Cell Division Chapter 2 lesson 3

Objective: Understanding the functions of cell division  Why do cells divide?  Growth of an organism  Repairing damaged structures ex. If you skin your knee  Reproduction- especially for single celled organisms such as  amoebas

The Cell Cycle  Occurs in three stages  Involves cell growth, preparing for division, and then division into two new cells  The two new cells are called daughter cells  Each daughter cell then begins the cell cycle again  Three main stages: Interphase, Mitosis, Cytokinesis

Stage one: Interphase  The cell grows to full size and produces the organelles it needs  The cell then makes an exact copy of DNA in the nucleus. This is called replication  DNA gets packaged into chromosomes  Each cell created will contain an identical sets of chromosomes  Cells produce structures that will help with cell division

Stage 2: Mitosis  The cell nuclei divides into two new nuclei and one set of DNA goes to the daughter cells  Four stages  Prophase- nuclear envelope breaks down, spindle fibers form and connect at opposite sides, chromosomes condense.  Metaphase-chromosomes, attached to spindle fibers, line up in the center of the cell  Anaphase- chromatids split and move to opposite sides of the cell  Telophase- spindle fibers disappear, nuclei are forming, cell is pinched in the middle

Stage three: Cytokinesis Completes process of cell division Each Daughter cell has the same number of chromosomes and is an exact copy of the parent cell  Animal Cells- the cell membrane squeezes together around the middle of the cell  Plant Cells- cell plates form across the middle of the cell, new cell walls develop