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MEIOSIS Genetics

MEIOSIS Genetics. Slide show modified from Kelly Riedell, Tracy Jackson and Kim Foglia. BINARY FISSION & MITOSIS. identical. Produces cells that are genetically __________ copies of parent cell. Parent. Bud. 0.5 mm. Asexual vs. Sexual Reproduction. In asexual reproduction

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MEIOSIS Genetics

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  1. MEIOSISGenetics Slide show modified from Kelly Riedell, Tracy Jackson and Kim Foglia

  2. BINARY FISSION & MITOSIS identical Produces cells that are genetically __________ copies of parent cell

  3. Parent Bud 0.5 mm Asexual vs. Sexual Reproduction • In asexual reproduction • One parent produces genetically identical offspring by mitosis • Ex: budding, binary fission, spores, etc.

  4. ADVANTAGES OF ASEXUAL REPRODUCTION • Can make offspring faster • Don’t need a partner; only 1 “parent” needed

  5. DISVANTAGES OF ASEXUAL REPRODUCTION • ALL ALIKE (“clones”) • Species usually CAN’T change and adapt • One disease can wipe out whole population

  6. SEXUAL REPRODUCTION • Combines genetic material from 2 parents (sperm & egg) • Offspring are genetically different and unique from parents

  7. ADVANTAGES OF SEXUAL REPRODUCTION • Allows for variation in population • Individuals can be different • Provides foundation for EVOLUTION • Allow species adapt to changes in their environment

  8. EGG +  SPERM If egg and sperm had same number of chromosomes as other body cells (2n) . . . baby would have too many chromosomes!

  9. MEIOSIS is the way… to make cells with ½ the number of chromosomes for sexual reproduction http://waynesword.palomar.edu/lmexer2a.htm

  10. DIPLOID DIPLOID 2n Most cells have 2 copies of each chromosome = ______________ (one from mom; one from dad) All BODY (________ ) cells are diploid HOMOLOGOUSCHROMOSOMES SOMATIC

  11. Chromosomes that determine the sex of an organism = _________________ All other chromosomes that do NOT determine gender = __________ Sex chromosomes autosomes Humans have two sex chromosomes (1 pair), which are NOT homologous and _____ autosomes XX or XY 44

  12. HAPLOID HAPLOID 1n Some cells have only one copy of each chromosome = _____________ All sperm and egg cells are haploid

  13. Review…MITOSIS 2 identical • Makes ___ cells genetically _________ to parent cell & to each other • Makes ___ cells • Makes __________ • Used by organisms to: increase size of organism, repair injuries, replace worn out cells 2n SOMATIC (body) http://waynesword.palomar.edu/lmexer2a.htm

  14. MEIOSIS 4 • Makes ____ cells genetically different from parent cell & from each other • Makes _____ cells • Makes ______________ • Used for ____________ 1n Gametes (sperm & eggs) Sexual reproduction http://waynesword.palomar.edu/lmexer2a.htm

  15. 2 karyokinesis events occur in meiosis!

  16. WHAT MAKES MEIOSIS DIFFERENT FROM MITOSIS ? • 2 divisions instead of 1 • Meiosis I and Meiosis II(PMATc I & PMATc II) • SYNAPSIS & CROSSING OVER (PROPHASE I) • INDEPENDENT ASSORTMENT and SEGREGATION (ANAPHASE I) • 4 cells are made and they are haploid • Daughter cells are genetically DIFFERENT

  17. WHAT MAKES MEIOSIS DIFFERENT FROM MITOSIS? • Homologous chromosomes pair up during ________________ = PROPHASE I called SYNAPSIS (Pairing of two homologous chromosomes) This group of FOUR (4) chromatids is called a _________________ TETRAD Images modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif

  18. WHAT MAKES MEIOSIS DIFFERENT FROM MITOSIS? CROSSING OVER 1. Exchange of DNA betweenhomologous pairs = _____________during PROPHASE I Allows shuffling of genetic material called genetic recombination Place(s) where crossing over happens = ____________________ CHIASMATA http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter12/animations.html#

  19. CROSSING OVER • Allows for_________________ in different combinations • After crossing over, chromatid arms are________________ anymore rearranging of DNA NOT IDENTICAL http://sps.k12.ar.us/massengale/genetics%20tutorial.htm

  20. INDEPENDENT ASSORTMENTthe random alignment of homolgous chromosome pairs at metaphase plate (Metaphase I) http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120074/bio18.swf::Random%20Orientation%20of%20Chromosomes%20During%20Meiosis

  21. Random Orientation of Chromosomes During Meiosis http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120074/bio18.swf::Random%20Orientation%20of%20Chromosomes%20During%20Meiosi

  22. SEGREGATIONseparating of homologous pairs (Anaphase I)

  23. SEGREGATION & CROSSING OVERtogether make even more gamete combinations http://waynesword.palomar.edu/lmexer2a.htm

  24. INDEPENDENT ASSORTMENT and SEGREGATIONat METAPHASE/ANAPHASE I Lots of different combinations are possible! This is why you don’t look exactly like your brothers and sisters even though you share the same parents! 3rd animation http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter12/animations.html#

  25. GENETIC RECOMBINATIONcomes from: • Crossing over • Segregation • Independent assortment • Random fertilization

  26. PHASES OF MEIOSIS Figure 11-15 Meiosis Section 11-4 Meiosis I = MAJOR differences from mitosis

  27. Meiosis II: NOTE- no Interphase II- instead short intermission (no growth or DNA replication occurs) Figure 11-17 Meiosis II Section 11-4 Prophase II Metaphase II Anaphase II Telophase II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. The chromosomes line up in a similar way to the metaphase stage of mitosis. The sister chromatids separate and move toward opposite ends of the cell. Meiosis II results in four haploid (N) daughter cells.

