Notes: Ch. 12 part 1- Cell Division
• One of the major characteristics of a living thing is
.
• What does growth mean in terms of the cell? Bigger cells or more cells?
• Why more cells?
-if a cell gets too large, it wouldn’t be possible for it to get oxygen/nutrients in and wastes out by
diffusion
CELL DIVISION
• In simple terms: 1 cell divides into 2 new cells
• 3 main stages of the cell cycle:
1) Interphase:

2) Mitosis:

3) Cytokinesis:

Cell Cycle: (label circular chart)
• MITOSIS =
• Why is it important that the NUCLEUS divides?
• Chromosomes = tightly __________________________ (DNA);
consist of ______________________ (sister chromatids); which are
connected in the center by a __________________________
**a human cell entering mitosis contains:
(This is its DIPLOID number)
How Does Chromatin Coil so Tightly?
• Chromatin wraps around 8 histone proteins
•
A second type of histone (H1) holds the nucleosome “beads” together to increase compaction further
Next: the stages of MITOSIS!
Mitosis is one, continuous event, but it can be described as happening in 5 phases:
1)
2)
3)
4)
5)
(followed by cytokinesis!)
**Remember, the cell is coming out of INTERPHASE!!!
NOTES: Phases of MITOSIS (division of the NUCLEUS)
Phase
Events

Prophase


Prometaphase


Metaphase

Sketch
Phase
Events

Anaphase



Telophase


 in animal cells:
Cytokinesis
 in plant cells:
Then the cell returns to Interphase…and the cell cycle continues!
Sketch