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  1. Genetic Variation LHS Biology B

  2. Sexual and Asexual Reproduction • Organisms produce offspring in 2 different ways • Sexual reproduction requires 2 parents • Asexual reproduction only requires 1 parent • Most organisms use one or the other, but some can do both

  3. Sexual Reproduction • 2 parents’ genes combine to form a genetically unique offspring • Genetic variation comes from mutation, meiosis, and random fertilization • Usually takes more energy than asexual reproduction • Most organisms that you are most familiar with use sexual reproduction • Mammals, reptiles, birds, fish, amphibians, and many plants

  4. Asexual Reproduction • 1 parent produces a genetic copy of itself • Genetic Variation comes from mutation only • Usually takes less energy and time than sexual reproduction • Some organisms that can use asexual reproduction are: bacteria, some plants, sea stars, and hydra

  5. Summary Sexual Reproduction Asexual Reproduction • Disadvantages: • Slower • Takes more energy • More complicated • Rare organisms • Major Advantage • Genetic Variation • Disadvantage: • Little genetic variation • Advantages: • Faster • Saves Energy • Less Complicated • Only 1 parent required

  6. What type of reproduction? http://www.youtube.com/watch?v=4JIytOL-Q18 http://www.youtube.com/watch?v=gEwzDydciWc http://www.youtube.com/watch?v=5HMp-GXjHtg

  7. A type of cell division that produces reproductive cells • The cells produced are haploid, but come from a diploid parent cell • Diploid: A cell with 2 sets of chromosomes, one from each parent • Haploid: A cell with only one set of chromosomes Meiosis

  8. http://vcell.ndsu.edu/animations/meiosis/movie-flash.htm

  9. Meiosis

  10. Results of Meiosis • Produces 4 haploid cells called gametes • Reproductive cells, sperm, egg • 2 gametes (1 sperm and 1 egg) come together at fertilization, resulting in a zygote • This keeps the chromosome number from changing each generation

  11. Meiosis is different from Mitosis • 2 Divisions: Meiosis I and Meiosis II • Daughter cells are genetically unique • Different from each other and the original cell • Only occurs in certain organs of sexually reproducing organisms

  12. Challenge Question #1 • Is Meiosis happening in your body right now? • Is Mitosis happening in your body right now? • Explain :)

  13. How to Keep them Straight • MiTOsis happens in TOES • Produces identical body cells • MeIosis is why I am unique, why I am ME • Produces unique gametes

  14. Chromosomes Review

  15. Meiosis I • Pairs of chromosomes are divided • One chromosome from each pair goes to each daughter cell • Produces cells with the haploid number of chromosomes • Each daughter cell gets one chromosome from each pair • The pairs split up randomly

  16. Meiosis II • Basically like mitosis • Chromotidsseperate at the centromere like mitosis • Results in 4 haploid daughter cells • 4 functional sperm • 1 functional egg and 3 nonfunctional haploid cells (called polar bodies)

  17. Challenge Question #2 • Explain the purpose of Meiosis in just a few sentences.

  18. Fertilization • Joining of egg and sperm to produce a zygote • Zygote is a diploid cell • Random Fertilization • Any sperm is equally likely to fertilize any egg • Another source of genetic variation

  19. Challenge Question #3 • Draw and label a picture that models the process of meiosis.

  20. Discovery of DNA • DNA is the genetic material that makes up chromosomes • When it is not condensed it is called chromatin • It wasn’t that long ago that we didn’t know about DNA • See timeline on page 292 • World War II lasted from 1939 to 1949 for reference

  21. Image Credits • Bruce the shark: http://sloblogs.thetribunenews.com/sidetracked/files/2009/04/brucetheshark.jpg • Sven the Reindeer: http://static2.wikia.nocookie.net/__cb20131110022746/disney/images/8/83/SVEN2.png • Aphie and the Queen: http://images1.wikia.nocookie.net/__cb20110429014022/disney/images/e/eb/Queenbugslife.png • Bacteria: http://www.bacteriamicroscopes.com/ • Strawberry plant: http://strawberry.ifas.ufl.edu/daughter%20removal.htm • Hydra: http://www.microscope-microscope.org/gallery/Mark-Simmons/pages/hydra2.htm • Sea Star: http://www.factzoo.com/invertebrates/starfish-sea-star-armed-sea-critter.html

  22. Image Credits Continued • Meiosis Diagram 1: http://drugline.org/img/term/meiosis-9348_3.jpg • Mitosis & Meiosis side by side: http://www2.le.ac.uk/departments/genetics/vgec/highereducation/topics/cellcycle-mitosis-meiosis • Chromosomes: http://home.comcast.net/~clupold96/notes%20pages/chromosomes_tips.htm • Meiosis I: http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20101/bio%20101%20lectures/meiosis/meiosis.htm • Meiosis II: http://3.bp.blogspot.com/-czi5F0idF74/UFySnBEmB5I/AAAAAAAAAXM/MjWg4VsX34I/s640/Meiosis+II.jpg • Telophase II/Cytokinesis: https://smartsite.ucdavis.edu/access/content/user/00002950/bis10v/week4/4webimages/figure-09-14-11-photo.jpg • Anaphase II: https://smartsite.ucdavis.edu/access/content/user/00002950/bis10v/week4/4webimages/figure-09-14-9-photo.jpg • Fertilization: http://www.studyblue.com/notes/note/n/genetics/deck/5461653