Chapter 10 and 11 Mitosis and Meiosis - Tagged PDF

Because learning changes everything. ® Chapter 10 How Cells Divide BIOLOGY Thirteenth Edition Raven, Johnson, Mason, Losos, Duncan © 2023 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or furthe...

Because learning changes everything. ® Chapter 10 How Cells Divide BIOLOGY Thirteenth Edition Raven, Johnson, Mason, Losos, Duncan © 2023 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw Hill, LLC.  Lecture Outline 10.3 Overview of the Eukaryotic Cell Cycle 10.4 Interphase: Preparation for Mitosis 10.5 M Phase: Chromosome Segregation and the Division of Cytoplasmic Contents Stem Jems/Science Source © McGraw Hill, LLC 2  Learning Objectives Chapter 10 How Cells Divide 10.3 Overview of the Eukaryotic Cell Cycle 1. Describe the eukaryotic cell cycle. 10.4 Interphase: Preparation for Mitosis 2. Describe the events that take place during interphase. 3. Illustrate the connection between sister chromatids after S phase. 10.5 M Phase: Chromosome Segregation and the Division of Cytoplasmic Contents 4. Describe the phases of mitosis. 5. Explain the importance of metaphase. 6. Compare cytokinesis in plants and animals. © McGraw Hill, LLC 3 Because learning changes everything. ®  Because learning changes everything. ® Chromosomes In eukaryotes, the hereditary information within the nucleus is distributed among individual, linear DNA molecules DNA molecules combine with proteins that stabilize the DNA molecules, assist in packaging DNA during cell division, and influence the expression of individual genes In a cell, each chromosome is composed of one DNA molecule and its associated proteins  Because learning changes everything. ® Chromosomes The chromosome complement = the complete set of chromosomes of a eukaryotic organism. The nucleus of each somatic cell contains a fixed number of chromosomes typical of the particular species. The number of chromosomes vary tremendously among species and have little relationship to the complexity of the organism.  Because learning changes everything. ® Somatic Chromosome Number Human 46 Garden pea 14 Fruit fly 8 Yeast 32 Dog 78 Mouse 40 Chicken 78 Bracken fern 116  Eukaryotic Cell Cycle 1. G1 (gap phase 1) Primary growth phase, longest phase 2. S (synthesis) Interphase Replication of DNA 3. G2 (gap phase 2) Organelles replicate, microtubules organize 4. M (mitosis) Subdivided into 5 phases. 5. C (cytokinesis) Separation of 2 new cells. Access the text alternative for slide images. © McGraw Hill, LLC 8  Duration Time it takes to complete a cell cycle varies greatly Fruit fly embryos = 8 minutes Mature cells take longer to grow Typical mammalian cell takes 24 hours. Liver cell takes more than a year. Growth occurs during G1, G2, and S phases M phase takes about an hour. Most variation in length of G1 Resting phase G0 – cells spend more or less time here. © McGraw Hill, LLC 9  Cell Cycle Figure 10.8 Access the text alternative for slide images. © McGraw Hill, LLC 10  Chromosomes & DNA Molecules in the Mitotic cell cycle © McGraw Hill, LLC  Interphase G1, S, and G2 phases G1 – cells undergo major portion of growth. S – replicate DNA. G2 – chromosomes coil more tightly using motor proteins; centrioles replicate; tubulin synthesis. Centromere – point of constriction Kinetochore – attachment site for microtubules. Each sister chromatid has a centromere. Chromatids stay attached at centromere by cohesin. Replaced by condensin in multicellular animals. © McGraw Hill, LLC 12  Kinetochores Figure 10.9 Access the text alternative for slide images. © McGraw Hill, LLC 13  Protein Found at the Centromere Courtesy of Peter Lenart and Jan-Michael Peters Access the text alternative for slide images. © McGraw Hill, LLC 14  Interphase Cellular Organization Andrew S. Bajer, University of Oregon Figure 10.11 Access the text alternative for slide images. © McGraw Hill, LLC 15  M phase Mitosis is divided into five phases: 1. Prophase 2. Prometaphase 3. Metaphase 4. Anaphase 5. Telophase © McGraw Hill, LLC 16  Prophase Individual condensed chromosomes first become visible with the light microscope Condensation continues throughout prophase. Spindle apparatus assembles Two centrioles move to