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Sexual Reproduction and Meiosis . Sexual Reproduction. How new organisms are produced 2 new cells come together Formed from cells in reproductive organs. Sex Cells in Humans. Male reproductive organs contain sex cells called sperm.
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Sexual Reproduction • How new organisms are produced • 2 new cells come together • Formed from cells in reproductive organs
Sex Cells in Humans • Male reproductive organs contain sex cells called sperm • Female reproductive organs contain sex cells called eggs
Meiosis I • Chromosomes become duplicated • There are 4 Phases: Prophase I, Metaphase I, Anaphase I and Telophase I
Prophase I • Duplicated chromosomes are visible under a microscope as a chromatid • Duplicated chromosome comes near its duplicated mate
Metaphase I • Duplicated chromosome pairs line up in center of cell • The centromere of each pair becomes attached to one spindle fiber • The chromatids do not separate
Anaphase I • 2 pairs of chromatids move away to opposite ends of the cell • Duplicated chromosome still have 2 chromatids
Telophase I • The cytoplasm divides • 2 new cells form • New cell has 1 duplicated chromosome from each similar pair
Meiosis II • Begins after 2 new cells form in Meiosis I • Chromatids of each chromosome will be separated during this division • Occurs in 4 phases: Prophase II, Metaphase II, Anaphase II, Telophase II
Prophase II The duplicated chromosomes and spindle fibers reappear in each new cell
Metaphase II • Duplicated chromosomes move to the center of cell • Each centromere attaches to 2 new spindle fibers
Anaphase II • Centromere divides • Chromatids separate and move to opposite ends of the cell • Each chromatid is now an individual chromosome
Telophase II • Spindle fibers disappear • Nuclear membrane forms around the chromosomes at each end of the cell • Cytoplasm divides
How Fast Does Meiosis Happen? • Just how fast does meiosis happen? • Is it faster than a car going 100 mph or is it slower than a turtle crawling? • Lets find out!
Meiosis! Meiosis! Meiosis! • Now that you are an expert on Meiosis, let’s see how well you can identify each step • Name each of the following steps from Meiosis I or II.
Name this step. Metaphase 2! That’s right!
Which step is this? Telophase I! That’s right!
Is this step from Meiosis I or II? Meiosis I! That’s right!
Meiosis! • Cells have been divided, chromosomes duplicated, we have reached the end of meiosis…. • See you next class!
Webliography • Pictures taken from Microsoft Clip Art • http://www.sumanasinc.com/webcontent/animations/content/meiosis.html • http://www.uic.edu/classes/bios/bios100/lecturesf04am/prophase1m.jpg • www.biologycorner.com/bio1/qz_meiosis.html • Information taken from Glencoe LifeScience Book A • http://videos.howstuffworks.com/hsw/5988-mitosis-and-meiosis-metaphase-one-video.htm • http://www.usd.edu/~bgoodman/cell.JPG