Mitosis is defined as the division of the nucleus. In animal cells, consists of 5 major phases – prophase, prometaphase, metaphase, anaphase and telophase. Cytokinesis occurs immediately following telophase, the last phase of mitosis and is the division of the cytoplasm. Mitosis and cytokinesis are phases when the cell is actively dividing and these stages last for a very short time compared to interphase. For most of a cell’s life, it is in interphase, which is a phase that prepares the cell for mitosis. However, the length of the entire cell cycle and the length of time a cell spends in each part of the cycle depends on the type of cell.
Interphase is a relatively long phase and is composed of three stages …show more content…
The chromosomes condense and become so compact that they are able to be seen with light microscope. This marks the beginning of prophase. Each chromosome contains two identical copies called sister chromatids. The sister chromatids are attached at a central point called a centromere. The second key event in prophase is the assembly of the mitotic spindle apparatus. In animal cells, two pairs of organelles called centrioles move to opposite poles of the cells forming the fibers of the spindle apparatus between them as they move. The spindle apparatus controls the orderly separation of the duplicated chromosomes into two equal …show more content…
The attachment of the spindle fibers to the kinetochores of the chromosomes marks the beginning of metaphase. Kinetochores are attachment points on either side of the centromere. In this way, spindle fibers attach to each sister chromatid. Chromosomes move to the center of the cell. Each chromosome is positioned along a central plane with its centromere in the middle and each sister chromatid on either side of the plane.
Anaphase is the shortest of the four phases and has three key events. The division of the sister chromatids at the centromeres marks the beginning of anaphase. Spindle fibers shorten, drawing each of the sister chromatids, now known as chromosomes, to opposite poles of the cell. Some of the spindle fibers lengthen which elongates the cell.
Telophase is the final phase of mitosis. Three important events occur during telophase. All three of the events happen simultaneously. The mitotic spindle apparatus is disassembled. A nuclear envelope reforms around the chromosomes. The chromosomes unwind from the condensed form. At the end of telophase, there are an equal amount of chromosomes at opposite poles of the cell.