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 fertilized OVUM or human egg cell.

3. The egg cell …
….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 ovum has divided into 8 stem cells

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

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

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

7. Mitosis Prophase Metaphase Anaphase Telophase
Cell divides to form two new cells
Can look at four different stages
Prophase
Metaphase
Anaphase
Telophase

8. Prophase DNA condenses to form distinct chromosomes
Nuclear membrane disappears

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

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

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

12. 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

13. OK, fine…but who really
cares about MITOSIS and diving cells???

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

15. Damage to these cells…
is often
VERY
serious.

16. 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.

17. Cancer cells… …behave much differently than nerve cells.
…spend very little time in interphase and go through mitosis uncontrollably.
Approx. 1/10,000 of your cells are cancerous-the good news-your defense cells usually kill them fast-->