opposite poles forming spindle apparatus (no centrioles in plants). Asters – radial array of microtubules in animals (not plants). Nuclear envelope breaks down © McGraw Hill, LLC 17  Prophase Cellular Organization Andrew S. Bajer, University of Oregon Figure 10.11 Access the text alternative for slide images. © McGraw Hill, LLC 18  Prometaphase Transition occurs after disassembly of nuclear envelope Microtubule attachment 2nd group grows from poles and attaches to kinetochores. Each sister chromatid connected to opposite poles. Chromosomes begin to move to center of cell – congression Assembly and disassembly of microtubules. Motor proteins at kinetochores. © McGraw Hill, LLC 19  Prometaphase Cellular Organization Andrew S. Bajer, University of Oregon Figure 10.11 Access the text alternative for slide images. © McGraw Hill, LLC 20  Metaphase Alignment of chromosomes along metaphase plate Not an actual structure. Future axis of cell division. Figure 10.12 Andrew S. Bajer, University of Oregon © McGraw Hill, LLC 21  Metaphase cellular organization Andrew S. Bajer, University of Oregon Figure 10.11 Access the text alternative for slide images. © McGraw Hill, LLC 22  Anaphase Begins when centromeres split Key event is removal of cohesin proteins from all chromosomes Sister chromatids pulled to opposite poles Two forms of movements: 1. Anaphase A – kinetochores pulled toward poles 2. Anaphase B – poles move apart Dr. Jeremy Pickett-Heaps Access the text alternative for slide images. © McGraw Hill, LLC 23  Anaphase Cellular Organization Andrew S. Bajer, University of Oregon Figure 10.11 Access the text alternative for slide images. © McGraw Hill, LLC 24  Telophase Spindle apparatus disassembles Nuclear envelope forms around each set of sister chromatids Now called chromosomes. Chromosomes begin to uncoil Nucleolus reappears in each new nucleus © McGraw Hill, LLC 25  Telophase Cellular Organization Andrew S. Bajer, University of Oregon Figure 10.11 Access the text alternative for slide images. © McGraw Hill, LLC 26  Cytokinesis Cleavage of the cell into equal halves Animal cells – constriction of actin filaments produces a cleavage furrow Plant cells – cell plate forms between the nuclei Fungi and some protists – nuclear membrane does not dissolve; mitosis occurs within the nucleus; division of the nucleus occurs with cytokinesis © McGraw Hill, LLC 27  Animal Cell Cytokinesis (a) Don W. Fawcett/Science Source; (b) Guenter Albrecht-Buehler, Northwestern University, Chicago Figure 10.14 Access the text alternative for slide images. © McGraw Hill, LLC 28  Plant Cell Cytokinesis ©Biophoto Associates/Science Source Figure 10.15 Access the text alternative for slide images. © McGraw Hill, LLC 29  Lecture Outline Chapter 11 11.1 Sexual Reproduction Requires Meiosis 11.3 The Process of Meiosis 11.4 Summing Up: Meiosis Versus Mitosis Steven P. Lynch © McGraw Hill, LLC 30  Chapter 11 Sexual Reproduction and Meiosis 11.1 Sexual Reproduction Requires Meiosis 1. Characterize the function of meiosis in sexual reproduction. 2. Distinguish between germ-line and somatic cells. 11.3 The Process of Meiosis 3. Describe the behavior of chromosomes through both meiotic divisions. 4. Explain the importance of monopolar attachment of homologous pairs at metaphase I. 5. Differentiate between the events of anaphase I and anaphase II of meiosis. 11.4 Summing Up: Meiosis Versus Mitosis 6. Describe the distinct features of meiosis. 7. Describe the differences in chromatid cohesion in meiosis and mitosis. 8. Explain the importance of the suppression of replication between meiotic divisions. © McGraw Hill, LLC 31  Sexual life cycles Composed of meiosis and fertilization Diploid cells Somatic (nonreproductive) cells of adults have 2 sets of chromosomes. Haploid cells Gametes (eggs and sperm) have only 1 set of chromosomes. Offspring inherit genetic material from 2 parents © McGraw Hill, LLC 32  Diploid cells carry chromosomes from two parents Access the text alternative for slide images. © McGraw Hill, LLC 33  Sexual reproduction Reproduction that involves an alternation of meiosis (diploid → haploid) and fertilization (haploid → diploid) is called sexual reproduction Some life cycles include