Essay by DanielleReneeJunior High, 9th gradeA, May 2005

download word file, 2 pages 4.3

Downloaded 41 times

The stages of the cell cycle is an ordered set of events rising in cell growth and division into two daughter cells. Non dividing cells are not considered to be in the cell cycle. Mitosis is further divided into 4 phases, which you will read about later on. Interphase is when the cell is in metabolic activity and performing its prepare for mitosis.Chromosomes are not clearly seeable in the nucleus, although a dark spot called the nucleolus is visible. The cell may hold a pair of centrioles.

Mitosis is a nuclear division plus cytokinesis, and produces two identical daughter cells during prophase, prometaphase, metaphase, anaphase, and telophase. Interphase is sometimes included in mitosis. Chromatin in the nucleus begins to condense and becomes visible in the light microscope as chromosomes. The nucleolus disappears. Centrioles begin moving to opposite ends of the cell and fibers extend from the centromeres. Some fibers cross the cell to form the mitotic spindle.

Prometaphase is when the nuclear membrane dissolves, marking the beginning of prometaphase. Proteins attach to the centromeres creating the kinetochores. Microtubules attach at the kinetochores and the chromosomes begin moving.

Metaphase spindle fibers align the chromosomes along the middle of the cell nucleus. This line is referred to as the metaphase 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 is when paired chromosomes separate at the kinetochores and move to opposite sides of the cell. Motion results from a combination of kinetochore movement along the spindle microtubules and through the physical interaction of polar microtubules.

Telophase is when Chromatids arrive at opposite poles of cell, and new membranes form around the daughter nuclei. The chromosomes disperse and are no longer visible under the...

Télécharger le torrent du film; All Inclusive | Todos Estão Mortos (Todos están muertos) 2014 | Gwilym Lee