Ploidy Number

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    • #9206
      Tokophyra125
      Participant

      For some reason "calculating" the diploid and haploid number of an organism/cell is messing me up. If I have a cell with four pairs of homologous chromosomes, the diploid number should be four, right? Also, if there is an organism with a haploid number of X then what would the number for a bivalent, sister chromatid, and a nucleus after DNA replication be?

    • #82436
      Tokophyra125
      Participant

      Sorry, rather a diploid number of 4.

    • #82574
      biogeek02
      Participant

      Check out http://www.bioinmotion.com for cool vids about meiosis and mitosis!

    • #82579
      Cat
      Participant
      quote Tokophyra125:

      For some reason “calculating” the diploid and haploid number of an organism/cell is messing me up. If I have a cell with four pairs of homologous chromosomes, the diploid number should be four, right? Also, if there is an organism with a haploid number of X then what would the number for a bivalent, sister chromatid, and a nucleus after DNA replication be?

      The whole thing is wrong.

      Vocabulary:

      Haploid – half of total number of chromosomes
      Mono– one
      Di – Two
      Tetra – four
      Octa – eight

      Cell that has only 1 set of chromosomes (no sister chromatids) is monoploid. Monoploid is sometimes treated as synonym of haploid when haploid number happens to be 1.

      Cell that has 2 of each chromosome (like humans) are diploid.

      Cells from your example, that have four pairs of homologous chromosomes in reality have 8 copies of each chromosome and, therefore, octaploid.

      Haploid cell will have half of chromosomes in original somatic cell. So if original is diploid (2n), haploid is 1n; if original is octaploid (8 of each chromosome), haploid has 4 sets of each chromosome.

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