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52 ch11mitosis2008

52 ch11mitosis2008






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  • Unicellular organisms Cell division = reproduction Reproduces entire organism& increase population Multicellular organisms Cell division provides for growth & development in a multicellular organism that begins as a fertilized egg Also use cell division to repair & renew cells that die from normal wear & tear or accidents
  • Centromeres are segments of DNA which have long series of tandem repeats = 100,000s of bases long. The sequence of the repeated bases is quite variable. It has proven difficult to sequence.
  • Microtubules are NOT reeled in to centrioles like line on a fishing rod. The motor proteins walk along the microtubule like little hanging robots on a clothes line. In dividing animal cells, non-kinetochore microtubules are responsible for elongating the whole cell during anaphase, readying fro cytokinesis
  • Division of cytoplasm happens quickly.
  • Prokaryotes (bacteria) No nucleus; single circular chromosome. After DNA is replicated, it is partitioned in the cell. After cell elongation, FtsZ protein assembles into a ring and facilitates septation and cell division. Protists (dinoflagellates) Nucleus present and nuclear envelope remains intact during cell division. Chromosomes linear. Fibers called microtubules, composed of the protein tubulin, pass through tunnels in the nuclear membrane and set up an axis for separation of replicated chromosomes, and cell division. Protists (diatoms) A spindle of microtubules forms between two pairs of centrioles at opposite ends of the cell. The spindle passes through one tunnel in the intact nuclear envelope. Kinetochore microtubules form between kinetochores on the chromosomes and the spindle poles and pull the chromosomes to each pole. Eukaryotes (yeast) Nuclear envelope remains intact; spindle microtubules form inside the nucleus between spindle pole bodies. A single kinetochore microtubule attaches to each chromosome and pulls each to a pole. Eukaryotes (animals) Spindle microtubules begin to form between centrioles outside of nucleus. As these centrioles move to the poles, the nuclear envelope breaks down, and kinetochore microtubules attach kinetochores of chromosomes to spindle poles. Polar microtubules extend toward the center of the cell and overlap.

