Cell Division and Mitosis

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Cell Division and Mitosis
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Cell Division

• GROWTH of AN ORGANISM
• BUILD and REPAIR OLDER CELLS
• For the total number of cells to increase cells
  must undergo CELL DIVISION!!!
• Cell Divisionwhen a parent cell produces
  identical daughter cells.
• Each second another 25 million cells have just
  finished dividing to create 2 cells.

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Cell DivisionAn Amazing Process!!!

• Involves the duplication and sorting of
  chromosomes into two identical sets
• Occurs in 6 continuous stages interphase,
  prophase, metaphase, anaphase, telophase, and
  cytokinesis
• IPMATC

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Life Spans of Different Human Cells







BRAIN CELLS
30-50 YEARS
RED BLOOD CELLS
120 DAYS
STOMACH LINING
10 DAYS
2 DAYS
PLATELETS
LIVER CELLS
200 DAYS
INTESTINAL CELLS
3 DAYS
SKIN CELLS
20 DAYS
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Cell Cyclesequence of growth and division of a
cell
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Interphase Gap 1 Stage

• Chromosomes not visible
• Cell growth/protein production
• Cell development

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What is this DNA stuff?
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Interphase S Stage (DNA synthesis)

• Chromosomes copied (sister chromatids held
  together by centromere)

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Interphase Gap 2 Stage

• Chromosomes coil
• Protein synthesis needed for cell division
• Centrioles replicate

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Mitotic Stage

• Formation of two identical nuclei
• 4 stages
• Prophase
• Metaphase
• Anaphase
• Telophase
• Cytoplasm divides after mitosis (cytokinesis)

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Regular cell before division

• Nucleus

• Chromatin (coiled DNA) (fancy name for
  chromosome!!!)

• Centriole

How many chromosomes?
6
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First Stage of Cell Division--Interphase

• No chromosomes visible yet just thread-like
  coils called chromatin
• Centrioles present outside the nucleus
• Chromatin duplicates (copy of DNA is produced)
• Chromatin condensesforms chromatid
• Duplicate is called sister chromatid
• Is attached to centromere creating a chromosome

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Interphase

• Centromere

• Double-stranded chromosome (made of 2 sister
  chromatids

• Centriole

How many chromatids?
12
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Photo of cell in interphase
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Beginning of Mitosis--Prophase

• Centrioles move to opposite poles (ends) of the
  cell
• Mesh-like spindle forms (bridge between ends of
  cells)
• Nuclear membrane dissolves

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Prophase

• Centriole

• Centromere

• Spindle fibers

• Chromosome (chromatids)

• Aster

How many chromosomes?
6-doubled stranded
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Photo of cell in prophase
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Metaphase

• Chromosomes line up at the equator and attach
  to spindle fibers at the centromere

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Metaphase
How many chromosomes?
6 double-stranded
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Photo of cell in metaphase
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Anaphase

• Centromere splits, allows chromosome to separate
  into 2 sister chromatids
• Chromosomes pulled towards centrioles along
  spindle fibers.

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Anapahse

• Chromosome (chromatids) being pulled away from
  each other towards opposite poles

How many chromosomes?
12, but 6 going opposite direction
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TelophaseEnd of Mitosis

• Chromosomes coil again, begin to resemble
  chromatin cannot be seen under microscope
• Nuclear membrane forms around chromatin
• Nucleolus reappears

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Photo of cell in anaphase
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Telophase
How many chromosomes?
6 in each new nucleus
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Photo of cell in telophase
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Cytokinesis2 new cells

• Cytokinesisthe actual division of the cells
• Cell membrane moves inward, pinches the cytoplasm
  into 2 equal parts
• Each part contains a nucleus with IDENTICAL
  CHROMOSOMES

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Regular cells after division
Regular cells after division
2 new identical cells!!!
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Phases of mitosisI(PMAT)C
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Mitosis Can you name the stages?
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Animal vs. Plant Cell Division

• ANIMAL CELL
• Centriole and aster present
• Daughter cells separated by cleavage furrow

• PLANT CELL
• No visible centriole or aster
• Daughter cells separated by cell plate

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Duplicated Chromosome