MEIOSIS 11-4 Making gametes… 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.

Remember from Chapter 1: CHARACTERISTICS OF LIVING THINGS ALL LIVING THINGS __________ REPRODUCE 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 DIFFERENT Combines genetic material 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

+ 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

Click the image to play the video segment 11A. Meiosis Overview Click the image to play the video segment 11A. Video 1

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

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 http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif

Click the image to play the video segment. 11E Crossing Over SEE CROSSING OVER ANIMATION Click the image to play the video segment. 11E Video 5

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

WHAT MAKES MEIOSIS DIFFERENT ? 2.Separation during ANAPHASE I SEGREGATION & INDEPENDENT ASSORTMENT Separates gene choices and allows shuffling of genetic material

Click the image to play the video segment 11D. Segregation of Chromosomes Click the image to play the video segment 11D. Video 4

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

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: G1 S G2 P M A T C        MEIOSIS: ( I ) G1 A T C S G2 P M        P M A T C ( II )    

Click the image to play the video segment 11B. & C Animal Cell Meiosis, Part 1 & Part 2 Click the image to play the video segment 11B. & 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 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.

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.

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.

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.

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.

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