1. Principles of Biology By Frank H. Osborne, Ph. D. Lab 9 - The Cell Cycle

2. The G 1, S and G 2 phases are all part of Interphase.

3. Interphase A. The G 1 Phase 1. The cell grows and doubles the number of cytoplasmic components. 2. The cell prepares for DNA synthesis. B. The S Phase 1. The cell synthesizes DNA. 2. Each chromosome develops a second chromatid.

4. C. The G 2 Phase 1. The cell completes activities required for cell division. 2. The cell prepares to divide.

5. Phases of Mitosis Interphase Prophase Anaphase Telophase Metaphase

6. Cell Division A. Mitosis 1. Mitosis is the division of the nucleus. 2. Phases of mitosis. a. Prophase i. This occurs first. (pro = pre) ii. The nuclear membrane disappears. iii. The nucleoli disappear. iv. The chromosomes shorten and thicken. v. The spindle forms.

7. Prophase

8. Spindle spinning wheel Spindle

9. b. Metaphase i. The chromosomes line up in the center (equator) of the spindle. ii. The centromere of each chromosome divides. iii. Each centromere is attached to a microtubule of the spindle.

10. c. Anaphase i. The chromosomes are pulled toward the poles of the spindle. ii. Each chromosome has one chromatid.

11. d. Telophase i. The chromosomes have arrived at the poles of the spindle. ii. The nuclear membrane is rebuilt iii. The nucleoli reappear.

12. Mitosis in a plant cell

13. B. Cytokinesis 1. Cytokinesis is a division of the cytoplasm. 2. Cytokinesis begins as telophase ends. Cells pinch hereCell plate

14. Cell Division C. Differences in cell division 1. Animal cells a. Animal cells need centrioles to help form the spindle. b. Animal cells pinch apart because they do not have cell walls.

15. Cell Division 2. Plant cells a. Plant cells can form a spindle without centrioles. b. Plant cells form a middle lamella during cytokinesis.

16. Cell Division D. Properties of cell division 1. There are two of each chromosome in each body cell. 2. Mitosis assures that each daughter cell has the same number of chromosomes as the mother cell. 3. Formation of reproductive cells is different.

17. The End Lab 9 The Cell Cycle