(2) In meiosis, first division is reductional (separation of non-sister chromatids) and second division is equational (separation of sister Chromatids). The mitotic division is purely equational. Due to crossing over during first meiotic division, separation in first meiotic division may be partly equational also. In these regions where first division becomes equational due to crossing over, second division will now be reductional.
(3) In meiosis, homologous chromosomes undergo pairing. This pairing involves not more than two homologous chromosomes in a particular region of the chromosome, as would be evident in a autopolyploid having more than two sets of homologous chromosomes (Fig. 7.11). In mitosis, on the other hand, no chromosome pairing takes place. The only exception is giant salivary gland chromosomes, which pair throughout their lengths and may involve more than two homologous chromosomes in the same region, thus showing a distinct difference from meiotic pairing.
(4) In meiosis, with each pair of homologous chromosomes forming a bivalent, a tripartite structure called synaptonemal complex is observed under electron microscope. This structure appears at zygotene, persists in pachytene and disappears in diplotene. No such structure is observed in mitosis.
(5) In meiosis, synthesis of small fraction of DNA (0.3%) is not completed in S phase, but is delayed till zygotene. No such delayed synthesis of DNA is observed in mitosis.
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