Cells

1. Cells • Day 1 – Diffusion, plasma membrane

2. Molecular Movement • Molecules are always in motion • Move in straight lines until collision • Dynamic equilibrium

3. Diffusion • High to low concentration • No energy required (passive transport)

4. Fluid Mosaic Model • Membrane molecules like a sheet of mosaic tiles, but fluid

6. Main component of plasma membrane Polar head - hydrophilic Non-polar tails - hydrophobic Phospholipid Molecules Head Tails

8. Lipid Bilayer • Inside and outside of cell primarily water • 2 layers of phospholipids face each other to form membrane (lipid bilayer)

9. Phospholipid Tails • Saturated and unsaturated to keep structure fluid • Animation

10. The Lipid Bilayer

11. Diffusion through the Bilayer • Small molecules (O2, CO2) • Other non-polars – alcohol, fat-soluble vitamins • Through the pores between polar heads Pores Top View of Polar Heads

12. Proteins • Embedded within the lipid bilayer • Surface only – peripheral proteins • Extend through membrane – integral proteins

13. Peripheral Protein Integral Protein

14. Integral vs. Peripheral • Integral – transport molecules across the plasma membrane • Peripheral - help create “identify” of the cell • Carbohydrate “dog tags” attached

15. Carbohydrates

16. Carbohydrates • Glycolipid – carb attached to phospholipid • Glycoprotein – carb attached to protein • Glycocalyx (“sugar coat”) – carbs and peripheral proteins on surface of cells

17. Glycocalyx

18. Cholesterol

19. Cholesterol • Between tails of the phospholipids • Prevents tails from tangling • It also stabilizes the membrane.