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comparing mitosis and meiosis. (it can be both for some of them)

two cell divisions. (mitosis/meiosis/both) ?

dna replication. (mitosis/meiosis/both) ?

chromosomes pair up. (mitosis/meiosis/both) ?

spindle fibers form. (mitosis/meiosis/both) ?

one cell division. (mitosis/meiosis/both) ?

cytokinesis. (mitosis/meiosis/both) ?

four daughter cells. (mitosis/meiosis/both) ?

Verified Answer :

0dessa
  1. two cell divisions = meiosis. 
    In meiosis one 2n (diploid) cell divides into 4 n (haploid) genetically diverse cells. There are two divisions. 1 -> 2 -> 4. In mitosis one diploid cell divides into two identical diploid cells, so there is only one division.

    2. DNA replication = both!
    In the life cycle of any cell (cell cycle), during the synthesis period of interphase DNA replication occurs. Cells have unduplicated chromosomes in G1 (before replication/synthesis) and duplicated chromosomes in G2 (after replication/synthesis). In mitosis, they are replicated so that the chromosomes can be split into two cells (duplicated chromosomes are ripped in half, so the daughter cells have unduplicated chromosomes after cell division). In meiosis, they are also replicated for the same reason, but the homologous pairs are additionally split up so that the four daughter cells are all haploid.

    3. chromosomes pair up = meiosis
    In meiosis the additional "sorting" of genetic information happens because 1 diploid cell is going to make 4 haploid cells. The homologous pairs find their mate and during metaphase I the homologous chromosomes line up in pairs and one of each pair is divided into the first division of cells. This "pairing up" happens in prophase I of meiosis and is called "synapsis"!

    4. spindle fibers form = both!
    In both mitosis and meiosis the spindle fibers come out from the centrosomes and attach to the chromosome halves in mitosis and meiosis II and attach to each chromosome of the homologous pairs in meiosis I. The basic process of division is the same in both.

    5. one cell division = mitosis
    See my answer for #1.

    6. cytokinesis = both!
    Cytokinesis is the splitting of the cytoplasm and the essence of "cell division," which happens in both mitosis and meiosis. It just happens twice in meiosis.

    7. four daughter cells = meiosis
    In meiosis one diploid (2n) somatic cell divides to form 4 genetically diverse haploid (n) gamete cells. Remember this!

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