Understanding Plasma Membrane: Structure, Function, and Importance

1. Chapter 5 Membrane Structure and Function part I Page ref. 84-86

2. Memorize these words!!! • inter – within ie. Hilo to Honolulu • intra – between, among ie. Hilo to Kona • extra – outside of (extracellular would be outside the cell) • glyco – containing sugar/carbohydrates (sugar-coated)

3. The fluid-mosaic model of the plasma membrane • The cell membrane is a fluid, phospholipid bilayer in which protein molecules are either fully or partially embedded. (see fig. 5.1 and 5.2)

4. Plasma membrane functions • to separate the internal from external environment of the cell • Regulates materials entering and leaving the cell. • Helps the cell, in turn the organism, maintain homeostasis

5. Plasma membrane structure • Made up of a phospholipid bilayer • Phospholipid: a molecule with a hydrophilic (water-loving) head and a hydrophobic (water-fearing) tail

6. Plasma Membrane Components • Cholesterol: a lipid found in bilayer, for strength of membrane • Proteins: peripheral (inside surface of membrane) or integral (embedded in membrane) • Some integral proteins protrude from one surface of bilayer, some protrude from both (transmembrane) • Phospholipids and proteins can have attached carbohydrate (sugar) chains. These are called glycolipids, and glycoproteins, respectively

7. Carbohydrate Chains • Carbohydrate chains of proteins in animal cell give cell a “sugar coat” called the glycocalyx. • Functions of the glycocalyx include protection of the cell, enables cells to adhere to one another, reception of signal molecules, and for cell-to-cell recognition

8. Fluidity of Plasma Membrane • Membrane fluidity critical to it’s functioning • At body temperature, it has the consistency of olive oil • This allows the cell to do all it needs to do – it makes the cell pliable

9. Homework • Due Thursday • All vocab AND • Reviewing chapter - #1-3 • Testing yourself 2,3,11,12,13,14