1. Ch 5 The Cell Cycle

2. Cell Growth Limits to Cell Growth –Why do cells divide? The larger a cell gets: The more demands the cell puts on the DNA Exchanging material becomes difficult

3. Cell Growth Before a cell gets too big, it divides forming two identical “daughter cells”

4. Cell Division Every cell must copy its DNA before cell division begins. Each daughter cell then gets a copy of that DNA Mitosis- division of the cell nucleus. This happens in eukaryotes.

5. Chromosomes Genetic information is passed on by chromosomes Chromosomes are made of DNA Each chromosome is made of 2 sister chromatids and joined at the centromere.

6. Chromosomes When a cell is not in cell division, the DNA is found in the form of chromatin, not as chromosomes. DNA condenses to form chromosomes before cell division.

8. The Cell Cycle During the cell cycle a cell grows, replicates DNA and prepares for division, and divides to form two daughter cells, each of which begins the cycle again. Interphase – Cell is preparing for division (G 1, S, and G 2 phase) AFTER Interphase, Mitosis begins. The daughter cells then enter Interphase. **CYCLE**

9. Cell Cycle Animation Cell Cycle Animation p.2 Mitosis Video

10. Mitosis (PMAT) 1. Prophase Chromosomes condense and become visible Nucleus starts to break down Centrioles separate and get on opposite sides of the nucleus Centrioles help to organize the spindle fibers **Mitosis occurs in Somatic Cells (body cells) when new cells are needed.**

11. Mitosis (PMAT) 2. Metaphase Chromosomes line up across the center of the cell

12. Mitosis (PMAT) 3. Anaphase The centromeres that holds the chromatids together split The spindle helps pull the pair of chromosomes apart

13. Mitosis (PMAT) 4. Telophase Chromosomes gather at opposite ends of the cell Two new nuclear envelopes form

14. Cytokinesis Division of the cytoplasm The animal cell pinches in half to become two identical daughter cells In a plant cell the cell wall cannot be pinched so instead it builds a cell plate between the two nuclei

15. Mitosis

16. Uncontrolled Cell Growth Cancerous tumors are caused because cancer cells do not respond to the signals that regulate the growth of most cells.