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MEIOSIS 11-4. http://waynesword.palomar.edu/lmexer2a.htm. Making gametes…. Interest Grabber. 1. How many chromosomes would a sperm or an egg contain if either one resulted from the process of mitosis?
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MEIOSIS11-4 http://waynesword.palomar.edu/lmexer2a.htm Making gametes…
Interest Grabber 1. How many chromosomes would a sperm or an egg contain if either one resulted from the process of mitosis? 2. If a sperm containing 46 chromosomes fused with an egg containing 46 chromosomes, how many chromosomes would the resulting fertilized egg contain? Do you think this would create any problems in the developing embryo? 3. In order to produce a fertilized egg with the appropriate number of chromosomes (46), how many chromosomes should each sperm and egg have? 46 chromosomes 46 + 46 = 92; a developing embryo would not survive if it contained 92 chromosomes. Sperm and egg should each have 23 chromosomes.
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
ADVANTAGES and DISADVANTAGES OF ASEXUAL REPRODUCTION Advantages: • Can make offspring faster • Don’t need a partner Disadvantages: • ALL ALIKE • Species CAN’T change and adapt • One disease can wipe out whole population http://www.mrgrow.com/images/cutting.jpg
SEXUAL REPRODUCTION Family image from: http://babyhearing.org/Parenet2Parent/index.asp Combines genetic material from 2 parents (sperm & egg) so offspring are genetically __________ from parents DIFFERENT
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
MEIOSIS is the way… to make cells with ½ the number of chromosomes for sexual reproduction http://waynesword.palomar.edu/lmexer2a.htm
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
DIPLOID & HAPLOID HAPLOID 1n Some cells have only one copy of each chromosome = _____________ All sperm and egg cells are haploid
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
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
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
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
WHAT MAKES MEIOSIS DIFFERENT? CROSSING OVER 1. Exchange of DNA betweenhomologous pairs = _____________during PROPHASE I Allows shuffling of genetic material http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
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
WHAT MAKES MEIOSIS DIFFERENT ? 2.Separation during ANAPHASE I SEGREGATION & INDEPENDENT ASSORTMENT Separates gene choices and allows shuffling of genetic material
INDEPENDENT ASSORTMENT http://fig.cox.miami.edu/~cmallery/150/mitosis/c13x9independent-assortment.jpg
WHAT MAKES MEIOSIS DIFFERENT ? Crossing over Segregation Independent assortment are ALL ways MEIOSIS results in =______________________________ So daughter cells are ______________ from parents and from each other GENETIC RECOMBINATION different
WHAT MAKES MEIOSIS DIFFERENT ? 3. Skip INTERPHASE II (No S) CELL DIVIDES TWICE, BUT … ONLY COPIES ITS DNA ONCE MITOSIS: P M A C G1 T S G2 MEIOSIS: ( I ) G1 A T C S G2 P M ( II ) A P M T C
Figure 11-15 Meiosis Section 11-4 Meiosis I
Figure 11-15 Meiosis Section 11-4 Meiosis I Meiosis I
Figure 11-15 Meiosis Section 11-4 Meiosis I Meiosis I
Figure 11-15 Meiosis Section 11-4 Meiosis I
Figure 11-15 Meiosis Section 11-4 Meiosis I
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.
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.
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.
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.
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.
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
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
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
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
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
MITOSIS vs MEIOSIS CYTOKINESIS CYTOKINESIS I http://www.pbs.org/wgbh/nova/baby/divi_flash.html Cytoplasm splits into 2 cells SAME AS MITOSIS
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
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
MITOSIS vs MEIOSIS METAPHASE METAPHASE II http://www.pbs.org/wgbh/nova/baby/divi_flash.html • Chromosomes line up in middle SAME AS MITOSIS
MITOSIS vs MEIOSIS ANAPHASE ANAPHASE II http://www.pbs.org/wgbh/nova/baby/divi_flash.html Chromatids split and move apart SAME AS MITOSIS
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
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
SPERMATOGENESIS ___________________= MAKING MATURE SPERM
Sperm provides DNA All the starting nutrients, organelles, molecule building blocks, etc. have to come from the egg.
OOGENESIS __________________ = MAKING a MATURE EGG Produces: 1 “good” egg 3 POLAR BODIES CYTOPLASM DIVIDES UNEVENLY
WHY MAKE ONLY ONE “GOOD” EGG? Sperm donates mostly DNA Most of the cell parts and nutrients needed for baby come from EGG! http://bestweekever.blogs.com/photos/uncategorized/imagemain_sperm_egg1_1.gif
“Self digest” Using ________________ POLAR BODIES DEGENERATE (DIE) LYSOSOMES APOPTOSIS = __________________ “cell suicide” for good of organism