1. Ms. Mele Grade 8 Life Science
The Cell Cycle
Ms. Mele Grade 8
Life Science

2. Watson video

4. Three stages of the cell cycle
Interphase
Mitosis
Cytokinesis

5. Rat epithelial cell

6. Stage 1: Interphase
Cell grows to its mature size
Makes a copy of its DNA
Prepares to divide into two cells.

7. Stage 2: Mitosis- when the cell’s nucleus divides into two new nuclei.
Prophase
Metaphase
Anaphase
Telophase

8. Prophase The chromatin condenses to form rodlike chromosomes.
Each chromosome has 2 rods
The identical rods are called chromatids.
Spindle fibers form a bridge between the ends of the cell.
The nuclear membrane breaks down.

9. chromatin
duplicated
chromosome

12. Metaphase The chromosomes line up across the center of the cell
Each chromosome attaches to a spindle fiber at its centromere, which holds the chromatids.
Chromatids are the identical rod of a chromosome.

13. Anaphase The centromeres split Two chromatids separate
One chromatid moves along the spindle fiber to one end of the cell
The other chromatid moves to the opposite end
The cell becomes stretched out as the opposite ends pull apart

15. Telophase
The chromosomes begin to stretch out and lose their rodlike appearance
This occurs in the two regions at the ends of the cell
A new nuclear membrane forms around each region of chromosomes

17. ANIMAL CELL CENTROSOME:

18. Cytokinesis The cell membrane pinches in around the middle of the cell
Each daughter cell ends up with the same number of identical chromosomes

19. Length of the Cell Cycle
Depends on the type of cell
A human liver cell completes the cycle in 22 hours
Each cycle also varies from cell to cell
Human brain cells never divide, they stay at interphase