52 ch11mitosis2008 52 ch11mitosis2008 Presentation Transcript

  • Biology is the only subject in which multiplication is the same thing as division…AP Biology 2007-2008
  • The Cell Cycle: Cell Growth, Cell DivisionAP Biology 2007-2008
  • Where it all began… You started as a cell smaller than a period at the end of a sentence…AP Biology
  • And now look at you… How did you get from thereAP Biology to here?
  • Getting from there to here…  Going from egg to baby…. the original fertilized egg has to divide… and divide… and divide… and divide…AP Biology
  • Why do cells divide?  For reproduction  asexual reproduction  one-celled organisms  For growth  from fertilized egg to multi-celled organism amoeba  For repair & renewal  replace cells that die from normal wear & QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. tear or from injuryAP Biology
  • Making new cells  Nucleus  chromosomes  DNA  Cytoskeleton  centrioles  in animals  microtubule spindle fibersAP Biology
  • DNA Nucleus  Function chromosome protects DNA  histone protein  Structure  nuclear envelope  double membrane  membrane fused in spots to create pores  allows large macromolecules to pass through nuclear pores nuclear pore What kind of molecules need to pass through? nucleolusAP Biology nuclear envelope
  • AP Biology
  • Cytoskeleton  Function  structural support  maintains shape of cell  provides anchorage for organelles  protein fibers  microfilaments, intermediate filaments, microtubules  motility  cell locomotion  cilia, flagella, etc.  regulation  organizes structures & activities of cellAP Biology
  • Cytoskeleton  actin  microtubule  nucleiAP Biology
  • Centrioles  Cell division  in animal cells, pair of centrioles organize microtubules  spindle fibers  guide chromosomes in mitosisAP Biology
  • End of the TourAP Biology
  • Getting the right stuff  What is passed on to daughter cells?  exact copy of genetic material = DNA  mitosis  organelles, cytoplasm, cell membrane, enzymes  cytokinesis chromosomes (stained orange) in kangaroo rat epithelial cell →notice cytoskeleton fibersAP Biology
  • I.P.M.A.T. Overview of mitosis interphase prophase (pro-metaphase) cytokinesisAP Biology metaphase anaphase telophase
  • Interphase  90% of cell life cycle  cell doing its “everyday job”  produce RNA, synthesize proteins/enzymes  prepares for duplication if triggered I’m working here! Time to divide & multiply!AP Biology
  • M Mitosis Cell cycle G2 Gap 2 G1  Cell has a “life cycle” Gap 1 G0 cell is formed from S Resting a mitotic division Synthesiscell grows & matures cell grows & matures to divide again to never divide again G1, S, G2, M liver cells G1→G0 epithelial cells, brain / nerve cells blood cells, muscle cells stem cellsAP Biology
  • Interphase  Divided into 3 phases: G0  G1 = 1st Gap (Growth)  cell doing its “everyday job” o  cell grows n al tesig ivid  S = DNA Synthesis d  copies chromosomes  G2 = 2nd Gap (Growth)  prepares for division  cell grows (more)  produces organelles, proteins, membranesAP Biology
  • green = key features Interphase  Nucleus well-defined  DNA loosely packed in long chromatin fibers  Prepares for mitosis  replicates chromosome  DNA & proteins  produces proteins & organellesAP Biology
  • S phase: Copying / Replicating DNA  Synthesis phase of Interphase  dividing cell replicates DNA  must separate DNA copies correctly to 2 daughter cells  human cell duplicates ~3 meters DNA  each daughter cell gets complete identical copy  error rate = ~1 per 100 million bases  3 billion base pairs in mammalian genome  ~30 errors per cell cycle  mutations (to somatic (body) cells)AP Biology
  • ACTGGTCAGGCAATGTC DNA Organizing DNA  DNA is organized in chromosomes histones  double helix DNA molecule  wrapped around histone proteins  like thread on spools  DNA-protein complex = chromatin chromatin  organized into long thin fiber  condensed further during mitosis double stranded chromosomeAP Biology duplicated mitotic chromosome
  • Copying DNA & packaging it…  After DNA duplication, chromatin condenses  coiling & folding to make a smaller package DNA mitotic chromosome chromatinAP Biology
  • double-strandedmitotic humanchromosomesAP Biology
  • Mitotic Chromosome  Duplicated chromosome  2 sister chromatids  narrow at centromeres  contain identical copies of original DNA homologous homologouschromosomes chromosomes sister chromatidssingle-stranded AP Biology double-stranded homologous = “same information”
  • Mitosis  Dividing cell’s DNA between 2 daughter nuclei  “dance of the chromosomes”  4 phases  prophase  metaphase  anaphase  telophaseAP Biology
  • green = key features Prophase  Chromatin condenses  visible chromosomes  chromatids  Centrioles move to opposite poles of cell  animal cell  Protein fibers cross cell to form mitotic spindle  microtubules  actin, myosin  coordinates movement of chromosomes  Nucleolus disappears  Nuclear membrane breaks downAP Biology
  • green = key features Transition to Metaphase  Prometaphase  spindle fibers attach to centromeres  creating kinetochores  microtubules attach at kinetochores  connect centromeres to centrioles  chromosomes begin movingAP Biology
  • green = key features Metaphase  Chromosomes align along middle of cell  metaphase plate  meta = middle  spindle fibers coordinate movement  helps to ensure chromosomes separate properly  so each new nucleus receives only 1 copy of each chromosomeAP Biology
  • AP Biology
  • green = key features Anaphase  Sister chromatids separate at kinetochores  move to opposite poles  pulled at centromeres  pulled by motor proteins “walking”along microtubules  actin, myosin  increased production of ATP by mitochondria  Poles move farther apart  polar microtubules lengthenAP Biology
  • Separation of chromatids  In anaphase, proteins holding together sister chromatids are inactivated  separate to become individual chromosomes 1 chromosome 2 chromosomes 2 chromatids single-strandedAP Biologydouble-stranded
  • Chromosome movement  Kinetochores use motor proteins that “walk” chromosome along attached microtubule  microtubule shortens by dismantling at kinetochore (chromosome) endAP Biology
  • green = key features Telophase  Chromosomes arrive at opposite poles  daughter nuclei form  nucleoli form  chromosomes disperse  no longer visible under light microscope  Spindle fibers disperse  Cytokinesis begins  cell divisionAP Biology
  • Cytokinesis  Animals  constriction belt of actin microfilaments around equator of cell  cleavage furrow forms  splits cell in two  like tightening a draw stringAP Biology
  • Cytokinesis in Animals(play Cells Alive movies here)(playBiology AP Thinkwell movies here)
  • Mitosis in whitefish blastulaAP Biology
  • Mitosis in animal cellsAP Biology
  • Cytokinesis in Plants  Plants  cell plate forms  vesicles line up at equator  derived from Golgi  vesicles fuse to form 2 cell membranes  new cell wall laid down between membranes  new cell wall fuses with existing cell wallAP Biology
  • Cytokinesis in plant cellAP Biology
  • Mitosis in plant cellAP Biology
  • onion root tipAP Biology
  • Origin of replication Evolution of mitosis chromosome:  Mitosis in double-stranded replication DNA of DNA eukaryotes likely evolved from binary fission in elongation of cell bacteria  single circular ring of proteins chromosome  no membrane- bound organelles cell pinches in twoAP Biology
  • prokaryotes (bacteria) Evolution of mitosis protists dinoflagellates  A possible progression of mechanisms protists diatoms intermediate between binary fission & mitosis eukaryotes yeast seen in modern organisms eukaryotes animalsAP Biology
  • Dinoflagellates  algae  “red tide”  bioluminescenceAP Biology
  • Diatoms  microscopic algae  marine  freshwaterAP Biology
  • Any Questions??AP Biology 2007-2008
  • Ghosts of Lectures Past (storage)AP Biology 2007-2008
  • Control of Cell CycleAP Biology
  • Kinetochore  Each chromatid has own kinetochore proteins  microtubules attach to kinetochore proteinsAP Biology
  • Chromosome structure scaffold chromatin loop protein n m 30 DNA nucleosome histone rosettes of chromatin loopschromosome DNA double helixAP Biology
  • M metaphase anaphase Cell Division cycle prophase telophase C G2  Phases of a dividing cell’s life interphase (G1, S, G2 phases) mitosis (M)  interphase S cytokinesis (C) G1  cell grows  replicates chromosomes  produces new organelles, enzymes, membranes…  G1, S, G2  mitotic phase  cell separates & divides chromosomes  mitosis  cell divides cytoplasm & organelles  cytokinesisAP Biology
  • Substitute Slides for Student Print version (for student note-taking)AP Biology 2007-2008
  • And now look at you… How did you get from thereAP Biology to here?