longer diploid phases (For example mammals), some include longer haploid phases (For example fungi) In most animals, diploid state dominates Single-cell diploid zygote undergoes mitosis to produce diploid somatic cells Some diploid cells undergo meiosis to produce haploid gametes (called germ-line cells) © McGraw Hill, LLC 34  The sexual life cycle in humans Access the text alternative for slide images. © McGraw Hill, LLC 35  Features of Meiosis 1 Meiosis includes two rounds of division Meiosis I and meiosis II Each round has prophase, metaphase, anaphase, and telophase stages Synapsis Occurs early in prophase I Homologous chromosomes become closely associated Includes formation of synaptonemal complexes Complexes also called tetrad or bivalents © McGraw Hill, LLC 36  Formation of a bivalent Access the text alternative for slide images. © McGraw Hill, LLC 37  Features of Meiosis 2 While homologues are paired during prophase I genetic recombination (crossing over) occurs Sites of crossing over are called chiasmata First meiotic division is termed the “reduction division” Results in daughter cells that contain one homologue from each chromosome pair No DNA replication between meiotic divisions Second meiotic division does not further reduce the number of chromosomes Separates the sister chromatids for each homologue © McGraw Hill, LLC 38  The Process of Meiosis Meiotic cells have an interphase Meiosis I period that is similar to mitosis with G1, S, and G2 phases Prophase I Metaphase I After interphase, germ-line cells enter Anaphase I meiosis I Telophase I Meiosis II Prophase II Metaphase II Anaphase II Telophase II © McGraw Hill, LLC 39  Prophase I Chromosomes coil tighter and become visible, nuclear envelope disappears, spindle forms Each chromosome is composed of two sister chromatids Synapsis Sites of crossing over form Access the text alternative for slide images. Ed Reschke/Photolibrary/Getty Images © McGraw Hill, LLC 40  Crossing over 1 Genetic recombination between non-sister chromatids Allows the homologues to exchange chromosomal material Alleles of genes that were formerly on separate homologues can now be found on the same homologue Chiasmata – site of crossing over Contact maintained until anaphase I © McGraw Hill, LLC 41  Crossing over 2 Access the text alternative for slide images. © McGraw Hill, LLC 42  Metaphase I Paired homologues locked together following crossing over Microtubules from opposite poles attach to each homologue Do not attach to each sister chromatid as in mitosis Homologues are aligned at the metaphase plate side-by-side Orientation of each pair of homologues on the spindle is random Access the text alternative for slide images. Ed Reschke/Photolibrary/Getty Images © McGraw Hill, LLC 43  Random orientation of chromosomes Access the text alternative for slide images. © McGraw Hill, LLC 44  Anaphase I Microtubules of the spindle shorten Chiasmata break Homologues are separated from each other and move to opposite poles Sister chromatids remain attached at centromeres Each pole has a complete haploid set of chromosomes Independent assortment of maternal and paternal chromosomes Access the text alternative for slide images. Ed Reschke/Photolibrary/Getty Images © McGraw Hill, LLC 45  Telophase I Nuclear envelope re-forms around each daughter nucleus Homologous chromosomes are separated Sister chromatids are no longer identical due to crossing over Cytokinesis may or may not occur after telophase I Meiosis II occurs after an interval of variable length Access the text alternative for slide images. Ed Reschke/Photolibrary/Getty Images © McGraw Hill, LLC 46  Meiosis II Resembles a mitotic division Prophase II: nuclear envelopes dissolve and new spindle apparatus forms Metaphase II: chromosomes align on metaphase plate Anaphase II: sister chromatids are separated from each other Telophase II: nuclear envelope re-forms around 4 sets of daughter chromosomes; cytokinesis follows © McGraw Hill, LLC 47  Prophase II Brief duration compared to prophase I (true of all meiosis II phases) A new spindle apparatus forms in each cell The nuclear envelope breaks down Access the text alternative for slide images. Ed Reschke/Photolibrary/Getty