Mitosis Flashcards
The period of a cell’s life when it carries out its normal metabolic activities and grows. During this phase, the DNA-containing material is in the form of chromatin. The nuclear envelope and one or more nucleoli are intact and visible.
Interphase
The chromatin condenses, forming barlike chromosomes that are visible with a light microscope. Each duplicated chromosome appears as identical threads, now called sister chromatids, held together at a small, constricted region called a centromere. (After the chromatids separate, each is considered a new chromosome.)
Early Prophase
While the centrosomes are still moving apart, the nuclear envelope fragments, allowing the spindle to interact with the chromosomes. Some of the growing spindle microtubules attach to kinetochores, special protein structures at each chromosome’s centromere. Such microtubules are called kinetochore microtubules.
Late Prophase
This is the second phase of mitosis. The two centrosomes are at opposite poles of the cell. The chromosomes cluster at the middle of the cell, with their centromeres precisely aligned at the equator of the spindle. This imaginary place midway between the poles is called the metaphase plate.
Metaphase (Middle)
This is the third and shortest phase of mitosis. Begins abruptly as the centromeres of the chromosomes split simultaneously. Each chromatid now becomes a chromosome in its own right.
Anaphase (Apart)
Begins as soon as chromosomal movement stops. This final phase is like prophase in reverse. The identical sets of chromosomes at the opposite poles of the cell uncoil and resume their threadlike chromatin form.
Telophase (Two)
As mitosis draws to a close, this stage completes the division of the cell into two identical daughter cells. Occurs as a contractile ring of actin microfilaments forms the cleavage furrow and pinches the cell apart. Begins in late anaphase.
Cytokinesis
