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1.6.1. Mitosis

Mitosis

The mitosis is a process of dividing the core in which are distributed equitably chromosomes (DNA strands) between the two daughter cells, so they have the same genetic information and also mirrors that of the cell that originated.

Remember that before mitosis begins, at the interface, the DNA has been duplicated, although the chromosomes have not yet formed.

The mitosis, in beings unicellular and multicellular some, is a mechanism of asexual reproduction by can increase the number of individuals in the population. On the other hand, in multicellular beings, mitosis allows new cells to appear so that the individual can grow or to replace those that are dying.

The mitosis is a continuous, uninterrupted, but for study is divided into four phases:

Prophase

The main events that occur during prophase are:

  • Chromatin begins to condense forming chromosomes.

  • The nuclear envelope fragments until it disappears.

  • The nucleolus disappears, dispersing in the cytoplasm.

  • Each centriole, duplicated at the interface, travels to one end of the cell. Between them, the achromatic spindle is formed, a few protein filaments.

  • The chromosomes, are attached to a spindle fiber achromatic by the centromere, so that chromatids are oriented toward the poles of the cell.

  • The chromosomes, once attached to the fibers of the spindle, move towards the center of the cell.

Remember that plant cells do not have centrioles, but the filaments of the achromatic spindle are also formed.

Profase

 

Metaphase

The metaphase is the phase with the longest duration, and the main events that occur are:

    • The chromosomes are already fully condensed and are located in the center of the cell, forming the equatorial plate.
    • Chromosomes are attached to the fibers of the achromatic spindle by the kinetochore of each chromosome.

Metafase

By LadyofHats [Public domain], via Wikimedia Commons

Anaphase

The main events that occur during anaphase are:

  • The chromatids of the chromosomes are separated at the centromere because the fibers of the achromatic spindle are shortened. Each chromatid is directed towards a centriole , located one at each pole of the cell.
  • The same number of chromatids go to each pole of the cell, since the chromosomes have been divided into two chromatids.

Telophase

The main events that occur in telophase are:

At this point, mitosis would end, but as anaphase ends, cytokinesis begins.

Telofase

By LadyofHats [Public domain], via Wikimedia Commons

Interactive activity: Order the phases of the cell cycle.

Interactive activity: Mitosis.

Shakira's song: Mitosis. With subtitles.

Julinky's Song: Mitosis 

Game: Mitosis Move.

Game: Cell mitosis.