Jeremy has a master of science degree in education.
Cell Division: Mitosis and Meiosis
In very basic terms, mitosis and meiosis are fancier sounding ways to say cell division. That is the easy way to put it. Mitosis and meiosis are anything but simple or easy, and they are very important. Mitosis is the way that a cell copies its DNA so that it can split into two identical cells. Meiosis is a similar process that has two processes, Meiosis I and II, and results in four cells that are identical to each other, but not to the original cells. This is how sex cells are formed.
During mitosis and meiosis I (which I will simply refer to as cell division), there are a number of different phases in which different processes occur. Each phase needs to be completed before the cell moves into the next phase. One of these phases is the metaphase, when the metaphase plate assembles. Remember, this all occurs rather quickly and almost constantly, as many of our cells are always creating new forms of themselves.
Metaphase and the Metaphase Plate
The entire process of cell division involves six phases (interphase, prophase, prometaphase, metaphase, anaphase, and telophase). Metaphase is the 4th phase of cell division. At this point in cell division, the centrosomes (responsible for microtubule organization) are lined up at either end of the cell. Attached to the centrosomes are microtubules that connect over to the kinetochores. The kinetochores are specialized proteins found on the centromere section of the chromatids.
A chromatid is one half of a chromosome, and the center where a chromatid connects to its sister chromatid (to form a chromosome) has a region called the centromere. So let's recap: chromatids are one half of a pair that make up a chromosome. The centromere is the region where chromatids attached to one another. And the kinetochore is a special protein found here in the centromere, connected by microtubules to the centrosomes.
If you were to draw an imaginary line across the cell, as a diameter (line stretching from one side of a circle to the other passing through the center) you would have the metaphase plate. This imaginary line is the axis where all of the chromosomes line up literally in a row. It is here where they organize and finally begin to separate. It plays an important role because it allows the cell to assemble and then divide the chromatids.
To sum it up, the metaphase plate is simply an imaginary plane that exists only during metaphase. It draws a line across the cell that is equidistant from both poles of the cell. This allows the chromosomes a place to be lined up on before they are pulled apart.
Think of it as lining up before recess in elementary school. You all got into a line and the teacher walked you outside where you took off in different directions. It could also be looked at as the start of kickball. The physical education teacher placed all the balls in the middle and you ran towards the middle pulling some balls back with you.
Metaphase is a stage of cell division where the chromosomes line up along the metaphase plate. The metaphase plate is an imaginary line that runs across the cell, dividing the cell into hemispheres. As the chromosomes line up here, they begin to separate into individual chromatids and are drawn towards opposite poles. The cell then moves into its next stages before completing the division. The metaphase plate plays an important role as this where the chromosomes gather and organize before being split apart.
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