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Mitosis and the Cell Cycle

Updated on January 1, 2013

Mitosis

  • Mitosis is the process in which two genetically identical daughter cells are produced form one parent cell nucleus.

  • This process is divided into 6 stages which occur in the following order:

  • Interphase - Prophase - Metaphase - Anaphase - Telophase - Cytokinesis

  • Below I will go into more detail about each individual stage and what occurs during it.

Interphase

Most Eukaryotic cells spend the majority of their time in this phase.

During interphase there are 3 separate stages:

G1:

  • During this stage the cell 'grows' and a lot of protein synthesis occurs.
  • The chromosomes are all unreplicated and each contains only one molecule of DNA.

S:

  • This is the period when the cell replicates its DNA
  • Once this stage has been completed all of the chromosomes have two chromatids.

G2:

  • Growth continues and the organelles replicate in preparation for the cell to divide during mitosis.
  • The proteins necessary for cell division (such as those that form the microtubules/spindle fibres) are produced.

Prophase

  • In prophase the chromosomes shorten and thicken and become visible under a light microscope.

  • The nuclear envelope breaks down and disappears.

  • The centriole (an organelle in the cell) divides into two and each part moves to different poles of the cell to form the spindle.

  • The centrioles are made of protein threads.

Metaphase

  • The pairs of homologous chromosomes are now as tightly coiled and condensed as they will be in meiosis.

  • The chromosomes move to the central region of the spindle (equator).

  • The chromosomes become attached to the spindle thread by its centromere.

  • The centromere is the part of the chromosome that links the sister chromatids.

Anaphase

  • In this stage the centromere that holds together the sister chromatids split.

  • This effectively makes each 'sister' chromatid an individual chromosome.

  • Both chromosomes are identical to each other an and the parent cell from which it was copied.

  • The spindle fibres that are attached to the chromosomes shorten and pull the chromosomes towards the opposite poles of the cell.

Telophase and Cytokinesis

  • As the separated chromosomes reach the opposite poles of the cell a new nuclear envelope forms around each set.

  • The spindle breaks down and disappears.

  • The chromosomes uncoil and once again become not visible under the light microscope.

  • The whole cell splits into two to form two new cells containing full sets of chromosomes, this is called cytokinesis.

The Cell Cycle

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    • Anthropophobia profile image
      Author

      Anthropophobia 4 years ago

      Thank you, I'm glad that it could be of use to you.

      Good luck with the lecture!

    • Joyus Crynoid profile image

      Joyus Crynoid 4 years ago from Eden

      Nice summary with good illustrations--I will provide my students with the url to this in a lecture that I'm giving in a couple of weeks, in a short course on developmental biology.