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

DO NOW What are three differences between mitosis and meiosis? HOMEWORK: Watch Bozeman Sordaria Cross Video; take notes

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

ASEXUAL REPRODUCTION Bacteria reproduce using BINARY FISSION http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmito.html Bacteria reproduce using __________________________________ Budding & regeneration are used by plants and animals to reproduce asexually (mitosis) BINARY FISSION 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

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

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

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

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

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

+ EGG SPERM  If egg and sperm had same number of 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

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

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

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 X y 44

A __________ is a picture of an organism’s chromosomes KARYOTYPE 14

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

MITOSIS 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 2 identical 2n SOMATIC (body) http://waynesword.palomar.edu/lmexer2a.htm

MEIOSIS 4 1n Germ cells OR Gametes (sperm & eggs) sexual reproduction 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

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? 1. Exchange of DNA between homologous pairs = _____________ during PROPHASE I CROSSING OVER Allows shuffling of genetic material Places where crossing over happens = ____________________ CHIASMATA http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif

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

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

SEGREGATION (Anaphase I)

SEGREGATION & CROSSING OVER together make even more combinations See an animation http://waynesword.palomar.edu/lmexer2a.htm

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

INDEPENDENT ASSORTMENT at 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!

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

GENETIC RECOMBINATION comes from: Crossing over Segregation Independent assortment Random fertilization

Figure 11-15 Meiosis Section 11-4 Meiosis I

Figure 11-17 Meiosis II 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.

MITOSIS vs MEIOSIS INTERPHASE 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 chromosomes Nuclear 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: APART: Chromatids split Chromatids stay together Homologous 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 fibers disappear DNA spreads out as chromatin SAME AS MITOSIS

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

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 1n cells

MAKING SPERM & EGGS

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

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

All the starting nutrients, organelles, molecule building blocks, 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

CYTOPLASM DIVIDES UNEVENLY 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

APOPTOSIS LYSOSOMES POLAR BODIES DEGENERATE (DIE) “Self digest” Using ________________ LYSOSOMES APOPTOSIS = __________________ “cell suicide” for good of organism http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory/files/Bio%20102/Bio%20102%20lectures/Animal%20Reproduction/animal.htm

Oogenesis = process of forming an ovum (egg) by meiosis in animals by mitosis in the gametophyte in plants in specialized gonads known as ovaries. Unlike spermatogenesis, cytoplasm divides unevenly so that all cytoplasm/organelles go to 1 large egg. 3 other cells = polar bodies; do not develop. Thus, all the cytoplasm and organelles go into the egg. Human males produce 200,000,000 sperm per day, while the female produces one egg (usually) each menstrual cycle.

Life Cycles A life cycle is the generation-to-generation sequence of stages in the reproductive history of an organism, from conception to production of its own offspring.

ALTERNATION OF GENERATIONS

IN PLANTS AND SOME ALGAE: ____________ = SPOROPHYTE multicellular diploid stage in which meiosis makes haploid cells called _________ Spores give rise to a multicellular HAPLOID organism = ________________ without fusing with another cell SPOROPHYTE SPORES GAMETOPHYTE Image from Biology Campbell and Reece

IN FUNGI and SOME PROTISTS: Gametes fuse to make a diploid zygote Meiosis occurs in zygote without growing into a diploid organism Meiosis makes haploid cells that grow into haploid organisms which use MITOSIS to make GAMETES! Image from Biology Campbell and Reece

Meiosis Animations Frame-by-frame animation http://www.csuchico.edu/~jbell/Biol207/animations/meiosis.html Continuous animation – no words http://www.people.virginia.edu/~rjh9u/meioanim.html Continuous frame-by-frame http://www.trentu.ca/biology/101/14.html