Mitosis/Meoisis

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Just want key points or a summary about the differences between both.

Posted Sun 28th April, 2013 @ 21:24 by Yaz

2 Answers

  • 2 votes

Mitosis occurs in your body cells.

Used for:

  • Asexual reproduction
  • Growth of an organism
  • Repair of damaged tissue

The mitotic cycle involves the stages:

  • Interphase - cell growth, synthesis of organelles and DNA replication
  • Prophase - Chromosomes condense, centrioles move to poles of the cell, nuclear envelope disappears
  • Metaphase - Chromosomes line up on the equator of the cell
  • Anaphase - Centromeres split, the two previously joined sister-chromatids become chromosomes, chromosomes move to the poles
  • Telophase - Nuclear envelope reforms around chromosomes, cleavage furrow forms, cells split (cytokinesis)

Mitosis produces two genetically identical daughter cells. ...... they are clones ....

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Meiosis is used to produce gametes.

It has two main stages, called meiosis 1 and meiosis 2 ....  pretty simple!

Meiosis I:

  • Prophase I - Chromosomes condense, chromosomes pair up in homologous pairs to form bivalents, 'crossing over' takes place, centrioles move to poles of cell, nuclear envelope disappears
  • Metaphase I - Homologous pairs line up on equator
  • Anaphase I - Chromosomes split from their homologous pairs, centromeres do not divide, chromosomes pulled towards the poles of the cell
  • Telophase I - Nuclear envelope reforms around chromosomes, cleavage furrow forms, cells split (cytokinesis)

At this stage you have 2 diploid cells - they have a full set of chromosomes - 43 (or 23 pairs). But the cells need to be haploid - have half the number of chromosomes - 23.

So these two cells split again....

Meiosis II:

  • Prophase II - Nuclear envelope disappears, chromosomes condense, centrioles move to poles of cell
  • Metaphase II - Chromosomes line up on the equator of the cell
  • Anaphase II - Centromeres do split, chromosomes move to the poles of the cell
  • Telophase II - Nuclear envelope reforms, cleavage furrow forms, cell splits (cytokinesis)

Now you have 4 genetically DIFFERENT haploid cells - with half the number of chromosomes - 23 - these are the gametes

So when two gametes fuse, the resulting cell has a full set of 46 chromosomes!

Answered Mon 29th April, 2013 @ 23:51 by Charlotte
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Mitosis is making two identical cells from the original one, so like M.I.T.O.S.I.S- Making Two Identical.

Meiosis is making eggs (sex cells), so like M.E.I.O.S.I.S - Making Eggs

Mitosis involves the cell to copy the 23 pairs of chromosomes, then the cell splits into two identical new cells, with a copy of the 23 pairs of chromosomes going to each cell

Meiosis involves the cell to copy the 23 chromosomes again, but I think splits and the splits again? I'm not quite sure how that works (I can't think!), but I know that you end up with 4 gametes (sex cells) which only have 23 actual chromosomes each, rather than the 46 full chromosomes (23 pairs) that the normal body cells. This means that when the gamete fuses with another gamete (egg and sperm), they form a normal body cell with the full 23 pairs of chromosomes?

I think... :)

Answered Mon 29th April, 2013 @ 12:56 by Lara