1 / 10

Meiosis

Meiosis . Section 11-4 Pages 275-278. Meiosis. Meiosis—the process of reduction division in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell. Chromosome Number. Human—46 chromosomes 23 from male parent

austin
Télécharger la présentation

Meiosis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Meiosis Section 11-4 Pages 275-278

  2. Meiosis • Meiosis—the process of reduction division in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell

  3. Chromosome Number • Human—46 chromosomes • 23 from male parent • 23 from female parent

  4. Homologous—chromosomes that each have a corresponding chromosome from the opposite-sex parent • Diploid—cells that have both sets of homologous chromosomes (2N) • For humans diploid number is 46 (2N=46)

  5. Chromosome Number • Gametes (sex cells) contain only a single set of chromosomes • Haploid—cells (gametes) that contain only a single set of chromosomes (N) • For humans haploid number is 23 (N=23) • Will you find haploid cells within the skin on your arm? Why or why not?

  6. Phases of Meiosis I • Prior to meiosis I each chromosome is replicated (DNA replication) • Meiosis I looks very similar to mitosis • Prophase of meiosis I—each chromosome pairs with its corresponding homologous chromosome to from a tetrad • 4 chromatids to a tetrad

  7. Meiosis I • Crossing-over—portions of chromatids are exchanged while in tetrads • Metaphase I—tetrads line up across middle of cell • Anaphase I—homologous chromosomes are seperated • Because of separation of homologous chromosomes new daughter cell has only one copy of each chromosome

  8. Meiosis II • Two cells produced by meiosis I enter another meiotic division • No replication takes place • Each cell contains 2 sister chromatids • Metaphase II—chromosomes line up in the center of each cell • Anaphase II—the paired chromatids separate • Each of the 4 daughter cells produced in meiosis II contain the haploid number of chromosomes – in people N=23

  9. Comparing Mitosis and Meiosis • Mitosis results in the production of two genetically identical diploid cells, whereas meiosis produces four genetically different haploid cells • Mitosis—two diploid (2N) daughter cells • Meiosis—four haploid (N) cells

  10. Picture Credits • http://employees.csbsju.edu/hjakubowski/classes/ch331/dna/chromosomes.gif • http://www.microscopix.co.uk/chromosomes/16306.gif • http://www.emc.maricopa.edu/faculty/farabee/biobk/meiosisover.jpg • www.distance.stcc.edu/.../celldivision/tetrad.gif • http://www.cancerquest.emory.edu/images/mitosis-cycai.gif • http://www.palaeos.com/Fungi/Lists/Glossary/Images/Meiosis.gif

More Related