      • A segment of a chromosome is repeated in the same chromosome
    • Inversion
      • Occurs as a result of two breaks in a chromosome
        • The internal segment is reversed before re-insertion
        • Genes occur in reverse order in inverted segment
  • Animation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
  • Types of Chromosomal Mutation c. Inversion d. Translocation b. Duplication a. Deletion + a b c d e f g a b c d e f g h a b c d e f g a b e f g l m n o p q r a b c d e f l m n o p a b c d e f g a b c d e f g b c d e f g g h q r d e a c d Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  • Animation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
  • Animation Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
  • Types of Chromosomal Mutation deletion lost a. b. + h a b c d e f g h a b c d e f g Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. b: Courtesy The Williams Syndrome Association
  • Types of Chromosomal Mutation translocation a. b. a b c d e f g h s t u v w x y z a b c d e f g h s t u v w x y z Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. b: American Journal of Human Genetics by N. B. Spinner. Copyright 1994 by Elsevier Science & Technology Journals. Reproduced with permission of Elsevier Science & Technology Journals in the format Textbook via Copyright Clearance Center
  • Review
    • Reduction in Chromosome Number
      • Meiosis Overview
      • Homologous Pairs
    • Genetic Variation
      • Crossing-Over
      • Independent Assortment
      • Fertilization
    • Phases of Meiosis
      • Meiosis I
      • Meiosis II
    • Meiosis Compared to Mitosis
    • Human Life Cycle
    • Changes in Chromosome Number and Structure
  • egg FERTILIZATION MEIOSIS MITOSIS MITOSIS sperm n n 2n 2n 2n 2n zygote haploid (n) n = 23 2n = 46 diploid (2n) SPERMATOGENESIS OOGENESIS Metamorphosis and maturation Primary spermatocyte Primary oocyte zygote egg Secondary oocyte Meiosis II is completed after entry of sperm spermatids sperm Secondary spermatocytes First polar body Second polar body fusion of sperm nucleus and egg nucleus sperm nucleus 2n 2n 2n n n n n n n n n Meiosis I Meiosis II Meiosis I Fertilization cont'd Meiosis II Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.