1. Warm-up: Why do cells divide? HW: Enter Date Aim: MITOSIS
Regents Biology

2. Where it all began…
You started as a cell smaller than a period at the end of a sentence…
Regents Biology

3. Getting from there to here…
Going from egg to baby….
the original fertilized egg has to divide…
and divide…
Regents Biology

4. Why do cells divide… for reproduction for growth & development
one celled organisms (clones)
for growth & development
from fertilized egg to multi-celled organism
for repair
replace cells that die from normal wear & tear or from injury
amoeba
starfish
Unicellular organisms
Cell division = reproduction
Reproduces entire organism& increase population
Multicellular organisms
Cell division provides for growth & development in a multicellular organism that begins as a fertilized egg
Also use cell division to repair & renew cells that die from normal wear & tear or accidents
Regents Biology

5. Regents Biology

6. Dividing cells… What has to be copied DNA organelles cell membrane
lots of other molecules
enzymes
plant cell
animal cell
Regents Biology

7. What is Mitosis? Mitosis is the division of the cell’s nucleus.
This process makes two identical cells.

8. Steps of Mitosis The steps involved in mitosis include: 1. Interphase
2. Prophase
3. Metaphase
4. Anaphase
5. Telophase
6. Cyntokinesis

9. http://www.ehow.com/vi deo_4984775_what- interphase.html
During interphase, the cell grows and prepares for cell division.
It is divided into three phases:
1. G1 phase
2. S phase
3. G2 phase

10. G1 Phase During this phase, cells do most of their growing.
They increase in size and synthesize new proteins and organelles.

11. S Phase
During this phase, chromosomes are replicated and the synthesis of DNA molecules takes place.

12. G2 Phase
During this phase, all the rest of the organelles and molecules needed for division are produced.
This is a very short phase.
Once this phase is complete, the cell enters the M phase. (M stands for Mitosis)

13. Mitosis: Dividing DNA & cells
Stage 1: cell copies DNA
Copy DNA!
DNA
cell
nucleus
(interphase)
Regents Biology

14. Mitosis: Dividing DNA & cells
Stage 2: DNA winds into chromosomes
DNA is wound up into chromosomes to keep it organized
duplicated chromosomes
Wind up!
cell
nucleus
(prophase)
Regents Biology

15. Regents Biology

16. Mitosis: Dividing DNA & cells
Stage 3: Chromosomes line up
chromosomes line up in middle
attached to protein “cables” that will help them move
Line up!
duplicated chromosomes
lined up in middle of cell
(metaphase)
Regents Biology

17. Mitosis: Dividing DNA & cells
Stage 4: Chromosomes separate
chromosomes split, separating pairs
start moving to opposite ends
Separate!
chromosomes split & move to opposite ends
(anaphase)
Regents Biology

18. Mitosis: Dividing DNA & cells
Stage 5: Cell starts to divide
cells start to divide
nucleus forms again
Divide!
(telophase)
Regents Biology

19. Mitosis: Dividing DNA & cells
Stage 6: DNA unwinds again
cells separate
now they can do their every day jobs
Bye Bye!
(cytokinesis)
Regents Biology

20. Cytokinesis in Plants
In plant cells, the only difference is that a cell plate forms between the two cells.
This cell plate develops into a cell membrane and the cells eventually split.

21. New “daughter” cells Get 2 exact copies of original cells same DNA
“clones”
Regents Biology

22. Mitosis in whitefish embryo
Regents Biology

23. Mitosis in plant cell
Regents Biology

24. Overview of mitosis Copy DNA Wind Up Bye-Bye! Line Up Separate Divide
Regents Biology
Line Up
Separate
Divide