  28. Stages of Meiosis • http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120074/bio19.swf::Stages%20of%20Meiosis

  29. MITOSIS vs. MEIOSISINTERPHASE INTERPHASE I http://www.pbs.org/wgbh/nova/baby/divi_flash.html 2n cell 2n cell • DNA is spread out as chromatin • Nuclear membrane/nucleolus visible • DNA is copied during S phase • Makes stuff new cell needs in G2 • Cell Grows SAME AS MITOSIS

  30. MITOSIS vs. MEIOSIS PROPHASE PROPHASE I 2n cell 2n cell • DNA packs into chromosomes • Nuclear membrane/ nucleolus disappear • Spindle fibers appear and attach to chromosomes • Centrosomes migrate to poles • DNA packs into chromosomes • Nuclear membrane/ nucleolus disappear • Spindle fibers appear and attach to chromosomes • Centrosomes migrate to poles SYNAPSIS and CROSSING OVER OCCURS

  31. MITOSIS vs. MEIOSIS METAPHASE METAPHASE I 2n cell 2n cell • Chromosomes line up in middle in single file line • Chromosomes line up in middle with • homologous partner • Independent assortment occurs

  32. MITOSIS vs. MEIOSIS ANAPHASE ANAPHASE I 2n cell 2n cell • Polar fibers lengthen cell • Chromatids split • Polar fibers lengthen cell • Chromatids stay togetherHomologous pairs split (SEGREATION OCCURS)

  33. MITOSIS vs. MEIOSIS TELOPHASE TELOPHASE I • See TWO nuclei • Nuclear membrane/ nucleolus return • DNA spreads out as chromatin • Spindle fibers disappear 2n cell n cell SAME AS MITOSIS

  34. MITOSIS vs. MEIOSIS CYTOKINESIS CYTOKINESIS I 2n cell n cell Cytoplasm splits into 2 cells using DIPLOID HAPLOID SAME AS MITOSIS

  35. MITOSIS vs. MEIOSIS INTERPHASE II 2n cell n cell • DNA is spread out as chromatin • Nuclear membrane/nucleolus visible • DNA is copied during S phase • Makes stuff new cell needs in G2 • Cell Grows SKIP INTERPHASE II DNA NOT COPIED

  36. MITOSIS vs. MEIOSIS PROPHASE PROPHASE II n cell 2n cell • DNA packs into chromosomes • Nuclear membrane/ nucleolus disappear • Spindle fibers appear and attach to chromosomes • Centrosomes migrate to poles SAME AS MITOSIS (but cell is now HAPLOID)

  37. MITOSIS vs. MEIOSIS METAPHASE METAPHASE II n cell 2n cell • Chromosomes line up in middle in a single file line SAME AS MITOSIS (but cell is now HAPLOID)

  38. MITOSIS vs. MEIOSIS ANAPHASE ANAPHASE II 2n cell n cell Chromatids split and move apart SAME AS MITOSIS (but cell is now HAPLOID)

  39. MITOSIS vs. MEIOSIS TELOPHASE TELOPHASE II 2n cell n cell • See TWO nuclei • Nuclear membrane/ nucleolus return • DNA spreads out as chromatin • Spindle fibers disappear SAME AS MITOSIS (but cell is now HAPLOID)

  40. MITOSIS vs. MEIOSIS CYTOKINESIS CYTOKINESIS II Cytoplasm splits RESULTS IN FOUR n cell RESULTS IN TWO 2n cell SAME AS MITOSIS (but cell is now HAPLOID) http://www.pbs.org/wgbh/nova/baby/divi_flash.html

  41. Ways Meiosis is different? Unique Features of Meiosis: http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120074/bio16.swf::Unique%20Features%20of%20Meiosis Mitosis vs. Meiosis: http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120074/bio17.swf::Comparison%20of%20Meiosis%20and%20Mitosis

  42. MAKING SPERM & EGGS

  43. Gametogenesis = • process of forming gametes (n) from diploid (2n) cells 2 TYPES: • Spermatogenesis = process of forming sperm cells • After division all 4 cells undergo differentiation to become sperm cells • The cells elongate and grow tail (a flagella) • Oogenesis = process of forming ovum (egg) cell and 3 polar bodies

  44. Starts with a 2n cell called a GERM LINE CELL

  45. SPERMATOGENESIS ___________________= MAKING MATURE SPERM Mature & grow flagella

  46. Spermatogenesis • https://www.youtube.com/watch?v=6fBa8UqEano

  47. Sperm provides DNA to the zygote. • All the starting nutrients, organelles, molecule building blocks, etc. have to come from the ovum (egg)

  48. OOGENESIS __________________ = MAKING a MATURE EGG Produces: 1 “good” ovum (egg) 3 POLAR BODIES • CYTOPLASM DIVIDES UNEVENLY • Polar bodies are smaller and are later destroyed using APOPTOSIS

  49. Oogenesis • https://www.youtube.com/watch?v=kjOOAaze-Ng

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