Mitosis Meiosis

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MitosisMeiosis
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Mitosis

• One cell divides to make two genetically
  identical (diploid) cells
• Five stages
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase

• Mnemonics
• I.P. MAT
• upside-down TAMPI

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Interphase

• Resting period between cell divisions
• Chromosomes replicate
• Centrioles lie outside the nucleus, next to each
  other

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Prophase

• Chromosomes condense
• Each chromosome is two identical chromatids
• Spindles begin to form from the centrioles
• Nuclear envelope fragments and disperses

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Late Prophase(also known as Prometaphase)

• Centrioles move to opposite ends of the cell
• Spindle fibers from both centrioles attach to
  each chromosome
• Each centriole is attached to 46 chromosones

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Metaphase

• Chromosomes line up on metaphase plate
• Fibers begin to tug each chromosome toward
  opposite ends of the cell

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Anaphase

• Fibers pull chromatids toward opposite ends of
  the cell

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Telophase

• Chromatids (now considered chromosomes) arrive at
  opposite ends of the cell
• New nuclear membranes form

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Cytokinesis

• Movement (kinesis) of the cytoplasm (cyto)
• Rest of the cell divides
• Two genetically identical cells formed

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Meiosis

• One cell divides to make four genetically
  different haploid cells
• Ten stages

• Interphase I
• Prophase I
• Metaphase I
• Anaphase I
• Telophase I

• Interphase II
• Prophase II
• Metaphase II
• Anaphase II
• Telophase II

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Interphase I

• Same as Mitosis
• Chromosomes replicate
• Centrioles lie outside the nucleus

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Prophase I

• Same as in Mitosis, except chromosomes attach to
  nucleus in homologous pairs
• Crossing over occurs

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Crossing Over(not that show with John Edward)

• Homologous pairs exchange sections of DNA
• This can cause alleles to be separated

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Late Prophase I(also known as Prometaphase I)

• Same as Mitosis, except spindle fibers from each
  centriole attach to one chromosome of a
  homologous pair
• Each centriole is attached
• to 23 chromosones

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Metaphase I

• Same as Mitosis, except homologous pairs line up
  on either side of the metaphase plate

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Anaphase I

• Homologous pairs separate
• Chromatids do not separate

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Telophase I

• Chromosones move towards the ends of the cell
• New nuclear membranes form

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Cytokinesis I

• Same as Mitosis

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Interphase II

• Unlike in Mitosis, Chromosones do not replicate
• (already replicated)

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Prophase II

• Chromosomes condense
• Spindles form and separate
• Nuclear membrane fragments and disperses
• No crossing over

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Late Prophase II(also known as Prometaphase II)

• Centrioles move to opposite ends of the cell
• Both sides attach spindle fibers to chromosones

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Metaphase II

• Chromosomes align along the metaphase plate
• Chromosones split into chromatids and pulled to
  both ends

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Anaphase II

• Fibers pull chromatids apart and towards opposite
  ends of the cells

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Telophase II

• Chromatids arrive at either end of each cell and
  new nuclear membranes form

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Cytokinesis II

• Rest of the cells divide
• Four genetically different cells formed

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Images taken from

• http//www.pbs.org/wgbh/nova/miracle/divi_text.htm
  l
• http//www.accessexcellence.org/RC/VL/GG/crossing.
  php
• http//www.johnedwardaustralia.com/pictures.htm