2. MEIOSIS 11-4 Making gametes… http://waynesword.palomar.edu/lmexer2a.htm

3. Warm ups – February 24 th, 2012 Why don’t you look like your brothers and/or sisters? If we have 46 chromosomes in our cells, why don’t our children have 92?

4. 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 ? Interest Grabber 46 chromosomes 46 + 46 = 92; a developing embryo would not survive if it contained 92 chromosomes. Sperm and egg should each have 23 chromosomes.

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

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

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

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

9. 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

10. How about the rest of us? What if a complex multicellular organism (like us) wants to reproduce? –joining of egg + sperm Do we make egg & sperm by mitosis? 46 + 92 eggspermzygote What if we did, then…. Doesn’t work! No! 

11. ADVANTAGES OF SEXUAL REPRODUCTION Allows for variation in population Individuals can be different Provides foundation for biological change Allow species adapt to changes in their environment http://naturalsciences.sdsu.edu/classes/lab8/spindex.html

12. Human female karyotype 46 chromosomes 23 pairs XX diploid = 2 copies 2n

13. 46 chromosomes 23 pairs XY Human male karyotype diploid = 2 copies 2n

14. EGG + SPERM  If egg and sperm had same number of chromosomes as other body cells... baby would have too many chromosomes! http://www.angelbabygifts.com/ Image by Riedell http://www.acmecompany.com/stock_thumbnails/13217.forty-six_chromosomes.jpg 23 chromosomes 23 chromosomes 46 chromosomes

15. gametes How do we make sperm & eggs? Must reduce 46 chromosomes  23 –must half the number of chromosomes –haploid 23 46 egg sperm 46 meiosis 46 fertilization 23 zygote

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

17. DIPLOID & HAPLOID Most cells have 2 copies of each chromosome = ______________ (one from mom; one from dad) All BODY (___________) cells are diploid DIPLOID2n HOMOLOGOUS CHROMOSOMES = SOMATIC

18. DIPLOID & HAPLOID Some cells have only one copy of each chromosome = _____________ All sperm and egg cells are haploid HAPLOID1n

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

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

21. POLAR BODIES Produces: 1 “good” egg 3 CYTOPLASM DIVIDES UNEVENLY __________________ = MAKING a MATURE EGG OOGENESIS

22. Sperm donates mostly DNA http://bestweekever.blogs.com/photos/uncategorized/imagemain_sperm_egg1_1.gif WHY MAKE ONLY ONE “GOOD” EGG? Most of the cell parts and nutrients needed for baby come from EGG!

23. “Self digest” Using ________________ POLAR BODIES DEGENERATE (DIE) LYSOSOMES = __________________ “cell suicide” for good of organism APOPTOSIS

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

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

26. How is MEIOSIS DIFFERENT ? 1.SYNAPSIS & CROSSING OVER mom and dad’s chromosomes do a little dance and actually SWAP DNA! 2.SEGREGATION & INDEPENDENT ASSORTMENT Sperm and egg cells is a RANDOM MIX of mom and dad’s chromsomes, like a lottery drawing. 3. Skip INTERPHASE II (NO S) CELL DIVIDES TWICE, BUT… ONLY COPIES DNA ONCE

27. Let’s watch a video to see this in action

28. WHAT happens first? 1.Homologous chromosomes pair up during ________________ = ______________ SYNAPSIS Images modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif This group of FOUR (4) chromatids is called a _________________ TETRAD PROPHASE I

29. Mom and dad’s chromosomes do a little dance 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

30. 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) http://sps.k12.ar.us/massengale/genetics%20tutorial.htm NOT IDENTICAL MomDad

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

32. How are our sex cells a random mix of mom and dad’s DNA? 2. Separation during ANAPHASE I INDEPENDENT ASSORTMENT Separates gene choices and allows shuffling of genetic material SEGREGATION &

33. SEGREGATION (Anaphase I)

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

35. 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!

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

37. 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 different GENETIC RECOMBINATION

38. WHAT MAKES MEIOSIS DIFFERENT ? 3. Skip INTERPHASE II (No S) CELL DIVIDES TWICE, BUT … ONLY COPIES ITS DNA ONCE G1G1 G2G2 S   PM  A T C G1G1    MITOSIS: MEIOSIS:    SG2G2 PM ATC PM A TC ( I ) ( II )

39. Go to Section: Meiosis I Section 11-4 Figure 11-15 Meiosis

40. Go to Section: Meiosis I Section 11-4 Figure 11-15 Meiosis Meiosis I

41. Go to Section: Meiosis I Section 11-4 Figure 11-15 Meiosis Meiosis I

42. Go to Section: Section 11-4 Figure 11-15 Meiosis Meiosis I

43. Go to Section: Section 11-4 Figure 11-15 Meiosis Meiosis I

44. Go to Section: Meiosis II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. Prophase IIMetaphase IIAnaphase IITelophase II 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. Section 11-4 Figure 11-17 Meiosis II

45. Go to Section: Meiosis II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. Prophase IIMetaphase IIAnaphase IITelophase II 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. Section 11-4 Figure 11-17 Meiosis II

46. Go to Section: Meiosis II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. Prophase IIMetaphase IIAnaphase IITelophase II 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. Section 11-4 Figure 11-17 Meiosis II

47. Go to Section: Meiosis II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. Prophase IIMetaphase IIAnaphase IITelophase II 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. Section 11-4 Figure 11-17 Meiosis II

48. Go to Section: Meiosis II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. Prophase IIMetaphase IIAnaphase IITelophase II 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. Section 11-4 Figure 11-17 Meiosis II

49. 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

50. Activity Draw out the steps of Meiosis using 3 PAIRS of homologous chromosomes This means you should choose 6 COLORS to represent each chromosome Use contrasting colors for homologous chromosomes to show crossing over (Go back to animation for example)

51. MAKING SPERM & EGGS