Select all that apply
Choose all of the following events that occur during prophase of mitosis.
Chromosomes condense.
Nuclear envelope disappears.
Spindle fibers grow from the centrioles.
Chromosomes migrate to opposite poles.
Centrioles are pushed apart.
The Correct answer and Explanation is:
During prophase of mitosis, the following events occur:
- Chromosomes condense.
- Nuclear envelope disappears.
- Spindle fibers grow from the centrioles.
- Centrioles are pushed apart.
Explanation:
Prophase is the first stage of mitosis, a process by which a cell divides its genetic material to produce two identical daughter cells. The events occurring during prophase are crucial for ensuring proper chromosome segregation.
- Chromosomes condense: In prophase, the chromatin fibers, which are loosely organized, begin to coil and condense into distinct, visible chromosomes. Each chromosome consists of two sister chromatids joined at a region called the centromere. This condensation is essential as it allows the chromosomes to become more manageable and prevents them from becoming entangled during cell division.
- Nuclear envelope disappears: As prophase progresses, the nuclear envelope, which surrounds the nucleus, begins to break down and eventually disappears. This disintegration is critical for allowing the spindle apparatus to access the chromosomes. Once the nuclear envelope is gone, the chromosomes are free to interact with the spindle fibers.
- Spindle fibers grow from the centrioles: The spindle apparatus, which is responsible for separating the chromosomes, begins to form during prophase. Spindle fibers extend from the centrioles (structures that organize microtubules) and connect to the kinetochores of the chromosomes. These fibers are crucial for the later stages of mitosis, as they will pull the sister chromatids apart during anaphase.
- Centrioles are pushed apart: The centrioles, which duplicate before mitosis, move to opposite poles of the cell. This separation is necessary to establish the bipolar structure of the spindle apparatus, enabling the equal distribution of chromosomes to the two daughter cells.
Not Applicable:
- Chromosomes migrate to opposite poles occurs during anaphase, not prophase. In this stage, the spindle fibers shorten, pulling the sister chromatids apart towards opposite poles of the cell.
Understanding these events during prophase is essential for comprehending how cells replicate and maintain genetic stability through mitosis.