1. HOMEOSTASIS IN CELLS pp

2. Why are cells so small?
How does a cell maintain homeostasis?

3. CELL REVIEW Cell membrane Genetic material (DNA)
Ribosomes: make proteins
Cytoplasm: surrounds the cell’s organelles

4. CELL TYPES
Prokaryotes: oldest living cells that lack membrane-bound organelles, are unicellular, and very small in size
Eukaryotes: contain a membrane-bound nucleus and organelles and much bigger than prokaryotic cells

5. Prokaryotic Cell

7. Animal Cell

8. Plant Cell

9. HOMEOSTASIS
Organisms have mechanisms that keep conditions within a specific range, despite changes in the environment
Changes in the environment for a single cell can include changes in temperature, water, concentration of solutes in surrounding environment, and build up of wastes

13. Cell membrane
Selectively permeable (semi-permeable): controls what comes into and out of the cell
Made of phospholipids that form a lipid bilayer

14. Fluid mosaic model: cell membrane behaves more like a fluid than solid and the layers are always moving

16. The cell membrane has many different macromolecules imbedded within the phospholipids
- Carbohydrates and lipids can be use for cell-to- cell communication or as cell markers
- Peripheral proteins are attached to the surface of the cell membrane
- Integral proteins are embedded in the bilayer and are often channel proteins.
- Cholesterol makes the membrane more fluid and less rigid at colder temperatures

17. How does the cell membrane maintain homeostasis in a cell?