Cell DivisionChapter 2 lesson 3

Objective: Understanding the functions of cell divisionWhy do cells divide?

Growth of an organismRepairing damaged structures ex. If you skin your knee

Reproduction- especially for single celled organisms such asamoebas

The Cell Cycle

Occurs in three stagesInvolves cell growth, preparing for division, and then division into two new cells

The two new cells are called daughter cellsEach daughter cell then begins the cell cycle again

Three main stages: Interphase, Mitosis, Cytokinesis

Stage one: InterphaseThe 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 replicationDNA gets packaged into chromosomesEach cell created will contain an identical sets of chromosomes

Cells produce structures that will help with cell division

Stage 2: MitosisThe cell nuclei divides into two new nuclei and one set

of DNA goes to the daughter cellsFour 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 cellAnimal Cells- the cell membrane squeezes together

around the middle of the cellPlant Cells- cell plates form across the middle of the

cell, new cell walls develop