Unit 9 (Meiosis)

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Across
  1. 5. type of reproduction in which two haploid (n) gametes from two parents unite to form the first cell of a new organism
  2. 6. This process is part of the Telophase (Stage 5) and Telophase II (Stage 9).
  3. 9. cell that contains only a single set of chromosomes and therefore only a single set of genes; reproductive cells are haploid
  4. 11. containing two complete sets of chromosomes, one from each parent; a zygote formed by sexual reproduction is diploid
  5. 12. Notice that we skip interphase this time around because there is no replication of DNA between Meiosis I and Meiosis II. at this point the chromosomes reorganize and the nuclear membranes start to dissolve again. Sister chromatids are again joined by a centromere. Spindles start to reform between centrosomes.
  6. 14. Nuclear membranes start to form around the chromosomes again. A cleavage forms. Cytokinesis occurs and the two diploid cells have now divided into 4 haploid cells. In males this equals 4 sperm. In females this creates 1 egg and 3 polar bodies which are useless in humans.
  7. 15. any cell of a living organism other than the reproductive cells.
  8. 18. Homologous Chromosomes (matching chromosomes from mom and dad) join up together and sometimes share genetic information. Happens during stage 2, Prophase I.
  9. 19. Spindle fibers are completely formed and attach to the centromeres of the homologous chromosomes. the chromosomes line up down the middle of the spindles along with their homologous pair.
Down
  1. 1. At this point the spindle fibers start to pull on the chromosomes and each homologous chromosome heads towards a different pole.
  2. 2. Creates 4 haploid gamete cells from a diploid cell.
  3. 3. mature, haploid (n) sperm (male) or egg (female) cells; join during sexual reproduction to produce a diploid (2n) zygote
  4. 4. Matching chromosomes from mother and father.
  5. 7. The DNA starts to coil itself up into visible chromosomes. The copies of each chromosome (sister chromatids) are connected together by a centromere. during the end of this stage the nuclear membrane starts to dissolve, centrosomes move towards the poles, and spindle fibers start to form. Crossing over occurs during this stage.
  6. 8. a diploid (2n) cell resulting from the fusion of two haploid (n) gametes; a fertilized ovum.
  7. 10. The spindles pull the sister chromatids apart. Each goes towards a different pole.
  8. 13. Spindles are fully formed again and attach to the centromeres. The chromosomes line up down the middle of the spindles.
  9. 16. Chromosomes are now at the pole, nuclear membranes start to form around the chromosomes, and the chromosomes start to unwind back into chromatin. Cytokinesis occurs and the two cells split. These two cells are still diploid at this point. The next 4 phases occur to each of these cells.
  10. 17. At this point the DNA is in its chromatin form and the DNA replicates.