Meiosis and Sexual Reproduction Chapter 7 http://www.emc.maricopa.edu/faculty/farabee/BIOBK/humanlifecyc.jpg

Chapter 7 Vocab 7. Ovum- mature egg cell. 8. Homologous 9. haploid 1. Meiosis 2. Crossing-over 3 independent assortment 4. Spermatogenesis- special cell division in males that results in 4 haploid gametes. 5. Sperm 6. oogenesis- a special type of cell division in females that results in creation of a single ovum. 7. Ovum- mature egg cell. 8. Homologous 9. haploid 10. Fertilization 11. diploid

Meiosis A. meiosis- a form of cell division that reduces the chromosome number by half, forming specialized cells (egg & sperm) http://genetics.gsk.com/graphics/meiosis-big.gif

b. The nucleus divides twice! 1. Meiosis I and Meiosis II- each goes through the following stages: A. prophase B. metaphase C. anaphase D. telophase- includes cytokinesis The result is 4 haploid cells http://www.personal.psu.edu/faculty/t/r/trp2/meiosis.jpeg

Review Questions 1. How is meiosis different from mitosis? 2. How many times does the cell divide in meiosis? 3. How many cells are made from meiosis? 4. Are the new cells haploid or diploid? 5. Where in your body does meiosis occur?

Meiosis Contributes to Genetic Variation 1. Chromosomes pairs separate independently A. independent assortment- random distribution of chromosomes during meiosis B. 23 pairs of chromosomes give 223 (about 8 million) different gamete combinations are possible http://fig.cox.miami.edu/~cmallery/150/mitosis/c13x9independent-assortment.jpg

Crossing-over and random fertilization A. Crossing-over: the exchange of DNA segments between homologous chromosomes. B. this makes genetic combinations unlimited C. fertilization of gametes is random- 64 trillion possibilities. http://regentsprep.org/Regents/biology/units/evolution/crossovr.gif

The Importance of Genetic Variation A. genetic variation is essential to evolution. B. the greater the variation the faster evolution occurs. C. evolutionary change must be favored by natural selection. http://evolution.berkeley.edu/evosite/relevance/images/refugia.gif

Review Questions 6. How are chromosome pairs separated during meiosis? 7. What is crossing-over? 8. Why is genetic variation so important?

Gamete Formation in Male and Female Animals involves Meiosis 1. Meiosis in males-spermatogenesis A. Occurs in testes B. produces four haploid sperm http://img.sparknotes.com/content/testprep/bookimgs/sat2/biology/0003/spermatogenesis.gif

Meiosis in females-Oogenesis A. occurs in ovary B. at the end of meiosis I, the cytoplasm divides unequally 1. Larger of the two cells becomes the egg. 2. Smaller cell is called a polar body C. the larger cell undergoes meiosis II which results in unequal cell division 1. The larger cell is called the ovum 2. The smaller cell is a polar body. http://www.vialattea.net/spaw/Image/biologia/oogenesis.JPG

http://jon.visick.faculty.noctrl.edu/images/Meiosis.gif

Review Questions 9. How many sperm are produced from spermatogenesis? 10. How many eggs are produced from oogenesis? 11. What is a polar body?

Types of Asexual Reproduction Budding - unequal division Ex. yeast http://archive.microbelibrary.org/microbelibrary/files/ccImages/Articleimages/Meaden/video/growth/big/growth.mov http://www.rkm.com.au/imagelibrary/thumbnails/Candida-150.jpg

Budding - Hydra http://www.bbc.co.uk/schools/gcsebitesize/img/bihydra.gif http://www.youtube.com/watch?v=5gXu-4ABXNA&safety_mode=true&persist_safety_mode=1

Binary Fission-equal division of cytoplasm-paramecium and bacteria http://www-biol.paisley.ac.uk/courses/Tatner/biomedia/jpegs/conjug2.jpg http://wappingersschools.org/RCK/staff/teacherhp/johnson/visualvocab/BinaryFissionParamecium.jpg

What is this?? http://www.moldbacteria.com/Ryebread2.gif

Spore formation- asexual in fungus. Ex : Bread mold http://www.astrographics.com/GalleryPrints/Display/GP2055.jpg http://www.sciencenmore.com/brmold.jpg

http://www.rogers.k12.ar.us/users/ehutches/tigerbreadmold1.jpg

Regeneration- ability to grow back body parts http://www.vsf.cape.com/~jdale/science/starfishregenerating.jpg

Regeneration Planarian California Black Worm                 Planarian California Black Worm http://www.eeob.iastate.edu/faculty/DrewesC/htdocs/lvregencolor.JPG http://islandwood.org/kids/stream_health/macros/Planaria.html

Asexual Reproduction: advantages and disadvantages 1. Produces many offspring in a short period of time. 2. Don’t need to waste time and energy finding a mate. 3. In a changing environment, they lack the ability to adapt. http://www.microscope-microscope.org/gallery/hydra-187h.jpg

Sexual Reproduction: advantages and disadvantages 1. Provides genetic variation. 2. More able to survive in a changing environment-evolution. 3. Need to find a mate. 4. Requires more time and energy

Sexual Selection http://fm1.fieldmuseum.org/aa/Files/patterso/File0737-s.jpg http://www.bees.unsw.edu.au/images/user/staff/prykeweaverbirds1.jpg

Why does the male peacock have a long, heavy tail? Sexual Selection Why does the male peacock have a long, heavy tail? www.djibnet.com/photo/hamilton/peacock-tail-long-view-1-of-4-3318816038.html

Sexual Selection Humans select for certain traits too!

Review Question 12. Name three different types of asexual reproduction. 13. What are the advantages of asexual reproduction? 14. What are the advantages of sexual reproduction?