Components of the Cell Cycle and Interphase, Mitosis components

Cell Cycle

Interphase

The cell is engaged in metabolic activity and performing its prepare for mitosis. Chromosomes are not clearly discerned in the nucleus, although a dark spot called the nucleolus may be visible. The cell may contain a pair of centroids (or microtubule organizing centers in plants) both which are organizational sites for microtubules.

G1 phase. Metabolic changes prepared the cell for division. At a certain point-the restriction point-the cell is committed to division and moves into the S phase.

S phase.DNA synthesis replicates the genetic material. Each chromosomes now consists of two

sister chromatids.

G2 phase. Metabolic changes assemble the cytoplasmic materials necessary for mitosis and cytokinesis this process is also known as interphase.

M phase. A nuclear division(mitosis)followed by a cell division(cytokinesis).



Mitosis: After preparation is complete, the cell

enter the 4-phased mitosis, Phophase, Prometaphase,

 Metaphase, Anaphase, and Telophase.  




Phophase

Chromatin in the nucleus begin to condense and becomes visible in the

light microscope as chromosomes. The nucleolus disappears. Centroles

begin moving to opposite ends of the cell and fiber extend from to the centroids.

Some fibers cross the cell to form the mitotic spindle.

Prometaphase

The nuclear membrane dissolves, making the beginning of the prometaphase.
proteins attach to the centromeres creating the kinetochores. Microtubules attach to the kinetochores and the chromosomes begin moving.

Metaphase

Sprindle fibers align the chromosomes along the middle of the cell nucleus.

This line is referred to as the metephase plate. This organization helps to ensure

that in the next phase, when the chromosomes are separated, each new nucleus will

receive one copy of each chromosome.

Anaphase

The paired chromosomes separated at the kinetochores and move to opposite sides of the cell. Motion results from a combination of kinetochores movement along the spindle microtubules and through the physical interaction of polar microtubules.




Telophase

Chromatids arrive at opposite poles of the cell, and new membranes form
around the daughter nuclei. The chromosomes disperse and no longer visible under the light microscope. The spindle fiber disperse, and kytokinesis or the partionig of the cell may also begin under this stage.

Cytokinesis

In animal cell cytokinesis results when a fiber ring composed of protein

called acting around the center of the cell contracts pinching the cell in two

daughter cells, each with one nucleus. In plant cells, the rigid wall requires

that a cell plate by synthesized between the two daughter cells.