BIOLOGY COLLEGE PHYSICS Chapter 11 MEIOSIS AND SEXUAL REPRODUCTION Chapter # Chapter Title PowerPoint Image Slideshow
CAMPBELL BIOLOGY TENTH EDITION Reece Urry Cain Wasserman Minorsky Jackson 13 Meiosis and Sexual Life Cycles 2014 Pearson Education, Inc.
Semen attack unsuspecting ovum
Figure 13.1
Asexual Repro - Clones
Aspen tree = cloned
Figure 13.3b Karyotype Homologous chromosomes 46 or 23 prs autosomes & sex chromosomes Pair of homologous duplicated chromosomes 5 m Centromere Sister chromatids Metaphase chromosome
Human Karyotypes
Diploid Cells Contain Two Homologous Sets of Chromosomes Homologous pair: look alike chromosomes carry the same sequence of genes for the same traits ALLELES different versions Section 9.2 Figure 9.4
2n 6 Key Figure 13.4 Maternal set of chromosomes (n 3) Paternal set of chromosomes (n 3) Homologous chromosomes Diploid (2n = 46) Haploid (1n = 23) Sister chromatids of one duplicated chromosome Centromere Two nonsister chromatids in a homologous pair Pair of homologous chromosomes (one from each set)
Figure 8.12A/11.8 Haploid gametes (n 23) n Egg cell n Sperm cell Meiosis Fertilization Ovary Testis Diploid zygote (2n 46) 2n Multicellular diploid adults (2n 46) Mitosis Key Haploid stage (n) Diploid stage (2n)
Figure 13.6b / 11.10 Key Haploid (n) Diploid (2n) Alternation of generation Haploid multicellular organism (gametophyte) Mitosis n Mitosis n n n n Spores Gametes MEIOSIS FERTILIZATION 2n Diploid multicellular organism (sporophyte) 2n Mitosis Zygote (b) Plants and some algae
Meiosis Produces Human Gametes Section 9.8 Figure 9.16
Meiosis Produces Human Gametes Section 9.8 Figure 9.17
Meiosis Generates Variability Identical twins: embryo splits in two Each embryo then develops independently Section 9.5 Identical twins: Barbara Penoyar/Getty Images RF Figure 9.10
Figure 13.7-1 Meiosis Overview Interphase Pair of homologous chromosomes in diploid parent cell Duplicated pair of homologous chromosomes Chromosomes duplicate Sister chromatids Diploid cell with duplicated chromosomes
Figure 13.7-2 Meiosis Overview Interphase Pair of homologous chromosomes in diploid parent cell Duplicated pair of homologous chromosomes Chromosomes duplicate Reduction division Homologous chromosome separated Meiosis I Sister chromatids 1 Homologous chromosomes separate Haploid cells with duplicated chromosomes Diploid cell with duplicated chromosomes
Figure 13.7-3 Meiosis Overview Interphase Pair of homologous chromosomes in diploid parent cell Duplicated pair of homologous chromosomes Chromosomes duplicate Reduction division Homologous chromosome separated Mitotic division Sister chromatids separated Meiosis I Meiosis II Sister chromatids 1 Homologous chromosomes separate Haploid cells with duplicated chromosomes 2 Sister chromatids separate Diploid cell with duplicated chromosomes Haploid cells with unduplicated chromosomes
Figure 13.8 /11.6 and 11.7 Meiosis MEIOSIS I: Separates homologous chromosomes MEIOSIS I: Separates sister chromatids Prophase I Metaphase I Anaphase I Telophase I and Cytokinesis Prophase II Metaphase II Anaphase II Telophase II and Cytokinesis Sister chromatids Centrosome (with centriole pair) Chiasmata Spindle Centromere (with kinetochore) Metaphase plate Sister chromatids remain attached Homologous chromosomes Fragments of nuclear envelope Duplicated homologous chromosomes (red and blue) pair and exchange segments; 2n 6 in this example. Microtubule attached to kinetochore Chromosomes line up by homologous pairs. Homologous chromosomes separate Each pair of homologous chromosomes separates. Cleavage furrow Two haploid cells form; each chromosome still consists of two sister chromatids. During another round of cell division, the sister chromatids finally separate; four haploid daughter cells result, containing unduplicated chromosomes. Sister chromatids separate Haploid daughter cells forming
Figure 13.8a Prophase I Metaphase I Anaphase I Telophase I and Cytokinesis Sister chromatids Centrosome (with centriole pair) Chiasmata Spindle Centromere (with kinetochore) Metaphase plate Sister chromatids remain attached Homologous chromosomes Fragments of nuclear envelope Duplicated homologous chromosomes (red and blue) pair and exchange segments; 2n 6 in this example. Microtubule attached to kinetochore Chromosomes line up by homologous pairs. Homologous chromosomes separate Cleavage furrow Each pair of homologous chromosomes separates. Two haploid cells form; each chromosome still consists of two sister chromatids.
