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Mitosis vs. Meiosis No sex vs. Sex

Mitosis vs. Meiosis No sex vs. Sex. Which is better? Mr. Snider SOCES socesbio.com. Why do Mitosis?. Growth 1 cell to billions exponentially Maintenance – replace skin, stomach Repair- injuries. Why do Meiosis?. Variation – not FUN

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Mitosis vs. Meiosis No sex vs. Sex

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  1. Mitosis vs. Meiosis No sex vs. Sex Which is better? Mr. Snider SOCESsocesbio.com

  2. Why do Mitosis? • Growth 1 cell to billions exponentially • Maintenance – replace skin, stomach • Repair- injuries

  3. Why do Meiosis? • Variation – not FUN • Remember over 50% of sexual reproduction does not include intercourse

  4. 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 Mitosis vs. Meiosis

  5. Quick video comparison http://www.youtube.com/watch?v=Ba9LXKH2ztU

  6. Physical structure vs. genetics • Physically Meiosis and Mitosis are similar • IPMAT • Interphase • Prophase • Metaphase • Anaphase • Telophase (Cytokenesis)

  7. Mitosis preview – bear with 5 mins • Awesome video http://www.youtube.com/watch?v=Q6ucKWIIFmg

  8. 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)

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

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

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

  12. 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

  13. 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)

  14. Review Mitosis http://www.youtube.com/watch?v=kRWnJd1WRbA

  15. 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?

  16. Meiosis • Diploid cell to haploid gamete • Diploid = 2 copies of chromosomes(2N) • Haploid = 1 copy (N or 1N) • If you add 2N+2N 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)

  17. Interphase • Same as in Mitosis – DNA and organelles double (DNA during S phase)

  18. 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

  19. Metaphase I • Tetrads line up in center of cell

  20. 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

  21. Telophase I • Homologous pairs/ Sister Chromatids sometimes uncondense (most don’t- loss of Energy)

  22. Interphase II • It’s a trick – don’t fall for it! No such thing!

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

  24. Metaphase II • Sister chromatids/ Homologous pairs line up in center of the cell

  25. Anaphase II • Sister chromatids/ Homologous pairs separate and Chromasomes/ Chromatids move to poles

  26. Telophase II (+Cytokenesis) • Chromosomes dissolve into chromatin • 4 daughter cells, each with ½ original # of chromosomes

  27. Meiosis video http://www.youtube.com/watch?v=kVMb4Js99tA

  28. 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) Summary (yet again)

  29. Advice • Follow up on youtube – mitosis vs. meiosis videos; there are several good ones. http://www.youtube.com/watch?v=_llXzrz8oOc

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