Campbell Biology, Ninth Edition, Chapter 12: The Cell Cycle PDF

LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 12 The Cell Cycle...

LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 12 The Cell Cycle Lectures by Erin Barley Kathleen Fitzpatrick © 2011 Pearson Education, Inc. Overview: The Key Roles of Cell Division The ability of organisms to produce more of their own kind best distinguishes living things from nonliving matter The continuity of life is based on the reproduction of cells, or cell division © 2011 Pearson Education, Inc.  In unicellular organisms, division of one cell reproduces the entire organism Multicellular organisms depend on cell division for – Development from a fertilized cell – Growth – Repair Cell division is an integral part of the cell cycle, the life of a cell from formation to its own division © 2011 Pearson Education, Inc. Figure 12.2 100 m (a) Reproduction 200 m (b) Growth and development 20 m (c) Tissue renewal Concept 12.1: Most cell division results in genetically identical daughter cells Most cell division results in daughter cells with identical genetic information, DNA The exception is meiosis, a special type of division that can produce sperm and egg cells © 2011 Pearson Education, Inc. Cellular Organization of the Genetic Material Genome = All DNA in a single cell – single chromosome (prokaryotes) – many chromosomes (eukaryotes) Somatic cells (nonreproductive cells) have 2 sets of 23 chromosomes in humans = 46 Gametes (reproductive cells: sperm and eggs) have half as many chromosomes as somatic cells Chromosome = strand of DNA Eukaryotic chromosomes Consist of chromatin © 2011 Pearson Education, Inc.  Eukaryotic chromosomes Consist of chromatin – Complex of DNA and protein – Condenses during cell division © 2011 Pearson Education, Inc.  Distribution of Chromosomes During Eukaryotic Cell Division In preparation for cell division, – DNA is replicated and the – chromosomes condense Each duplicated chromosome has two sister chromatids (joined copies of the original chromosome), which separate during cell division. Once separate, the chromatids are called chromosomes – The centromere is the narrow “waist” of the duplicated chromosome, where the two chromatids are most closely attached © 2011 Pearson Education, Inc. Figure 12.4 Sister chromatids Centromere 0.5 m Figure 12.5-1 Chromosomal Chromosomes DNA molecules 1 Centromere Chromosome arm Figure 12.5-2 Chromosomal Chromosomes DNA molecules 1 Centromere Chromosome arm Chromosome duplication (including DNA replication) and condensation 2 Sister chromatids Figure 12.5-3 Chromosomal Chromosomes DNA molecules 1 Centromere Chromosome arm Chromosome duplication (including DNA replication) and condensation 2 Sister chromatids Separation of sister chromatids into two chromosomes 3  Eukaryotic cell division consists of – Mitosis, the division of the genetic material in the nucleus – Cytokinesis, the division of the cytoplasm Gametes are produced by a variation of cell division called meiosis Meiosis yields – nonidentical daughter cells that – have only one set of chromosomes, – half as many as the parent cell © 2011 Pearson Education, Inc. Concept 12.2: The mitotic phase alternates with interphase in the cell cycle In 1882, the German anatomist Walther Flemming developed dyes to observe chromosomes during mitosis and cytokinesis © 2011 Pearson Education, Inc. Phases of the Cell Cycle The cell cycle consists of – Mitotic (M) phase (mitosis and cytokinesis) – Interphase (cell growth and copying of chromosomes in preparation for cell division) © 2011 Pearson Education, Inc.  