2. Bacteria developed specialized membranes that could perform metabolic functions Photosynthesis and cellular respiration Oxygen revolution (2.7-2.2 billion years ago) Led to the rise of eukaryotes

3. 2.1 billion years ago Endosymbiosis and Genetic Annealing Resulted in cells with organelles Result – Bigger cells with membrane bound organelles

4. Selectively Permeable Phospholipid bilayer Held together by hydrophobic interactions 1 2 Function and Structure

5. Fluid structure with proteins embedded and/or attached Allows for movement within and across

7. Integral Proteins embedded in the membrane Peripheral Proteins loosely bound to the surface

8. Transport Enzymatic activity Signal Transduction Cell-cell recognition Important in embryo development Glycolipids and glycoproteins Ex. blood type determination (glyco-proteins)

9. Intercellular joining Attachment to cytoskeleton Give cell shape

10. Hydrophobic molecules (CO₂, O₂) move easily across Polar molecules (glucose, sugars, and water) pass slowly across

11. Passive Transport No input of energy Result of a concentration gradient Examples: diffusion and osmosis and facilitated diffusion 5

12. Active Transport Uses energy and transport proteins Moves solutes against concentration gradients. Example: Sodium Potassium Pump Maintains membrane potential

13. 9

14. Exocytosis: Vesicles fuses with PM and release contents Examples: excreting insulin, nerve cell releasing neurotransmitters. 7

15. PM pinches in and forms a vesicle Phagocytosis = cell eating Pinocytosis = cell drinking 8