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					Cell Cycle
Interphase


G1 – rapid growth and metabolic activity
S – The chromosomes replicate
  cell structures that carry genetic info (DNA)
G2 – Centrioles replicate; cell prepares for
 division
  organelles used to separate chromosomes
Interphase
 All cells go through it
 All human cells begin with 46
  chromosomes
  23 from mom and 23 from dad
  That’s 23 pairs of homologous
   chromosomes
  Chromosome 1 from mom codes for
   the same info as 1 from dad
 At the end of interphase, each
  chromosome is double stranded
 Each strand is a chromatid
Mitosis OR Meiosis




 To separate chromosomes
  Mitosis – somatic cells
  Meiosis – gametic cells
Cytokinesis
 Cytoplasm divides
 The cell divides
 Two cells are made
  from one
Cellular Organization
 Prokaryotic               Eukaryotic


                  Somatic Cells     Gametic Cells


 Binary Fission
                      Mitosis           Meiosis
Binary Fission
 The circular
  chromosome is
  copied
 Two copies attach to
  the cell wall at
  different spots
 Cell membrane grows
  b/w chromosomes
 Cell pinches inward
  until two cells form
Eukaryotic Cells

Two kinds of division, based on cell’s job
Mitosis – for body (somatic) cells
  skin, heart, nervous, blood
Meiosis – for sex (gametic) cells
  sperm or egg (ovum)
Mitosis

Prophase – chromosomes show
Metaphase – they line up single file on the
 metaphase plate
Anaphase – they separate at the
 centromere
Telophase – they’re encased in a nuclear
 membrane; they begin to unwind
RESULT – two cells with identical genetics
Meiosis
 Pro I – chromosomes pair up in homologous
  pairs forming tetrads so crossing over can occur
Meiosis
 Metaphase I – they line up on the metaphase
  plate in tetrads
 Anaphase I – homologous chromosomes
  separate
Meiosis

Telophase I – similar to mitosis
Cells then go through another interphase
 without replicating DNA
Meiosis II (with Pro II, Met II, Ana II, Telo II)
 is the same as Mitosis
RESULT – 4 cells with different genetic
 information
Mitosis v. Meiosis
                     http://library.thinkquest.
                       org/C004535/mitosis_
                       vs_meiosis.html
                     Mitosis cells are Diploid
                       (2N): all
                       chromosomes are in
                       pairs
                     Meiosis cells are
                       Haploid (N): all
                       chromosomes are in
                       singles

				
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posted:3/13/2013
language:English
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