05--The Cell Cycle _ Mitosis

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05--The Cell Cycle _ Mitosis Powered By Docstoc
					       Honors Bio – The
     Cell Cycle & Mitosis
1.   DUE: 6.1 Study Guide Questions
2.   Catalyst: Compare and contrast the
     structure of a eukaryotic
     chromosome and prokaryotic
     chromosome. Where are they?
     How is the DNA organized?
3.   Notes: The Cell Cycle & Mitosis
4.   Activity: Onion Root Tips Cells
5.   Group Project: “Mitosis in the
     Movies”
6.   HOMEWORK: Read 6.2, 6.2 Study
     Guide Questions
Biology is the only subject in
 which multiplication is the
    same thing as division…
Making New Cells
Making New DNA
                         Where it all began
   You started as a cell smaller than the period at the end of a
    sentence….
                   Getting from there to
                                here….
   Going from egg to baby….
    the original fertilized egg has to divide…
          and divide…
                           and divide…
                                                 and divide…
                  Why Do Cells Divide?
   Reproduction
       Unicellular organisms (clones)

   Growth
       From fertilized egg to mulitcellular organism




   Repair
       Replace cells that die from normal wear and tear or from injury
                     What do dividing cells
                            need to copy?
   What has to be copied
       DNA
       organelles
       cell membrane
       lots of other
        molecules
           enzymes




                            plant cell   animal cell
Copying & packaging DNA
   When cell is ready to divide…
       copy DNA first, then…
       coil up doubled chromosomes
        like thread on a spool…
         now can move DNA around cell without having it tangle & break




                               Coil DNA into
Copying DNA                    compact chromosomes
Chromosome vs.
Duplicated Chromosome
   Duplicated chromosomes
    consists of 2 sister
    chromatids
     Narrow at their
     centromeres
     Contain identical copies
      of chromosome’s DNA
     When cell divides,
      to back to being single
      chromosomes
    Cell Cycle
    Phases
   Phases of a dividing cell’s life
       Interphase
           G1 - Cell grows
           S - Replicates DNA
           G2 - Growth & microtubules assembeled
       Mitosis - nucleus is divided into 2 nuclei
           Prophase
           Anaphase
           Metaphase
           Telophase
       Cytokinesis - cell divides cytoplasm & organelles
                                       Interphase
   90% of cell life cycle
     Cell doing it’s “everyday job”

     Prepares for duplication if
      triggered

   Characteristics
     Nucleus well-defined

     DNA loosely

      packed in long
      chromatin fibers
    Interphase
   Divided into 3 steps:
       G1 = 1st Growth
         Cell doing it’s “everyday job”
         Cell grows
       S = DNA Synthesis
         Copies DNA                       DNA
       G2 = 2nd Growth                                cell
         Prepares for division
         Cell grows
         Duplicates organelles,
          membranes                              nucleus
         Microtubules form
                                                    Mitosis
   Copying cell’s DNA & dividing it between 2 daughter nuclei
   Mitosis is divided into 4 smaller phases
       Prophase
       Metaphase
       Anaphase
       Telophase


    PMAT!!!!
Mitosis Overview
                            Cell Cycle


Interphase                                              M Phase
                                                          (DIVIDING)
(Longest, NON-DIVIDING)




G1         S          G2        Mitosis                 Cytokinesis
                                                         (Cytoplasm Division)
                                 (Nuclear Division)




              Prophase     Metaphase         Anaphase
                                                         Telophase
      Prophase
   Chromosomes coil up and

    become visible

   Centrioles move to opposite
                                  duplicated chromosomes
    ends of cell

   Mitotic spindle Forms
                                                           cell
   Nuclear envelope

    dissolves
                                               nucleus
                                                   Metaphase
   Spindle fibers align chromosomes along the
    middle of cell (Metaphase plate)
       Helps to ensure chromosomes separate properly
           So each new nucleus receives only 1 copy of each
            chromosome
                                                       Anaphase
   Centromeres divide