Interphase
Prophase I Synapsis Tetrad formation Crossing over
Figure 13.11-5 Figure 11.3 Prophase I of meiosis Pair of homologs Chiasma Nonsister chromatids held together during synapsis Crossing over TEM Anaphase I Centromere Anaphase II Daughter cells Recombinant chromosomes
Figure 11.3 Crossing Over closer look (comparison)
Metaphase I Metaphase plate Pairs line up Independent assortment 2 n 2 23 => 8 million
Figure 13.10-3 / 11.4 Independent Assortment Possibility 1 Possibility 2 Two equally probable arrangements of chromosomes at metaphase I Metaphase II Daughter cells Combination 1 Combination 2 Combination 3 Combination 4 Genetic variation video
Figure 11.4
Anaphase I Homologous chromosomes separate Sister chromatids attached
Telophase I & Cytokinesis Cleavage furrow Cell Plate 2 cells Haploid Sister chromatids attached
Interkinesis = Half Time False interphase Reformation of nucleus, nucleolus, etc. NO MORE DNA Replication!!! Temporary, if it occurs at all
Meiosis II - Prophase II Same as prophase of mitosis
Meiosis II - Metaphase II Metaphase plate Line up single file
Meiosis II - Anaphase II Sister chromatids separate
Meiosis II Telophase II & Cytokinesis 4 cells haploid variation
Figure 11.5 Prometaphase & Anaphase Comparison
Figure 13.8b Prophase II Metaphase II Anaphase II Telophase II and Cytokinesis During another round of cell division, the sister chromatids finally separate; four haploid daughter cells result, containing unduplicated chromosomes. Sister chromatids separate Haploid daughter cells forming
Figure 11.6
Figure 13.9 / 11.7 MITOSIS MEIOSIS Parent cell Chiasma MEIOSIS I Prophase Duplicated chromosome Chromosome duplication 2n 6 Chromosome duplication Prophase I Homologous chromosome pair Metaphase Metaphase I Anaphase Telophase Anaphase I Telophase I Daughter cells of meiosis I Haploid n 3 2n 2n MEIOSIS II Daughter cells of mitosis n n n n Daughter cells of meiosis II SUMMARY Property Mitosis Meiosis DNA replication Number of divisions Occurs during interphase before mitosis begins One, including prophase, metaphase, anaphase, and telophase Occurs during interphase before meiosis I begins Two, each including prophase, metaphase, anaphase, and telophase Synapsis of homologous chromosomes Number of daughter cells and genetic composition Does not occur Two, each diploid (2n) and genetically identical to the parent cell Occurs during prophase I along with crossing over between nonsister chromatids; resulting chiasmata hold pairs together due to sister chromatid cohesion Four, each haploid (n), containing half as many chromosomes as the parent cell; genetically different from the parent cell and from each other Role in the animal body Enables multicellular adult to arise from zygote; produces cells for growth, repair, and, in some species, asexual reproduction Produces gametes; reduces number of chromosomes by half and introduces genetic variability among the gametes
Figure 11.7 Meiosis & Mitosis Comparison
Spermatogenesis Spermatogenesis Puberty 4 potential sperm Acrosome cap
Oogenesis Oogenesis Prior to birth (7 month) Arrested: Prophase I Puberty Arrested: Metaphase II Fertilization Completion of meiosis Polar bodies
Ovum development
Meiosis Generates Variability Identical twins: embryo splits in two Each embryo then develops independently Section 9.5 Identical twins: Barbara Penoyar/Getty Images RF Figure 9.10
Nondisjunction Copyright McGraw-Hill Education. Permission required for reproduction or display. Anaphase I pair of homologous chromosomes pair of homologous chromosomes nondisjunction Meiosis I normal Anaphase II Meiosis II normal nondisjunction Fertilization Zygote 2n + 1 2n + 1 2n 1 2n 1 2n 2n 2n + 1 2n 1 a. b.
Nondisjuction & Fertilization
Downs syndrome trisomy 21 Copyright McGraw-Hill Education. Permission required for reproduction or display. extra chromosome 21 21 Gart gene a. b. a: Scott Wintrow/Getty Images; b: CNRI/SPL/Science Source
Downs Syndrome & Maternal Age
Klinefelter s Syndrome
Klinefelter s Syndrome
XYY Super Male
Figure 8.23A Chromosomal Alterations Deletion Inversion Duplication Reciprocal translocation Homologous chromosomes Nonhomologous chromosomes
Figure 8.23B Chromosomal Alterations Reciprocal translocation Chromosome 9 Chromosome 22 Reciprocal translocation Activated cancer-causing gene Philadelphia chromosome
Errors Also Occur Within Chromosomes Mutations in chromosome structure can have major effects on an organism. Section 9.7 Chromosomes: Addenbrookes Hospital/Science Source Figure 9.14