1. Bellwork 5.1 Describe the components of the cell theory.

2. Bellwork 5.1 Describe the components of the cell theory. All living organisms are composed of one or more cells. Cells are the smallest unit of living organisms. Cells arise only from previously existing cells

3. The Cell Cycle Chapter 5.1

4. Objectives 5.1 Discuss the size of a cell Discuss the primary stages of the cell cycle Discuss the stages of interphase

5. Cell Size 5.1 Cells are limited in size because of their ratio of surface to area volume. The plasma membrane is the surface As a cell increases in size volume increases faster than surface area

6. Cell Size 5.1 With too high of a ratio, cells Are unable to transport substances efficiently through the cell membrane and cytoskeleton Cannot communicate efficiently using signaling proteins.

7. 4 Phases of the Cell Cycle 5.1 G 1 – primary growth phase S – synthesis; DNA replicated G 2 – cell prepares to divide M – mitosis occurs

9. Interphase 5.1 Includes G 1, S and G 2 phases. During this time the genetic material remains as loosely packed chromatin fibers.

10. Interphase – G 1 Stage 5.1 Cells mature by making more cytoplasm and organelles. Cell carries on its normal metabolic activities.

11. Interphase - S Stage 5.1 DNA is replicated. Original DNA DNA Two identical copies of DNA

12. Interphase – G 2 Stage 5.1 Occurs after DNA has been copied. All cell structures needed for cell division are made (ex. Centrioles) Both organelles and proteins are synthesized.

13. Mitotic Phase 5.1 Split into Mitosis and Cytokinesis. Mitosis – chromatin compacts into chromosomes, which pair up as identical sister chromatids. Cytokinesis – phase which has the actual division of the cell. Produces two genetically identical daughter cells.

14. DNA Copied Cells Mature Cells prepare for Division Cell Divides into Identical cells Daughte r Cells

15. In Summary 5.1 Cell size is limited by the plasma membrane’s surface to volume ratio with the cytoplasm. The cell cycle is composed of a mitotic phase and interphase.