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MEIOSIS Chapter 13

Explore the intricate process of meiosis, essential for sexual reproduction and genetic variation. Learn about haploid and diploid cells, crossing over, and genetic recombination. Understand the advantages and disadvantages of asexual and sexual reproduction in living organisms.

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MEIOSIS Chapter 13

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  1. MEIOSISChapter 13 Slide show modified from Tracy Jackson and Kim Foglia http://waynesword.palomar.edu/lmexer2a.htm

  2. Remember from Chapter 1:CHARACTERISTICS OF LIVING THINGSALL LIVING THINGS __________ REPRODUCE ASEXUAL SEXUAL Planaria animation: http://www.t3.rim.or.jp/~hylas/planaria/title.htmFamily http://babyhearing.org/Parenet2Parent/index.asp

  3. ASEXUAL REPRODUCTION http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmito.html BINARY FISSION Bacteria reproduce using __________________________________ Budding & regeneration are used by plants and animals to reproduce asexually (mitosis) http://fig.cox.miami.edu/~cmallery/150/mitosis/c7.13.2.hydra.jpg Planaria animation: http://www.t3.rim.or.jp/~hylas/planaria/title.htm

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

  5. ADVANTAGES OF ASEXUAL REPRODUCTION Can make offspring faster Don’t need a partner http://www.mrgrow.com/images/cutting.jpg

  6. DISVANTAGES OF ASEXUAL REPRODUCTION ALL ALIKE Species CAN’T change and adapt One disease can wipe out whole population http://www.mrgrow.com/images/cutting.jpg

  7. SEXUAL REPRODUCTION Family image from: http://babyhearing.org/Parenet2Parent/index.asp Combines genetic material from 2 parents (sperm & egg) Offspring are genetically different from parents

  8. 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 http://naturalsciences.sdsu.edu/classes/lab8/spindex.html

  9. http://www.angelbabygifts.com/ Image by Riedell Image by Riedell EGG +  SPERM If egg and sperm had same number of chromosomes as other body cells . . . baby would have too many chromosomes! http://www.acmecompany.com/stock_thumbnails/13217.forty-six_chromosomes.jpg

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

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

  12. Chromosomes that determine the sex of an organism = _________________ All other chromosomes = _________________ http://www.angelbabygifts.com/ Sex chromosomes autosomes Humans have two sex chromosomes and _____ autosomes y X 44

  13. KARYOTYPE A __________ is a picture of an organism’s chromosomes

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

  15. 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

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

  17. WHAT MAKES MEIOSIS DIFFERENT ? • SYNAPSIS & CROSSING OVER (PROPHASE I) • SEGREGATION & INDEPENDENT ASSORTMENT (ANAPHASE I) 3. Skip INTERPHASE II (NO S) CELL DIVIDES TWICE, BUT… ONLY COPIES DNA ONCE

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

  19. WHAT MAKES MEIOSIS DIFFERENT? CROSSING OVER 1. Exchange of DNA betweenhomologous pairs = _____________during PROPHASE I Allows shuffling of genetic material Places where crossing over happens = ____________________ CHIASMATA http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif

  20. HOMOLOGOUS CHROMOSOMES Image modified by Riedell • SAME SIZE • SAME SHAPE • CARRY GENES for the SAME TRAITS • BUT ______________! (Don’t have to have the SAME CHOICES) NOT IDENTICAL http://sps.k12.ar.us/massengale/genetics%20tutorial.htm

  21. Image modified by Riedell 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

  22. SEGREGATION(Anaphase I)

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

  24. INDEPENDENT ASSORTMENT http://fig.cox.miami.edu/~cmallery/150/mitosis/c13x9independent-assortment.jpg

  25. INDEPENDENT ASSORTMENTat 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!

  26. http://www.tokyo-med.ac.jp/genet/anm/mimov.gi

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

  28. Figure 11-15 Meiosis Section 11-4 Meiosis I

  29. Figure 11-17 Meiosis II Section 11-4 Meiosis II 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.

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

  31. MITOSIS vs MEIOSIS PROPHASE PROPHASE I http://www.pbs.org/wgbh/nova/baby/divi_flash.html DNA scrunches into chromosomes Nuclear membrane/ nucleolus disappear Centrioles/spindle fibers appear DNA scrunches into chromosomesNuclear membrane/ nucleolus disappear Centrioles/ spindle fibers appear Homologous pairs match up

