Mitosis and the Cell Cycle!

The Cell Cycle A living organism has a life cycle. A life cycle begins with the organism’s formation, is followed by growth and development, and finally ends in death. Individual cells also have life cycles.

The Cell Cycle The sequence of growth and division of a cell. 95% of cell cycle in interphase 5% of cell cycle in mitosis

Interphase Before a cell divides, a copy of the hereditary material must be made so that each of the two new cells will get a complete copy. Each cell needs a complete set of hereditary material to carry out life functions.

Interphase After interphase, cell division begins. The nucleus divides, and then cytoplasm separates to form two new cells.

Mitosis Mitosis (mi TOH sus) is the process in which the nucleus divides, forming two identical nuclei. Each new nucleus also is identical to the original nucleus. Mitosis is described as a series of phases, or steps. The steps of mitosis in order are named prophase, metaphase, anaphase, and telophase.

Prophase Nuclear envelope disappears Chromosomes condense – can see sister chromatids Spindle forms

Metaphase Chromosomes move to the equator of spindle Each chromatid is attached to spindle with centromere

Anaphase Centromeres split Sister chromatids are pulled apart to opposite poles of the cell Each chromatid is now a separate chromosome

Telophase Spindle fibers start to disappear Chromosomes begin to uncoil New nucleus forms

Cytokinesis Cytoplasm divides Two new daughter cells are now separate

Results of Mitosis Mitosis is the division of the nucleus, and it produces two new nuclei that are identical to each other and the original nucleus. 46 chromosomes in all body cells EXCEPT in sperm and egg cells.

Results of Mitosis Cell division allows growth and replaces worn out or damaged cells. If you cut yourself, the wound heals because cell division replaces damaged cells. Another way some organisms use cell division is to produce new organisms.

Class Activity Mitosis “Comic” Strip Create an illustrated guide to the steps of Mitosis