1. Mitosis: Cell Division
Why do cells divide?
they get too big
Replace damaged cells
Make new cells

2. DNA & Chromosomes
During normal time in the cells- DNa is found in the form of chromatin (long stringy)
During mitosis: chromatin wraps around proteins called histones to form chromosomes

3. Chromosome Structure
Each side called a chromatid, held together with a centromere

4. Cell Cycle Three parts: Interphase (G1, S, & G2)
Mitosis (nucleus divides)
Cytokinesis (cell splits)
Mitosis
cytokinesis
Interphase

5. Interphase
G1: Growth 1- cell grows to full size and produces new organelles
S phase: cell replicates DNA- makes an exact copy of the DNA in its nucleus
G2: growth 2- cell produces structures needed for division
Once G2 is complete it is time to divide

6. Mitosis Stage in which the nucleus divides into two daughter nuclei
Mitosis is divided into 4 phases

7. Stage 1: Prophase Nuclear envelope disappears
Chromatin coils up and forms chromosomes
Centrioles move to opposite sides of the cell
Centrioles make spindle fibers

8. Stage 2: Metaphase Chromosomes line up in the center of the cell
Each chromosome is attached to a spindle fiber at its centromere

9. Stage 3: Anaphase
Centromeres split, two chromatids separate- each chromatid becomes a new chromosome
Chromatids move to opposite ends of the cell
Cell stretches apart

10. Stage 4: Telophase Nuclear envelope begins to reappear
Chromosomes uncoil (chromatin)
Spindle fibers begin to break down and disappear
Centrioles move back to the nucleus

11. Cytokinesis Division of the cytoplasm Cell physically splits in two
In animal cells- cell membrane pinches down the middle
Plant cells- a cell plate grows in between the 2 new daughter cells

12. How Long?
Cell cycle length differs in all cells, however, human liver cells:
G1: 9 hours
S: 10 hours
G2: 2 hours
Mitosis & cytokinesis: 1 hour
Interphase: 21 hours