How Cells Make More Cells The CELL CYCLE is the process by which cells divide to make new cells. There are three main stages to this cycle. They are: 1.Interphase 2.Mitosis (prophase, metaphase, anaphase, and telophase) 3.Cytokinesis

I. Interphase This part takes the longest amount of time of all of the stages of cell division. Here’s what’s going on: The cell grows- doubles in size, organelles get bigger or more of them are produced. The cell copies it’s DNA-This is called REPLICATION. Now there’re two sets. The cell prepares to divide- some structures needed for division are made.

II. Mitosis Mitosis is when the cell’s nucleus actually divides and each new cell (called daughter cells) gets a copy of the DNA. 1.Prophase: chromosomes (rod-shaped) form from chromatin, nuclear membrane breaks down, spindle fibers form.

2. Metaphase: Chromosomes line up across the middle of the cell. Spindle fibers attach to the chromosomes at the centromere (a structure that holds the chromatids together).

3. Anaphase The centromeres split. The two chromatids move toward opposite ends of the cell. The cell begins to stretch out.

4. Telophase Chromosomes start losing their rod-like shape and begin looking like chromatin again. The nuclear membrane begins to reform around the chromosomes.

III. Cytokinesis This is the stage in which the cell completes the formation of two new daughter cells. Animal Cells: New organelles are distributed. Cell membrane pinches around the middle into forming two new cells.

Plant Cells: This is a little different because plant cells have a cell wall. A cell plate forms between the two daughter cells and this forms a new cell membrane. New cell walls form around the cell membranes.

Timeframe for the cell cycle in a human liver cell I. Interphase: 21 hours –Growth: 9 hours –DNA Replication: 10 hours –Preparation for Division: 2 hours II. Mitosis –Prophase –Metaphase –Anaphase –Telophase III. Cytokinesis 1 hour TOTAL

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