MEIOSIS 8-3 http://waynesword.palomar.edu/lmexer2a.htm Making gametes…

ALL LIVING THINGS Reproduce _______________ REPRODUCTION No recombination of genetic material; ONLY ONE parent Seen in bacteria and some animals Planaria animation: http://www.t3.rim.or.jp/~hylas/planaria/title.htm

CELL DIVISION in PROKARYOTES Bacteria reproduce using __________________ DNA is copied Cell splits into two new cells http://www.tnau.ac.in/notesbscag/agm/UGMicro/AGM151_201/theory_files/image156.jpg

BINARY FISSION Makes ____ cells genetically identical Used to for ___________ reproduction in bacteria http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookTOC.html

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

ALL LIVING THINGS Reproduce ____________ REPRODUCTION Combines the genetic material from 2 parents (sperm & egg) Family image from: http://babyhearing.org/Parenet2Parent/index.asp

ADVANTAGES OF SEXUAL REPRODUCTION Allows for variation in population Individuals can be different 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/ EGG + SPERM  If egg and sperm had same number of chromosomes as other body cells …. baby would have too many chromosomes!

MEIOSIS is the way… to make HAPLOID (1n) cells for sexual reproduction http://waynesword.palomar.edu/lmexer2a.htm

DIPLOID & HAPLOID (one from mom; one from dad) Some cells have 2 copies of each chromosome = _______________ (one from mom; one from dad) All BODY cells are diploid Image from: http://www.ncu.edu.tw/~ls/graph/faculty_pictures/whole_time/SLC/SLC_lab-1.jpg

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

MITOSIS Makes 2 cells genetically identical to parent cell & to each other Makes 2n cells Makes body cells Used to grow organisms, repair injuries, replace worn out cells http://waynesword.palomar.edu/lmexer2a.htm

MEIOSIS Makes ____ cells genetically different from parent cell & from each other Makes _____ cells Makes ______________ Used for ____________ http://waynesword.palomar.edu/lmexer2a.htm

WHAT MAKES MEIOSIS DIFFERENT ? SYNAPSIS & CROSSING OVER (PROPHASE I) 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 = ______________________ Images modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif

WHAT MAKES MEIOSIS DIFFERENT? Exchange of DNA between homologous pairs = ________________________ during PROPHASE I Produces daughter cells with different gene combinations http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif

HOMOLOGOUS PAIR Same size Same shape Carry genes for the same traits, but …. THEY ARE NOT IDENTICAL Can carry different gene choices Image modified from: http://arnica.csustan.edu/biol3020/cell_division/cell_division.htm

http://waynesword.palomar.edu/lmexer2a.htm

WHAT MAKES MEIOSIS DIFFERENT ? 2. Mixing up of maternal and paternal chromosomes during ANAPHASE I = ________________________________

INDEPENDENT ASSORTMENT

INDEPENDENT ASSORTMENT at ANAPHASE I Lots of different combinations are possible! This is why you don’t look exactly like your brothers and sisters.

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

WHAT MAKES MEIOSIS DIFFERENT ? ____________________________ and __________________________________ Produce daughter cells that are ___________ from the parent cells = ________________________________

WHAT MAKES MEIOSIS DIFFERENT ? Skip INTERPHASE II (No S) CELL DIVIDES TWICE, BUT … ONLY COPIES ITS DNA ONCE MITOSIS: G1 S G2 P M A T C        MEIOSIS: G1 A T C S G2 P M        P M A T C    

MITOSIS vs MEIOSIS INTERPHASE INTERPHASE I http://www.pbs.org/wgbh/nova/baby/divi_flash.html DNA spread out as chromatin Nuclear membrane/ nucleolus visible DNA copied during S phase Make stuff new cell needs 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

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

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 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 spread out as chromatin Nuclear membrane/ nucleolus visible DNA copied during S phase

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 (SYNAPSIS) in PROPHASE I CROSSING OVER (Prophase I) and INDEPENDENT ASSORTMENT (Anaphase I) create genetic recombination Skipping INTERPHASE II- (Dividing TWICE but copying DNA once) produces 1n cells

WHAT CAN GO WRONG? One pair of chromosomes fails to separate One daughter cell gets one extra chromosome is missing one chromosome http://www.tokyo-med.ac.jp/genet/anm/domov.gif

WHAT CAN GO WRONG? http://members.tripod.com/~yenial/chromosome.html

MAKING SPERM & EGGS

PRODUCTION OF MATURE SPERM = __________________________ Mature & grow flagella

Sperm provides DNA All the starting nutrients, organelles, molecule building blocks, etc. have to come from the egg.

PRODUCTION OF A MATURE EGG= __________________________ Produces: 1 “good” egg 3 POLAR BODIES CYTOPLASM DIVIDES UNEVENLY

POLAR BODIES DEGENERATE (DIE) “Self digest” Using ________________ = __________________ “cell suicide”