Practice Quiz Which of the following options shows the correct order of the steps of mitosis? Show Answer Answer a is correct. If you answered b, you might be having some trouble keeping the beginning steps in order. If you answered c, you might be having some trouble keeping the steps in the second half of mitosis in order. Show Answer The cell shown above is in prophase.
In prophase, the first step in mitosis, the nuclear envelope breaks down and chromosomes condense and become visible. Show Answer The cell shown above is in metaphase. Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article.
Provided by the Springer Nature SharedIt content-sharing initiative. Skip to main content. Search SpringerLink Search. Abstract The formation of kinetochore chromosomal and continuous fibers, and the behavior of the nuclear envelope NE was described in studies combining light and electron microscopy.
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Google Scholar - -Mitosis and mitotic factors, 16 mm film, Google Scholar Beyer, H. Google Scholar Branton, D. Google Scholar Brinkley, B. Google Scholar Davies, H. Google Scholar Fisher, H. Google Scholar Forer, A. Google Scholar Franke, W. Google Scholar Gall, J. Google Scholar Gay, H. Google Scholar Harris, P. Google Scholar Jenkins, R.
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Google Scholar Steward, D. Google Scholar Szollosi, O. The spindle is necessary to equally divide the chromosomes in a parental cell into two daughter cells during both types of nuclear division: mitosis and meiosis. During mitosis, the spindle fibers are called the mitotic spindle.
Meanwhile, during meiosis, the spindle fibers are referred to as the meiotic spindle. At the beginning of nuclear division, two wheel-shaped protein structures called centrioles position themselves at opposite ends of the cell forming cell poles.
Long protein fibers called microtubules extend from the centrioles in all possible directions, forming what is called a spindle. In this way the spindle fiber appears to move, or "pull" the chromosome around. This process can be stopped by adding drugs such as colchicine, when the spindle appears to "freeze" in place. Some of the microtubules stretch from the MTOC region directly to the individual chromosomes. Each half of the chromosome, the sister chromatids, has a granule located somewhere near the centromere.
This is the kinetochore , and is the place where the spindle microtubules attach. The microtubules attached to the kinetochore and the MTOC shorten and pull on the chromosome. Since the chromosome is attached to two sets of fibers, pulling in opposite directions, the whole chromosome structure is tugged into the center of the cell, where all of the kinetochores of all the chromosomes line up.
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