Cell Cycle, Mitosis and Meiosis

Cell Cycle, Mitosis and Meiosis

Cell Cycle, Mitosis and Meiosis Covered in these slides, in the Concepts & Connections book- Chapter 8 to page 143 In Raven and Johnson Book- Chapter 10 pages192-204 And in your packet on The Cell Cycle The cell cycle multiplies cells The cell cycle is an ordered sequence of events that extends from the time a cell is first formed from a dividing parent cell until its own division. 2012 Pearson Education, Inc. Cell division is a continuum of dynamic changes During cytokinesis, the cytoplasm is divided into separate cells.

The process of cytokinesis differs in animal and plant cells. Cytokinesis Cleavage furrow Contracting ring of microfilaments Daughter cells Cleavage furrow Anchorage, cell density, and chemical growth factors affect cell division The cells within an organisms body divide and develop at different rates. Cell division is influenced externally by

the presence of essential nutrients, growth factors, proteins that stimulate division, there are over 50 different growth factors which work for one or more cell type density-dependent inhibition, in which crowded cells stop dividing, anchorage dependence, the need for cells to be in contact with a solid surface to divide. Growth factors signal the cell cycle control system The cell cycle control system is a cycling set of molecules in the cell that triggers and coordinates key events in the cell cycle. Checkpoints in the cell cycle can stop an event or signal an event to proceed.

Growth factors signal the cell cycle control system There are three major checkpoints in the cell cycle. G1- commitment to divide, growth factors present?, Size of cell ok?, G2- check for proper DNA replication M- all chromosomes attached to spindle fibers Cell Cycle progresses by action of Cdks Cyclins proteins produced by the cell during cell division Cyclin-dependent kinases (Cdk) cyclin is required to activate these enzymes activates cell proteins by phosphorylating them (proteins needed for S phase)

needed to go through G1 checkpoint MPF Maturation-promoting factor (mitosis promoting factor) aka Mitosis- promoting factor is a cyclin-Cdk complex phosphorylates proteins needed for mitosis needed to go through G2 checkpoint Rate of Cell Division Differs from one cell type to the next Examples: red bone marrow cells divide every 12 hours to replace RBCs that wear out Cells at tip of root divide about every 19 hours. Neurons (nerve cells) normally never divide again once brain is fully formed in utero Control of Division, lost = CANCER Cancer is different depending on the tissue affected

Common theme is lack of control over cell division Abnormal, uncontrolled cell division Mutation in genes (including p53) that target and control abnormal cells. Abnormal cells impede functioning of normal cells p53 gene ( tumor suppressor gene) Key role in G1 checkpoint P53 protein monitors DNA Found absent or damaged in most cancer cells Cancer is failure of cell cycle control Tumor suppressor genes- prevents the development of mutated cells, prevents

cancer/tumors Oncogenes- cancer causing genes Proto-oncogenes- normal genes that become mutated Meiosis Production/formation of __________ Basis of sexual reproduction Only germ cells undergo meiosis Haploid gametes (n 23)) n Egg cell n Sperm cell Meiosis Ovary

Fertilization Testis Diploid zygote (2n 46)) 2n Key Multicellular diploid adults (2n 46)) Mitosis Haploid stage (n) Diploid stage (2n)

How meiosis halves chromosome number INTERPHASE MEIOSIS I MEIOSIS II Sister chromatids 2 1 A pair of homologous chromosomes in a diploid parent cell

A pair of duplicated homologous chromosomes 3) MEIOSIS I: Homologous chromosomes separate INTERPHASE: Chromosomes duplicate Centrosomes (with centriole pairs) Prophase I Metaphase I

Sites of crossing over Spindle microtubules attached to a kinetochore Centrioles Anaphase I Sister chromatids remain attached Spindle Tetrad Nuclear envelope Chromatin

Sister chromatids Fragments of the nuclear envelope Centromere (with a kinetochore) Metaphase plate Homologous chromosomes separate

MEIOSIS II: Sister chromatids separate Prophase II Metaphase II Anaphase II Sister chromatids separate Telophase II and Cytokinesis Haploid daughter cells forming Meiosis Leads to Genetic Diversity Three ways genetic diversity is increased by meiosis:

1. 2 parents contribute of the genetic material to offspring 2. Crossing-over in Prophase I 3. Chromosome Alignment in Metaphase I Meiosis produces cells that are NOT identical, unique gametes Crossing Over increases genetic diversity by producing new chromosomes. C E c

e 1 Breakage of homologous chromatids C E c e 2 Tetrad (pair of homologous chromosomes in synapsis) Joining of homologous chromatids

E C Chiasma c e 3) Separation of homologous chromosomes at anaphase I C E C c

e E c e 4 Separation of chromatids at anaphase II and completion of meiosis C E C

e c E c e Parental type of chromosome Recombinant chromosome Recombinant chromosome Parental type of chromosome Gametes of four genetic types Independent orientation of chromosomes in meiosis and random fertilization lead to

varied offspring Independent orientation at metaphase I

Recently Viewed Presentations

  • Data Modeling using XML Schemas - WPI

    Data Modeling using XML Schemas - WPI

    The Entity-Relationship Model Part I. CS3431 * CS3431 * Database Design Stages Application Requirements Conceptual Design Logical Design Physical Design Conceptual Schema Logical Schema Physical Schema CS3431 * Conceptual Design What is Conceptual Design?
  • CSCE 612: VLSI System Design - Computer Science & E

    CSCE 612: VLSI System Design - Computer Science & E

    Chapter 5 — Large and Fast: Exploiting Memory Hierarchy — 5. Taking Advantage of Locality. Memory hierarchy. Store everything on disk. Copy recently accessed (and nearby) items from disk to smaller DRAM memory
  • Natural Waters - University of Vermont

    Natural Waters - University of Vermont

    Pycnocline - Density gradient change Chemocline - Chemical gradient change Ocean Chemistry Elements in the Oceans Split elemental abundances in the ocean into 3 classes: Conservative - constant Recycled - used by organisms in photic zone Scavenged - taken out...
  • MISC PICTURES - Hiram College

    MISC PICTURES - Hiram College

    Has a lot of capabilities like PCanywhere or ControlIT to allow remote administration Can be used by both good and bad hackers Can run hidden or undetected Supports encryption between attacker and victim machine Can run on any TCP or...
  • In the name of God Skeletal system session

    In the name of God Skeletal system session

    viscerocranium, or splanchnocranium. The . facial bones. are the bones of the anterior and lower skull. facial bones. include these fourteen bones: Maxilla (2) Inferior nasal concha (2) Lacrimal bones (2) Mandible. Nasal bones (2) Palatine bones (2) Vomer.
  • Grupo 29

    Grupo 29

    Si el tutor sostiene un proceso con su pupilo, no puede dar su auctoritasenun asunto, si está él interesado. Para lo cual era necesario un curador. Si el tutor ha hecho admitir una excusa temporal, es necesario durante este intervalo...
  • T t - leibniz-fli.de

    T t - leibniz-fli.de

    Referring in particular to the FCGR3 publication we can conclude, that the appearance of structural variations of the same loci in different mammalian genomes is a strong indication of genome plasticity as a general biological phenomenon and widespread impact in...
  • Anne Bradstreet - Cabarrus County Schools

    Anne Bradstreet - Cabarrus County Schools

    In the 1600's puritan writers were extremely simple to read, however now, with language changes, it is harder to comprehend. The PLAIN STYLE includes uncomplicated sentences and the use of everyday words from common speech. While Bradstreet uses figurative language...