Mitosis vs. Meiosis No sex vs. Sex

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Mitosis vs. Meiosis No sex vs. Sex

• Which is better?
• Mr. Snider
• SOCESsocesbio.com

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Why do Mitosis?

• Growth 1 cell to billions exponentially
• Maintenance replace skin, stomach
• Repair- injuries

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Why do Meiosis?

• Variation not FUN
• Remember over 50 of sexual reproduction does not
  include intercourse

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Mitosis vs. Meiosis

• One cell forms 2 exact copies
• 100 of DNA same
• Represent all genes in gene pool
• Clones
• Susceptible to same diseases

• 1 cell forms 4 daughter cells, each with ½ the
  original of chromosomes
• Genetic recombination
• Increase variation
• New combinations

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Quick video comparison
http//www.youtube.com/watch?vBa9LXKH2ztU
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Physical structure vs. genetics

• Physically Meiosis and Mitosis are similar
• IPMAT
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase (Cytokenesis)

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Mitosis preview bear with 5 mins

• Awesome video

http//www.youtube.com/watch?vQ6ucKWIIFmg
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Interphase

• Common to both Mitosis and Meiosis
• DNA and organelles copy themselves
• G1 growth 1 recovery (stop and stay)
• S synthesis -copying
• G2 growth 2 get beg for copying (stop)

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Prophase

• Chromatin condenses to become visible as
  chromosomes (sister chromatids)
• Nuclear envelope breaks apart
• Spindle apparatus (spindle fibers and centrosome)
  forms
• spindle fibersmicrotubules
• Animal cell centrosome includes centromere

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Metaphase

• Sister chromatids line up in the center of the
  cell
• (spindle apparatus is fully formed)

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Anaphase

• Sister chromatids separate, and chromosomes
  (chromatids) move to the poles

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Telophase (cytokenesis)

• Spindle apparatus dissolves
• Nuclear envelope reforms
• Chromosomes dissolve into chromatin
• Cytokenesis even division of organelles between
  daughter cells
• Cleavage plane in animals
• Cell plate in plants

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Summary Mitosis

• One cell forming 2 identical daughter cells
• Growth, Maintenance, repair
• Zygote- you 1000X
• Cloning Asexual
• Reproduction yeast? single celled protists
  (not bacteria binary fission)

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Review Mitosis
http//www.youtube.com/watch?vkRWnJd1WRbA
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Main Differences

• Mieosis variation for offspring- gene reduction
• Mitosis perfect copies to get big enough to do
  reproduction
• Question which needs more energy?
• How many times to do reproduction?

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Meiosis

• Diploid cell to haploid gamete
• Diploid 2 copies of chromosomes(2N)
• Haploid 1 copy (N or 1N)
• If you add 2N2N during sex BAD things happen, so
  you must reduce 1st
• 2 times Interphase Meiosis 1 (P-T) Meiosis 2
  (P-T) 9 phases
• DNA changes only physical parts same)

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Interphase

• Same as in Mitosis DNA and organelles double
  (DNA during S phase)

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Meiosis I

• Prophase Tetrads become visible
• Tetrad Homologous pair or Homologous chromatids
• 2 pairs of sister chromatids that have same genes
  from different parents
• Crossing over occurs here

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Metaphase I

• Tetrads line up in center of cell

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Anaphase I

• Tetrads (2 N) separate and Sister chromatids/
  Homologous pairs (N) move to the poles
• This is tricky you only have one set of
  chromosomes, but 2 copies of that set

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Telophase I

• Homologous pairs/ Sister Chromatids sometimes
  uncondense (most dont- loss of Energy)

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Interphase II

• Its a trick dont fall for it! No such thing!

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Prophase II

• (Rest is same as Mitosis)
• Sister chromatids/ Homologous pairs attach to
  spindle apparatus

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Metaphase II

• Sister chromatids/ Homologous pairs line up in
  center of the cell

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Anaphase II

• Sister chromatids/ Homologous pairs separate and
  Chromasomes/ Chromatids move to poles

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Telophase II (Cytokenesis)

• Chromosomes dissolve into chromatin
• 4 daughter cells, each with ½ original of
  chromosomes

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Meiosis video
http//www.youtube.com/watch?vkVMb4Js99tA
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Summary (yet again)

• Mitosis 1 cell forms 2 exact copies
• Asexual reproduction cloning
• Growth, maintenance, repair
• Mutations lead to uncontrolled cell growth
  cancer

• Meiosis- 1 cell forms 4 daughter cells, each with
  ½ the original of chromosomes
• Sexual reproduction
• Gamete production (sperm, egg)
• Mutations lead to dead offspring of changes in
  gene frequency (evolution)

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Advice

• Follow up on youtube
• mitosis vs. meiosis videos there are several
  good ones.

http//www.youtube.com/watch?v_llXzrz8oOc