1 / 10

Meiosis: The reason why we are all unique

Meiosis: The reason why we are all unique. Meiosis occurs in two main phases Meiosis I Meiosis II. Meiosis: The reason why we are all unique. Big Ideas: The number of chromosomes per cell is cut in half from diploid to haploid Crossing over creates new combinations of alleles

ailish
Télécharger la présentation

Meiosis: The reason why we are all unique

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:The reason why we are all unique Meiosis occurs in two main phases Meiosis I Meiosis II

  2. Meiosis:The reason why we are all unique Big Ideas: The number of chromosomes per cell is cut in half from diploid to haploid Crossing over creates new combinations of alleles Meiosis I results in 2 daughter cells with new allele pairings Meiosis II results in 4 haploid gametes (with half the number of chromosomes) Haploid gametes merge (fertilization) to create a diploid zygote

  3. The phases of meiosis – MEIOSIS I • Interphase - Chromosomes in diploid cells replicate to make sister chromatids.

  4. The phases of meiosis – MEIOSIS I • Prophase I -Replicated chromosomes pair up with corresponding chromosomes and form a TETRAD • Chromatids of homologous chromosomes literally cross over • The crossed sections (which contain alleles) are exchanged - Crossing over creates new combinations of alleles.

  5. The phases of meiosis – MEIOSIS I • Metaphase I and Anaphase I • Paired homologous chromosomes line up on the metaphase plate • Each homologous chromosome pair is pulled to opposite sides of the cell.

  6. The phases of meiosis – MEIOSIS I • Telophase I and Cytokinesis • Nuclear envelope reforms around each cluster of chromosomes • Cell membrane pinches the cytoplasm creating two new daughter cells • When cytokinesis in complete, there are two haploid daughter cells that are genetically different.

  7. The phases of meiosis – MEIOSIS II • Prophase II • Chromosomes become visible in both diploid daughter cells • NO Tetrads because homologous pairs have already separated

  8. The phases of meiosis – MEIOSIS II • Metaphase II Chromosomes line up in the center • Anaphase II Spindle fibers pull paired chromatids apart • Telophase II Nuclear envelope reforms • Cytokinesis 4 haploid daughter cells are formed

  9. The phases of meiosis – MEIOSIS II

  10. The phases of meiosis – MEIOSIS II What do you notice about the chromosomes in the 4 haploid daughter cells? 2. Go back to slide 4 (Prophase I). What are the genotypes of the chromosomes in the tetrad? What are the genotypes of the 4 gametes? 3. Why do you think meiosis is described as the reason why we are all unique?

More Related