Interphase

1
Interphase
2
Interphase

• The nondividing phase, includes most of a cells
  growth and metabolic activites.
• Is about 90 of the cell cycle.
• Is a period of intense biochemical activities
  during which the cell grows and copies its
  chromosomes in preparation for cell division.

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Interphase- Three Periods

1. G1 phase- first growth phase
2. S phase- synthesis phase occurs when DNA is
   synthesized as chromosomes are duplicated.
3. G2 phase- second growth phase

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G2 phase

• A well-defined nucleus bounded by a nuclear
  envelope.
• Two centrosomes adjacent to the nucleus.
• In animals, a pair of centrioles in each
  centrosome.
• In animals, a radial microtubular array (Aster)
  around each pair of centrioles.
• Duplicate chromosomes that cannot be
  distinguished individually due to loosely packed
  chromatin fibers.

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Prophase
6
Prophase

• Nucleolus disappears.
• Chromatin fiber condense into discrete,
  observable chromosomes, composed of two identical
  sister chromatids joined at the centromere.
• Mitotic spindle forms
• It is composed of microtubules between the two
  centrosomes .
• Centrosomes move apart, to opposite poles

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(Late Prophase)

• Nuclear membrane breaks down.
• Allows microtubules to interact with the highly
  condensed chromosomes.
• Spindle fibers extend from each pole toward the
  cells equator.
• Microtubules become attached to the centromere
  and put the chromosomes into agitated motion
• Microtubules radiate from each centrosome toward
  the equator without attaching to chromosomes

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Metaphase
9
Metaphase

• Centrosomes are position at opposite poles of the
  cell.
• Chromosomes move to the equator (metaphase
  plate).
• Centromeres of all chromosomes are aligned on the
  equator.

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Anaphase
11
Anaphase

• Sister chromatids split apart into separate
  chromosomes and move towards opposite poles of
  the cell.
• Chromosomes move in a V shape.
• The poles of the cell move farther apart,
  elongating the cell.

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Telophase
13
Telophase

• Microtubules further elongate the cell.
• Daughter nuclei begin to form at the two poles.
• Nuclear membrane forms around chromosomes
• Nucleoli reappear.
• Chromatin fiber of each chromosome uncoils and
  the chromosomes become less distinct.
• Cytokinesis has begun and the appearance of two
  separate daughter cells occurs shortly after
  mitosis is completed.

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Cytokinesis

• Process of cytoplasmic division.
• Begins during telophase.
• Animal cells
• Cleavage furrow
• Plant cells
• Cell plate