Mitosis--Cell Copying

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Mitosis--Cell Copying

• Bio 100
• Tri-County Technical College
• Pendleton, S. C.

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Ye ole cell division

• Cell division simply means one cell dividing to
  become two cells
• Process can have varied purposes and results
• 1. Can be a form of reproduction
• 2. Replacement of lost or damaged cells
• 3. Growth and maturation
• 4. Production of special types of cells

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Let me answer this one, Doc!

• Asexual reproduction DOES NOT INVOLVE the
  formation of gametes (sex cells)
• Sexual reproduction DOES involve the formation of
  gametes
• How those gametes are gotten together is another
  story and can be a real hoot!

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DNA in varied forms

• In eukaryotes, the DNA (genetic material) of a
  nondividing cell occurs in string-like, unwound
  form called CHROMATIN
• Prior to cell division, the chromatin condenses
  and super-condenses into chromosomes
• Only difference between chromatin and chromosomes
  is their FORM (arrangement)

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Let me see that again

• Chalk talk time on the composition of an
  eukaryotic chromosome
• It is composed of two SISTER CHROMATIDS joined at
  location known as CENTROMERE
• Unless mutation occurred, each contains the same
  genetic material (copies of each other)

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Intro to Mitosis and Meiosis

• Mitosis and meiosis are terms that describe
  nuclear division
• Terms apply to eukaryotic cells
• Most prokaryotes utilize binary fission (fission)
  for reproduction
• Term simply means splitting in two
• Copies genetic material and splits forming two
  cells that are clones of parent cell

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The Cell Cycle

• The life of a cell can be described with the cell
  cycle.
• After going through the cycle a set number of
  times, a cell dies.
• Mitosis is a part of the cycle.

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Phases of Cell Cycle

• G-1
• first gap phase after mitosis is finished
• DNA components are synthesized
• Synthesis Phase
• DNA is replicated
• chromosomes are replicated
• G-2
• gap phase after DNA replication

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Mitosis

• G-1, Synthesis Phase, and G-2 were considered to
  be a part of mitosis known as Interphase
• Interphase
• period of time for Gap-1, S, and Gap-2 phases
• nucleus is not dividing
• cell is getting ready to divide

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Prophase

• The chromosomes are replicated by this time and
  become visible.
• The nuclear membrane disappears.
• Duplicate chromatids attached at the centromere
• Centrioles duplicate and move to opposite poles
  of the cell.

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More on Prophase

• Microtubules are organized into a spindle
• used to move chromosomes
• Nuclear membrane disappears
• Chromatids become attached to the spindle fibers
  at their centromeres

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Chromo- somes and -tids
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Prophase
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Metaphase

• Duplicated chromosomes line up single file in the
  middle of the cell between the two centromeres.

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Anaphase

• The chromatids are separated and pulled to
  opposite ends of the dividing cell by the spindle
  fibers.
• Ana- means split

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Telophase

• Back to interphase
• nuclear membrane reforms around each set of
  chromomes
• cytoplasm is split between the new cells
• chromosomes disappear

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The End Result

• Two cells with the same chromosome number and
  genes as the original cell.
• How is genetic information preserved?
• Accurate DNA replication due to accurate base
  pairing
• Both cells go into the Gap-1 phase after
  telophase.

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Cytokinesis

• Mitosis designed to parcel genetic material
• When completed, two identical nuclei in one cell
  (excluding any mutation, of course)
• Cytokinesis needed to divide the cytoplasm and
  organelles
• Plant cell cytokinesis utilizes formation of cell
  plate which will become cell wall
• Animal cell cytokinesis utilizes cleavage
  furrow for producing daughter cells
• Wonder where they got that name?

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To test your understanding of mitosis, sketch a
cell with four chromosomes one short dark, one
short light, one long light, and one long dark
and then carry the nucleus of the cell through
mitosis.
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Works so wellbut

• A tumor is produced by mitosis gone amuck
• Something happens to the controls that regulate
  orderly cell division
• Benign tumor will not spread throughout body but
  can still be very dangerous
• Malignant tumor WILL spread to other locations by
  METASTASIS
• According to the statisticswill touch every
  family in US at one time or another

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Naming cancers

• Named according to where they originate
• Carcinomas originate in external/internal
  coverings of the body
• Sarcomas arise in tissues that support the body
  (bone/muscle)
• Leukemias and lymphomas are cancers of blood
  forming tissues such as bone marrow and lymph
  nodes
• Treatments surgery, radiation, chemotherapy,
  holistic, and charlatans