  32. MITOSIS vs MEIOSIS METAPHASE METAPHASE I http://www.pbs.org/wgbh/nova/baby/divi_flash.html • Chromosomes line up in middle Chromosomes line up in middle with homologous partner

  33. MITOSIS vs MEIOSIS ANAPHASE ANAPHASE I http://www.pbs.org/wgbh/nova/baby/divi_flash.html APART: Chromatids split APART: Chromatids stay togetherHomologous pairs split

  34. MITOSIS vs MEIOSIS TELOPHASE TELOPHASE I http://www.pbs.org/wgbh/nova/baby/divi_flash.html See TWO nuclei Nuclear membrane/ nucleolus return DNA spreads out as chromatin Spindle/centrioles disappear SAME AS MITOSIS

  35. MITOSIS vs MEIOSIS CYTOKINESIS CYTOKINESIS I http://www.pbs.org/wgbh/nova/baby/divi_flash.html Cytoplasm splits into 2 cells SAME AS MITOSIS

  36. MITOSIS vs MEIOSIS INTERPHASE II http://www.pbs.org/wgbh/nova/baby/divi_flash.html • DNA is spread out as chromatin • Nuclear membrane/ nucleolus visible • DNA is copied during S phase SKIP INTERPHASE II DNA NOT COPIED

  37. MITOSIS vs MEIOSIS PROPHASE PROPHASE II http://www.pbs.org/wgbh/nova/baby/divi_flash.html • DNA scrunches into chromosomes • Nuclear membrane/nucleolus disappear • Centrioles/ spindle fibers appear SAME AS MITOSIS

  38. MITOSIS vs MEIOSIS METAPHASE METAPHASE II http://www.pbs.org/wgbh/nova/baby/divi_flash.html • Chromosomes line up in middle SAME AS MITOSIS

  39. MITOSIS vs MEIOSIS ANAPHASE ANAPHASE II http://www.pbs.org/wgbh/nova/baby/divi_flash.html Chromatids split and move apart SAME AS MITOSIS

  40. MITOSIS vs MEIOSIS TELOPHASE TELOPHASE II http://www.pbs.org/wgbh/nova/baby/divi_flash.html Two nuclei Nuclear membrane/nucleolus returns Centrioles/spindle fibersdisappear DNA spreads out as chromatin SAME AS MITOSIS

  41. MITOSIS vs MEIOSIS CYTOKINESIS CYTOKINESIS II http://www.pbs.org/wgbh/nova/baby/divi_flash.html Cytoplasm splits SAME AS MITOSIS http://www.pbs.org/wgbh/nova/baby/divi_flash.html

  42. Ways Meiosis is different? • Homologous pairs match up & trade DNA (SYNAPSIS & CROSSING OVER) in PROPHASE I • SEGREGATION • & INDEPENDENT ASSORTMENT in Anaphase I • create genetic recombination • Skipping INTERPHASE II- • (Dividing TWICE but copying DNA once) • produces 1ncells

  43. MAKING SPERM & EGGS

  44. Gametogenesis = process of forming gametes (n) from diploid (2n) cells Spermatogenesis = process of forming sperm cells by meiosis in animals, by mitosis in plants in specialized organs After division all 4 cells undergo differentiation to become sperm cells

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

  46. Sperm provides DNA All the starting nutrients, organelles, molecule building blocks, etc. have to come from the egg. http://www.moondragon.org/obgyn/pregnancy/twins.html

  47. OOGENESIS __________________ = MAKING a MATURE EGG Produces: 1 “good” egg 3 POLAR BODIES CYTOPLASM DIVIDES UNEVENLY http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory/files/Bio%20102/Bio%20102%20lectures/Animal%20Reproduction/animal.htm

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