Bio - Lecture 10a (NEW EXAM)

Bio - Lecture 10a (NEW EXAM) -...

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Sheet1 Page 1 Meiosis Lecture 10a Gametes and Somatic cells Gametes are the reproductive cells of an organism (i.e. sperm or egg) -These are haploid Somatic cells are the rest of the organism's cells -These are diploid During fertilization (syngamy), the egg and sperm fuse making a zygote (diploid) Reduction Division aka Meiosis Gametes must contain a haploid number of chromosomes to ensure the somatic cells (zygote) contain the correct number of c h There must also be a reduction from diploid to haploid before fertilization otherwise the zygote would have too many chromos o m This reduction division is called Meiosis Purpose of Meiosis is to reduce the number of chromosomes to Haploid to avoid complications Sexual Life Cycle Many organisms use mitosis, meiosis, and fertilization in a reproduction cycle This is called sexual reproduction
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Unformatted text preview: -Fertilization-Mitosis-Meiosis-Cycle Repeats Meiosis Overview In animal cells, meiosis occurs in two stages-Meiosis I and Meiosis II Each stage has prophase, metaphase, anaphase and telophase There are major differences between mitosis and meiosis besides reductions division-Homologous (not identical, but similar to one another) chromosomes associate with one another in a process called synapsis This lasts throughout Meiosis I Because of synapsis, -crossing over- occurs-This is when sections of homologous chromosomes exchange places->Also called recombination->It occurs at sights called chiasmata-->Called such because of the greek letter Chi (X) Remember, meiosis involves two rounds of cell division and only one round of chromosome replication Mitosis involves one round of each...
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This note was uploaded on 05/06/2008 for the course BIOL 121 taught by Professor Lopez during the Fall '07 term at Lansing.

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