1. Mitosis notes outline Why cells divide 1. DNA G1, S, G2 2. Diffusion
3. SA/volume ratio
4. repair
Cell division
A. Chromatin vs. chromosome
(picture and parts)
B. Stages (include pictures
1. interphase
G1, S, G2
2. mitosis
prophase
metaphase
anaphase
telophase
3. cytokinesis
animal vs. plant cell
END RESULT=

2. *Living things grow because they produce more cells.
Cell Growth
*Living things grow because they produce more cells.
*Rather than grow indefinitely, cells divide into new cells because it is more efficient for the cell.
WHY???

3. Factors that limit cell growth:
1. amount of DNA:
*cells remain small so DNA can meet all of the cell’s needs
2. exchange of materials through the cell membrane
ex. water, food, oxygen, waste products

4. surface area to volume ratio: surface area = 6(length x width)
volume = (length x width x height)
ratio = surface area
volume
*cells need high surface area for small volume for materials to easily enter/exit the cell
*volume increases faster than surface area thus decreasing the ratio and causing problems for the cell

6. cell division: process by which a cell divides into two new daughter cells
*done before a cell becomes too large so the cell is more efficient.
Solves problems mentioned: each cell gets DNA, reduces volume
Also used to repair and replace old cells

7. Cell Division
*Cells must copy their genetic information before cell division to ensure daughter cells have a complete copy.
Where is genetic info. (DNA) found in a cell? in nucleus packaged as chromosomes (usually exists as chromatin)

8. *all cells have a specific number ex. humans—46 carrots—18
Chromosomes:
*all cells have a specific number
ex. humans—46
carrots—18
fruit flies—8
*before division, chromosomes are replicated (an exact copy is made)
sister chromatids: two identical halves of chromosome
Centromere: holds sister chromatids together
Sister
chromatids
Centromere

9. Duplicated chromosome
Chromosomes
Sister
chromatids
Unduplicated
Chromosome
Duplicated chromosome

10. cell cycle: series of events that cells go through as they grow and divide
Stages of cell cycle:
1. interphase: period of growth
2. mitosis: division of cell nucleus
3. cytokinesis: division of cytoplasm

12. Cell Cycle Events:
I. Interphase:> 75% of time spent here, normal cell activities occur
3 phases:
1. G1: cell grows, synthesizes proteins and organelles
2. S: DNA (chromosomes) replicated
3. G2: organelles needed for division
are produced

14. II. Mitosis
4 phases:
1. prophase:
*longest phase of mitosis
*chromosomes become visible
*spindle fibers develop
*nucleolus disappears
*nuclear envelope breaks down

16. 2. metaphase:
*chromosomes line up in the middle (equator) of cell

18. 3. anaphase:
*centromere splits
* shortest phase of mitosis
*sister chromatids separate (become individual chromosomes) and move
apart

20. 4. telophase:
*chromosomes uncoil into chromatin
*nuclear envelope re-forms around
chromatin
*spindle disappears (break apart)
*nucleolus becomes visible
*opposite of prophase

22. III. Cytokinesis= division of cytoplasm
*occurs at the same time as telophase
animal cells: cell membrane is drawn inward until the cytoplasm is pinched into two nearly equal cells

23. plant cells: cell plate develops into a separating membrane; cell wall appears along cell plate

24. End result of Cell Cycle
Two new daughter cells that are genetically identical to each other and the parent cell.

25. Mitosis
Prophase Metaphase Anaphase Telophase

26. Section 8.2 Summary – pages 201 - 210
Results of Mitosis
Click image to view movie.
Section 8.2 Summary – pages