Interphase (about 90% of the cell cycle) can be divided into subphases – G1 phase (“first gap”) – S phase (“synthesis”) – G2 phase (“second gap”) The cell grows during all three phases, but chromosomes are duplicated only during the S phase © 2011 Pearson Education, Inc. Figure 12.6 INTERPHASE G1 S (DNA synthesis) G2  Mitosis is conventionally divided into five phases – Prophase – Prometaphase – Metaphase – Anaphase – Telophase Cytokinesis overlaps the latter stages of mitosis BioFlix: Mitosis © 2011 Pearson Education, Inc. Figure 12.7a G2 of Interphase Prophase Prometaphase Centrosomes Fragments (with centriole Chromatin Early mitotic Aster of nuclear Nonkinetochore pairs) (duplicated) spindle envelope microtubules Centromere Plasma Nucleolus membrane Kinetochore Kinetochore Chromosome, consisting Nuclear of two sister chromatids microtubule envelope Figure 12.7b Metaphase Anaphase Telophase and Cytokinesis Metaphase Cleavage Nucleolus plate furrow forming Nuclear Spindle Centrosome at Daughter envelope one spindle pole chromosomes forming The Mitotic Spindle: A Closer Look The mitotic spindle is a structure made of microtubules that controls chromosome movement during mitosis In animal cells, assembly of spindle microtubules begins in the centrosome, the microtubule organizing center The centrosome replicates during interphase, forming two centrosomes that migrate to opposite ends of the cell during prophase and prometaphase © 2011 Pearson Education, Inc.  An aster (a radial array of short microtubules) extends from each centrosome The spindle includes the – centrosomes, – the spindle microtubules, and – the asters © 2011 Pearson Education, Inc.  During prometaphase, some spindle microtubules attach to the kinetochores of chromosomes and begin to move the chromosomes Kinetochores are protein complexes associated with centromeres At metaphase, the chromosomes are all lined up at the metaphase plate, an imaginary structure at the midway point between the spindle’s two poles © 2011 Pearson Education, Inc.  In anaphase, sister chromatids separate and move along the kinetochore microtubules toward opposite ends of the cell The microtubules shorten by depolymerizing at their kinetochore ends © 2011 Pearson Education, Inc. Figure 12.9 EXPERIMENT Kinetochore Spindle pole Mark RESULTS CONCLUSION Chromosome movement Microtubule Kinetochore Motor protein Tubulin subunits Chromosome Figure 12.9a EXPERIMENT Kinetochore Spindle pole Mark RESULTS Figure 12.9b CONCLUSION Chromosome movement Microtubule Kinetochore Motor protein Tubulin subunits Chromosome  Nonkinetochore microtubules from opposite poles overlap and push against each other, elongating the cell In telophase, genetically identical daughter nuclei form at opposite ends of the cell Cytokinesis begins during anaphase or telophase and the spindle eventually disassembles © 2011 Pearson Education, Inc. Cytokinesis: A Closer Look In animal cells, cytokinesis occurs by a process known as cleavage, forming a cleavage furrow In plant cells, a cell plate forms during cytokinesis Animation: Cytokinesis © 2011 Pearson Education, Inc. Figure 12.10a (a) Cleavage of an animal cell (SEM) 100 m Cleavage furrow Contractile ring of Daughter cells microfilaments Figure 12.10b (b) Cell plate formation in a plant cell (TEM) Vesicles Wall of parent cell 1 m forming cell plate Cell plate New cell wall Daughter cells Binary Fission in Bacteria Prokaryotes (bacteria and archaea) reproduce by a type of cell division called binary fission In binary fission, the chromosome replicates (beginning at the origin of replication), and the two daughter chromosomes actively move apart The plasma membrane pinches inward, dividing the cell into two © 2011 Pearson Education, Inc. Figure 12.12-1 Origin of Cell wall replication Plasma membrane E. coli cell Bacterial chromosome 1 Chromosome Two copies replication of origin begins. Figure 12.12-2 Origin of Cell wall replication Plasma membrane E. coli cell Bacterial chromosome 1 Chromosome Two copies replication of origin begins. 2 Replication Origin Origin continues. Figure 12.12-3 Origin of Cell wall replication Plasma membrane E. coli cell Bacterial chromosome 1 Chromosome Two copies replication of origin begins. 2 Replication Origin Origin continues. 3 Replication finishes. Figure 12.12-4 Origin of Cell wall replication Plasma membrane E. coli cell Bacterial chromosome 1 Chromosome Two copies replication of origin begins. 2 Replication Origin Origin continues. 3 Replication finishes. 4 Two daughter cells result.