The Cell Cycle

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A eukaryotic cell cannot divide into two, the two into four, etc. unless two processes alternate:

  • doubling of its genome (DNA) in S phase (synthesis phase) of the cell cycle;
  • halving of that genome during mitosis (M phase).

The period between M and S is called G1; that between S and M is G2.


So, the

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Mitosis

When a eukaryotic cell divides into two, each daughter or progeny cell must receive

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Polyploidy

Cells (and their owners) are polyploid if they contain more than two haploid (n) sets of chromosomes; that is, their chromosome number is some multiple of n greater than the 2n content of diploid cells. For example, triploid (3n) and tetraploid cell (4n) cells are polyploid.

Polyploidy in plants

Polyploidy is very common in plants, especially in