• Question: does it take a certain time for cell to multiply?

    Asked by iluvwilmas to Adam, Joanna, Louise S, Marcus on 21 Nov 2012.
    • Photo: Joanna Giles

      Joanna Giles answered on 21 Nov 2012:

      Yes it does! Cells have their very own growth cycle – it is called the “Cell Cycle” and they undergo different phases and they have “checkpoints” at each stage to make sure that the last stage is fully completed.

      The cell cycle consists of a Growth phase (called G1), a DNA synthesis phase (called S1 to allow the genes to multiply so that when the cells split they both have the correct number of genes), a G2 phase that allows for extra growth and an Mitosis phase (M phase) where the cell actually splits into two. This whole process takes time, and the time is different for different cells and different organisms. Generally for fast dividing mammalian cells it is around 24 hours.

      Cells can “rest” though, if they are not dividing and they go into a phase called G0 (which can sometimes occur after G1) and wait until they receive the right signals to continue with the cycle.

      In cancer, sometimes the “checkpoint” are broken and this is when the cells divide uncontrollably even though they are not supposed to be.

    • Photo: Marcus Wilson

      Marcus Wilson answered on 21 Nov 2012:

      yes it does. bacteria can take as little as twenty minutes, and early on cells in embryos replicate every couple of hours. when there is lots of resources availible, and no blocks on the cells, they will replicate as quickly as they can replicate their DNA, as this is the slowest step in the cell cycle.

      how cells replicate is very highly controlled, and in our bodies it doesnt happen very often, and even then only n speciliased cells ( called stem cells)

    • Photo: Adam Paige

      Adam Paige answered on 22 Nov 2012:

      How fast cells multiply also affects how we heal from wounds. Cells in our hearts or nerves or brain are in the rest phase (G0) that Joanna mentioned, and they never come out of it. So these cells will not divide and multiply, and therefore if our heart or nerve cells are damaged they will never be repaired or replaced.

      Other tissues like our bone marrow which makes the blood cells, or the epithelial cells of our skin or intestines, have cells in them that divide all the time (adult stem cells). These tissues are continually making new cells to replace old and damaged cells. And therefore, when we have a wound in these tissues (like a cut in our skin) it heals very quickly.

      Most of our tissues (like our liver and kidneys) lie between these two extremes. The cells CAN divide and repair, but they are not usually dividing – only if the tissue is damaged and needs new cells to be made.

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