The Plasma Membrane

1. The Plasma Membrane Section 7.2

2. Ticket in the Door • What are the 3 principles of cell theory? • What is one main difference between prokaryotes and eukaryotes. • What is the function of the plasma membrane?

3. The Plasma Membrane • What is its purpose? • Helps maintain homeostasis by its structure and selective permeability. • It allows some substances through and keeps other substances out.

4. Form Fits Function • The structure of the plasma membrane controls how, when, and how much of these substances leave the cell.

5. Structure • Phospholipid bilayer makes up the membrane • Arranged tail-to-tail • Phospholipids have a phosphate head (polar) and two fatty acid tails (non-polar) • The arrangements of the phospholipids creates a barrier that is polar at its surface and non-polar in the middle.

7. The polar and non-polar properties of the phospholipid bilayer allows the membrane to separate the inside of the cell from the outside of the cell.

8. Cholesterol, Proteins, and Carbs • Proteins: give structure to the cell • On the outer surface they act as receptors • Help transport needed substances or waste material through the plasma membrane (transport protein)

10. Cholesterol, Proteins, and Carbs • Cholesterol • Prevents the fatty acid tails of the phospholipids from sticking together.

11. Carbohydrates help define the cell’s characteristic and identify chemical signals

12. Fluid Mosaic Model • The plasma membrane is in constant motion • The phospholipids move sideways • Other components move among the phospholipids