1. Mitosis and Interphase
The Cell Cycle
Mitosis and Interphase

2. All living things.. ..begin life as a single fertilized cell.
Humans begin as a cell that results from the combination of an OVUM or human egg cell and a SPERM cell... Together they form an EMBRYO.

3. The embryo… ….then begins to divide into exact duplicate “stem cells”.
these first cells will be the basis for all future cells in the human body.
---->note the number of cells at each step

4. This little batch of cells…
…will not stay the same. Cells specialize and take on different jobs.
>at 5-6 weeks the embryo has animal-like features including a fully functional heart.

5. How does this work? Let’s go back to this little batch of 8 cells…
We will now look at cells when they are dividing…and when they aren’t!

6. The Cell Cycle
The steps that prepare and lead up to cell division.

7. Interphase The time between cell division Cell is doing its job
Genetic material is all unraveled as chromatin
The time between cell division
Cell is doing its job
DNA duplicates-chromosomes make exact copies of themselves
Nuclear membrane
clearly in place

8. Mitosis Cell divides to form two identical cells
Can look at 7 different stages:
Interphase
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
Cytokinesis

9. Prophase DNA condenses to form distinct chromosomes
Nuclear membrane begins to break down.
Centrioles appear from centrosomes (microtubule organizing center) and begin to form spindle fibers.

10. Prometaphase Nuclear membrane breaks down.
Proteins attach to centromeres to form kinetichores (eventually will attach to spindle fibers)
Chromosomes move to center of cell along microtubules..

11. Metaphase Chromosomes line up in the middle (equator) of the cell
Spindle fibers attach

12. Anaphase
Chromosomes separate and move toward the opposite ends of the cell (poles)

13. Telophase Chromosomes reach the poles New nuclear membrane forms
Chromosomes unwind to become thread-like chromatin again

14. Cytokinesis (End of Telophase)
The cytoplasm is evenly divided
New cell membrane forms in animal cells
New cell wall is built across for plant cells

15. VIDEOS Drosophila Embryo - http://www.youtube.com/watch?v=m73i1Zk8EA0
Blood Lily -

16. Recap

18. Interphase/early prophase

19. Prophase

20. Metaphase

21. Anaphase

22. Telophase

23. OK, fine…but who really
cares about MITOSIS and cell division???

24. Nerve cells… …remain in INTERPHASE for long periods of time.
They go through mitosis about once every 75 years.
So?…

25. Damage to these cells…
…is often very serious.

26. Some damage is not permanent
Gloria Estefan was involved in a tragic tour bus accident.
Surgeons were able to repair her nearly severed spinal chord.
She recently donated $1,000,000 for spinal cord injury research---->

27. Cancer cells… …behave much differently than nerve cells.
…spend very little time in interphase and go through mitosis uncontrollably.
What does that mean?
Approx. 1/10,000 of your cells are cancerous but your immune system usually kill them rapidly—