meiosis
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Meiosis. Meiosis – germ cell go through 2 nuclear divisions that results in 4 daughter cells with half the number of chromosomes as the parent cell. Explains how gametes are produced daughter cells are not genetically alike. may have different combination of genes. - PowerPoint PPT PresentationTRANSCRIPT
Meiosis • Meiosis – germ cell go through 2 nuclear
divisions that results in 4 daughter cells with half the number of chromosomes as the parent cell.
– Explains how gametes are produced
• daughter cells are not genetically alike. – may have different combination of genes
• Sexually reproducing organisms are capable of combining chromosomes from 2 parents to produce offspring.
• The chromosomes that combine during sexual reproduction are contained in reproductive cells called gametes.
• Control of the Cell Cycle• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__control_of_the_cell_cycle.html
• Activity: 25 point extra creditGo to the onion root tip activity and complete the percentages activity. • http://www.biology.arizona.edu/Cell_bio/activities/cell_cycle/cell_cycle.html
• Mitosis Rap• http://www.nclark.net/MitosisRap.mp3
• Mitosis Animation and Tutorialhttp://www.biology.arizona.edu/Cell_bio/tutorials/cell_cycle/cells3.html
• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html
http://www.sumanasinc.com/webcontent/animations/content/mitosis.html
• Meiosis• http://www.youtube.com/watch?v=D1_-mQS_FZ0
http://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter19/animation__how_meiosis_works.html • http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter12/animations.html#
• Mitosis vs Meiosishttp://www.johnkyrk.com/meiosis.html
http://www.pbs.org/wgbh/nova/baby/divide.html#
http://www.pbs.org/wgbh/nova/baby/divi_flash.html
• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__comparison_of_meiosis_and_mitosis__quiz_1_.html
•
Meiosis
• like mitosis, meiosis follows Interphase and
ends with cytokenisis
• The 1st meiotic division results in two cells with ½ the number of chromosomes as the parent cell.
• The 2nd meiotic division is like mitosis; the number of chromosomes does not get reduced. Results in 4 daughter cells with half the # of chromosomes as the parent cell
Prophase I• each chromosomes consist of
two sister chromatids connected at the centromere
• Homologous pairs of chromosomes come together, this event is called synapsis
• Each pair of homologous chromosomes is called a tetrad. (4 chromatids that make up a homologous pair)
• Crossing over – exchange of genes between non- sister chromatids of a homologous pair
• results in genetic recombination by producing a new mixture of genetic material.
Metaphase I
• Homologous pairs (tetrads) align in the middle of the cell.
Anaphase I
• homologous pairs separate and move to opposite ends of the cell.
– Each chromosome consist of 2 chromatids
Telophase I• Spindle fibers break down• 2 new nuclei form
– One around each set of chromosomes
– ½ the number of chromosomes as the original (parent) cells
– End of Meiosis I
Meiosis II
Prophase II• Spindle fibers form
Metaphase II
• chromosomes line up at the equator
Anaphase II
• sister chromatids separate at the centromere and move to opposite poles
ttp://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter19/animation__how_meiosis_works.html
Telophase II
• 4 new nuclei appear; one around each set of chromosomes
• followed by
cytokenesis
• end up with 4 cells that are all haploid with only 1 chromatid for each chromosome
• Review
• http://www.biology.arizona.edu/cell_bio/tutorials/meiosis/problems.html
Meiosis - Males
Meiosis in Females
• Meiosis II• prophase II: spindle fibers attach to the duplicated
chromosomes and begin moving them to the spindle equator.
• metaphase II: chromosomes align at the cell equator with one chromatid facing one pole and the other chromatid facing the opposite pole.
• anaphase II: the chromatids separate and are now called chromosomes. The chromosomes migrate toward the two poles.
• telophase II: the chromosomes arrive at the opposite poles, and the cytoplasm divides. The two meiotic divisions result in four haploid cells.