   The two chromatids (now called chromosomes) separate
       Pulled to opposite poles as spindle shortens

   Poles move farther apart
     Separation of Chromatids
   In anaphase, sister chromatids separate to become
    individual chromosomes again
          Telophase
   Chromosomes arrive at

    opposite poles
       Nuclear envelope forms at
        each pole
                                    Prepare to
       Chromosomes uncoil
                                     Divide!
   Spindle dissolves

   Cytokinesis begins
                                          Cytokinesis
   The division of the cytoplasm and organelles
   In animals:
       Cell membrane is pinched by belt of protein threads
           Clevage furrow

   In plants:
       Vesicles fuse at middle to form a Cell plate
       New cell wall forms on both sides
                   Cytokinesis
   Plants      Animals
                   New “daughter” cells
   Get 2 exact copies of original cells
       same DNA
       “clones”
                                                46
                                           Chromosomes




               46
          Chromosomes
                                                46
                                           Chromosomes
Onion Root Tip
   Micrograph
How Long Do Cells Live?
       Cells cannot live forever.

           Cells can only undergo a certain number of mitotic
            divisions (mitosis) before the cell dies.

               This “magic” number is programmed into the cell.

                   Genes control the life span of the
                    cell.

                       Example: Human cells only divide
                        about 40-60 times before dying
          Control of the Cell Cycle
   Regulated by feedback information
    from the cell – chemical & physical
   In eukaryotes, the cell cycle is
    controlled by many proteins
       3 Checkpoints
         End of G1 - Triggers cell division if
          favorable
         DNA Synthesis (G2) - DNA is checked
         Mitosis - Triggers the exit of mitosis

   At any of these checkpoints, cell
    division can be terminated.
                                                   Cancer
   Cancer is a disease in which cells
    grow and divide at an abnormally
    high rate.
   Cancer is a group of more than 100
    different disease that attack tissues in the
    body.

       It can occur in almost every area of the
        body; including the lungs, breast, skin,
        stomach, pancreas, colon, and even the
        heart.
                                                   Tumors
   The gradual increase in number of dividing
    cells creates a growing mass of tissues called a
    Tumor.
       There are two types of tumors:
        1. Benign: tumors that cannot spread by invasion

        2. Malignant: tumors that are capable of spreading by
            invasion
                     More Statistics
   Leading types of cancer:

       Men: Prostate Cancer

       Women: Breast Cancer


   The leading cancer killer for both men and women is
    lung cancer!

       Cancer is the 2nd leading cause of death in the United
        States (after heart disease)
    Cancer Prevention
   80% of all cancers are related to Tobacco use, poor
    diet, viruses, radiation, or exposure to other
    carcinogens (cancer-causing agents)

       Tobacco use is the most preventable cause of cancer.

           Researchers have linked smoking to cancers of the
            mouth, esophagus, lungs, larynx, bladder, kidney,
            cervix, and pancreas.
               What Causes Cancer?
1.       Genetic - propensity by heredity, breast,
         colon, prostate cancer
2.       Spontaneous - no known reason
3.       Carcinogens & mutations (chemicals that
         cause mutations)
     •     Smoking (heavy metals), asbestos, pesticides, mercury (Mad
           Hatter), lead
4.       Radiation & x-rays
5.       UV Radiation-Sunscreen!
6.       Viruses - HPV Virus & Cervical Cancer,
         Hepatitis
                   Cancer Treatment
1.   Preventative measures
2.   Self-examination
3.   Radiation - targets rapidly growing cells, good &
     bad
4.   Chemotherapy - poison, also targets growing cells
5.   Medicines - don’t always reach every cancer cell
6.   Genetic engineering - boosting T-cells, gene
     therapy
7.   Vaccines - preventing viruses that cause cancer
8.   Starving cancer-preventing blood vessel growth
Mitosis Movie – Example
                      1
Mitosis Movie – Example
                      2
Mitosis Movie –
 Story-boarding

				
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posted:3/11/2011
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