Download Phases of Mitosis NOTES

Phases of Mitosis NOTES
What is mitosis?
–A part of the cell cycle of cell division as it occurs in all cells of the body except the sex cells
(eggs and sperm, also known as gametes)
-in mitotic cell division one “parent cell” divides to give two genetically identical “daughter cells”
-thus, after mitotic cell division each daughter cell has the same number of chromosomes as the
parent cell
Chromosomes and mitosis
The PARENT CELL contains matched pairs of chromosomes = 2 copies of each chromosome (2n).
Following DNA replication, the parent cell contains a total of 4 copies of each chromosome (4n).
The replicated chromosomes remain in attached pairs called “SISTER CHROMATIDS”
At the midpoint of mitosis, known as METAPHASE the SISTER CHROMATIDS are aligned and
held in position by the mitotic apparatus (also known as the mitotic spindle).
During ANAPHASE the SISTER CHROMATIDS separate and are pulled to opposite ends of the
cell.
During CYTOKINESIS the cytoplasm of the parent cell divides to create two “DAUGHTER
CELLS”
A nuclear membrane re-forms around each set of chromosomes.
Each daughter cell contains matched pairs of chromosomes = 2 copies of each chromosome (2n).
REMEMBER:The daughter cells of mitosis are genetically identical to one another, and to the parent cell.
The Phases of the Mitotic Cell Cycle
1. Interphase: DNA replication occurs and the centrosome is duplicated; the chromosomes appear as thread-like coils called “chromatin”
2. Prophase: the chromatin condenses into dense chromosomes visible as attached pairs called “sister chromatids;” the centrosomes begin
to move to opposite sides of the cell and to form the mitotic spindle
3. Prometaphase: The nuclear envelope breaks down and disappears, spindle fibers reach the chromosomes and begin to attach to the
kinetochores at the centromeres, forces exerted by the attached spindle fibers begin moving the chromosomes to the center (midline)
of the cell
4. Metaphase: the mitotic spindle is fully formed; the spindle fibers are fully attached to the kinetochores at the centromeres of the
sister chromatids and have aligned the sister chromatids across the center (midline) of the cell
5. Anaphase: the sister chromatids separate and are pulled to opposite poles of the cell
6. Telophase: the nuclear envelopes begin to reform and the chromosomes decondense to appear once again as chromatin.
7. Cytokinesis: the cytoplasm divides to produce two genetically identical daughter cells, each with its own nucleus.