1. Chapter 6

2. A repeating cycle of cell growth and division Why do cells reproduce?

3. Interphase This is the longest part of the cell cycle and is divided into three parts: G1 S G2

4. G1 (the first growth phase) – the cell graows rapidly in this phase and carries out its’ routine functions

5. S (synthesis phase) – in this phase, the DNA is copied Why? At the end of this phase, each chromosome consist of 2 chromatids Why?

6. G2 (second growth phase) – in this phase, microtubules form in preparation of the actual division process Microtubules will help move the chromosomes during cell division

7. This is the second part of the cell cycle and This is where the cell actually divides. Think of it like cloning – the process ends up with two identical cells

8. This is the last part of the cell cycle and involves the cytoplasm dividing

9. How does a cell know when to divide? When not to divide? When to slow down ? There are several “checkpoints” that let the cell know what to do

10. If conditions are favorable for cell division (the cell is healthy, large enough), the cell will start the division process. If not, the cycle stops at the G1 stage. Some nerve cells and muscle cells stay in this G1 stage forever… (think brain cells!)

11. At this point the DNA has been copied, right? If the DNA looks good, mitosis will begin. If not, the cycle ends.

12.  After mitosis is complete, the cell will go back into the g1 stage (growth)

13. Uncontrolled growth of cells The gene for regulating cell growth and division is mutated Questions: What is a tumor suppressing gene? What are the three types?

14. 1. Read page 127 : Cancer 2. Read page 128-132 to understand the details of Mitosis 3. Answer #’s 1-12 on page 134 4. Illustrate the stages of mitosis on a large poster board. Describe all the steps in detail. Make your drawings colorful, and make sure your illustration is labeled. These will be due Tuesday November 29th