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.