Images © McGraw Hill, LLC 48  Metaphase II Chromosomes consisting of sister chromatids joined at the centromere align along the metaphase plate in each cell Kinetochore microtubules from opposite poles attach to kinetochores of sister chromatids Access the text alternative for slide images. Ed Reschke/Photolibrary/Getty Images © McGraw Hill, LLC 49  Anaphase II Kinetochore microtubules shorten Sister chromatids (not homologs) are pulled to opposite poles of the cells Access the text alternative for slide images. Ed Reschke/Photolibrary/Getty Images © McGraw Hill, LLC 50  Telophase II Nuclear membranes re-form around four different clusters of chromosomes After cytokinesis, four haploid cells result Access the text alternative for slide images. Ed Reschke/Photolibrary/Getty Images © McGraw Hill, LLC 51  Final result of meiosis Four cells containing haploid sets of chromosomes In animals, develop directly into gametes In plants, fungi, and many protists, divide mitotically Produce greater number of gametes Adults with varying numbers of chromosome sets © McGraw Hill, LLC 52  Errors in Meiosis Nondisjunction – failure of chromosomes to move to opposite poles during either meiotic division Aneuploid gametes – gametes with missing or extra chromosomes Result of nondisjunction events Most common cause of spontaneous abortion in humans © McGraw Hill, LLC 53  Meiosis versus Mitosis Meiosis is characterized by four distinct features: 1. Homologous pairing and crossing over 2. Sister chromatids remain joined at their centromeres and segregate together during anaphase I 3. Kinetochores of sister chromatids attach to the same pole in meiosis I 4. DNA replication is suppressed between meiosis I and meiosis II © McGraw Hill, LLC 54  Alignment of chromosomes differs between meiosis I and mitosis Access the text alternative for slide images. © McGraw Hill, LLC 55  Comparison of meiosis and mitosis 1 Access the text alternative for slide images. © McGraw Hill, LLC 56  Comparison of meiosis and mitosis 2 Access the text alternative for slide images. © McGraw Hill, LLC 57  Homologous pairing specific to meiosis How homologues find each other and become aligned is not understood Sister chromatid cohesion is similar to that in mitosis, but involves meiosis-specific cohesin proteins Replacement of mitotic Scc1 protein as part of the meiosis-specific cohesin complex is common feature of studied meiotic systems Synaptonemal complex proteins have been identified in diverse species, but proteins show little sequence conservation © McGraw Hill, LLC 58  Centromeres of sister chromatids remain connected Key distinction between meiosis and mitosis is the: maintenance of sister chromatid cohesion at the centromere during all of meiosis I loss of cohesion from the chromosome arms during anaphase I Protein called Shugoshin protects cohesin from separase- mediated cleavage during meiosis I © McGraw Hill, LLC 59  Sister kinetochores attach to the same pole during meiosis I Kinetochores of sister chromatids must be attached to the same pole in meiosis I, in contrast to mitosis and meiosis II Basis of monopolar attachment seems to be based on structural differences between centromere-kinetochore complexes in meiosis I and in mitosis © McGraw Hill, LLC 60  Replication is suppressed between meiotic divisions Detailed mechanisms of suppression of replication between meiotic divisions is not known Cyclin B is lost completely between mitotic divisions, but not between meiotic divisions Seems to prevent replication initiation complexes from forming © McGraw Hill, LLC 61  Meiosis produces cells that are not identical Because of random orientation of chromosomes at first meiotic division, and because of crossing over, meiosis rarely produces cells that are identical Resulting variation is essential for evolution Sexually reproducing populations have much greater genetic variation than asexually reproducing ones © McGraw Hill, LLC 62  End of Main Content Because learning changes everything. ® www.mheducation.com © 2023 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom. © McGraw Hill, LLC No reproduction or further distribution permitted without the prior written consent of McGraw Hill, LLC.