Cell Division Notes

Cell Cycle Most cells in an organism go through a cycle of growth, development, and division called the cell cycle.

Interphase: Is the period during the cell cycle of a cell’s growth and development. A cell spends most of its life in interphase. Divided into three stages.

Interphase: 1. G1 Stage: period of rapid growth This stage lasts longer than other stages. A cell grows and carries out its normal cell functions.

Interphase: 2. S Stage: a cell continues to grow and copies its DNA. There are now two identical strands of DNA Sister chromatids: two identical chromosomes Centromere: what holds that sister chromatids together

Interphase: 3. G2 Stage: the cell is getting ready for mitosis. The cell stores energy that will be used during the mitotic phase.

Mitosis: The nucleus and its content divide Cells divide to increase their numbers

Phases of Mitosis 1. Prophase: Copied DNA condenses into chromosomes The nucleolus disappears, and the nuclear membrane breaks down. Spindle fibers begin to form.

Phases of Mitosis 2. Metaphase: Chromosomes line up in a single file at the center of the cell.

Phases of Mitosis 3. Anaphase: Sister chromatids separate Spindle fibers begin to shorten, pulling chromatids toward opposite sides of the cell. The cell begins to lengthen.

Phases of Mitosis 4. Telophase: A nuclear membrane forms around the chromatin. Chromosomes begin to unwind. Spindle fibers begin to break down. Two identical cells form.

Cell Division Cytokinesis: the cytoplasm and its contents divide. Daughter cells: are the two new cells that result from mitosis and cytokinesis.

Results of Cell Division: Results in two cells Daughter cells are genetically identical to each other. Allows multicellular organisms to grow and develop. Replaces cells that worn out or are damaged. It is also critical for repairing damages. Example: bone breaks- cell division produces new bone cells that patch the broken pieces.