1. Class Notes 5: Mitosis and the Cell Cycle
A story where two cells are created from one!

2. I. What is mitosis?
Mitosis is a form of cell division in body cells, resulting in two new cells that are exactly the same as the original.
Meiosis is another form of cell division that creates sex cells.

3. II. Major “characters” in the cell cycle
A. Chromosomes: Contain DNA: the instructions to make proteins
Centromere
Nucleosome
DNA
Sister
Chromatids

4. B. Centrioles: made of microtubules

5. C. Spindle: forms between the centrioles to pull chromatids apart.

6. III. Interphase The cell cycle has 3 phases: 1.interphase 2. Mitosis
3. Cytokinesis
B. During interphase,
the longest phase, the cell
grows, produces proteins
and DNA replicates
(copies).

7. IV: Mitosis A. : PROPHASE
Chromosomes become visible.
Nuclear envelope disappears.
Spindle forms between centrioles.

8. B. Phase 2: METAPHASE
Chromosomes line up, creating a plate that splits the cell in half.
Spindles move to opposite sides of the plate

9. C. Phase 3: ANAPHASE
Chromosomes are split into chromatids at the centromere.
Chromatids are pulled into two separate groups towards opposite sides of the cell.

10. D. Phase 4: TELOPHASE Spindle breaks down. Chromosomes unwind
Two nuclear envelopes
form, one around
each cluster.

11. V. Cytokinesis: When 1 cell becomes 2
A. Animal Cells: The plasma membrane simply pinches in to create two new cells.

12. B. Plants: Form a “cell plate” to divide the cytoplasm between the two new forming cells. The plate will later become the new cell wall.

13. Summary What are the parts of the cell cycle?
What are the phases of mitosis?