Chapter 6. A repeating cycle of cell growth and division Why do cells reproduce?
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Transcript of Chapter 6. A repeating cycle of cell growth and division Why do cells reproduce?
The Cell CycleChapter 6
What is it?
A repeating cycle of cell growth and division
Why do cells reproduce?
The Cell Cycle consist of three parts:
Interphase
This is the longest part of the cell cycle and is divided into three parts:
G1SG2
Interphase (part 1)
G1 (the first growth phase) – the cell graows rapidly in this phase and carries out its’ routine functions
Interphase (part 2)
S (synthesis phase) – in this phase, the DNA is copied
Why?
At the end of this phase, each chromosome consist of 2 chromatids
Why?
Interphase (part 3)
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
Mitosis
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
Cytokinesis
This is the last part of the cell cycle and involves the cytoplasm dividing
Cell Cycle Control
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
G1 checkpoint
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!)
G2 checkpoint
At this point the DNA has been copied, right? If the DNA looks good, mitosis will begin. If not, the cycle ends.
Mitosis checkpoint
After mitosis is complete, the cell will go back into the g1 stage (growth)
Cancer
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?
Your job
1. Read page 127 : Cancer2. Read page 128-132 to understand
the details of Mitosis3. Answer #’s 1-12 on page 1344. 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