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 threestages.

Interphase:

• 1. G1 Stage: period of rapid growth

• This stage last longer than other stages.

• A cell grows and carries out its normal cell functions.

Interphase:

• 2. S Stage: a cell continues to growand 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 mitoticphase.

Mitosis:

• The nucleus and its content divide

• Cell 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 identicalto 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.