Plasma Membrane and Cellular Transport
Structure of the Plasma Membrane
1. Why do you think it is important to have a membrane surrounding each of our trillions of cells? Expect varying answers, but the idea is have the students understand the plasma membrane separates the cells from their environment and each other while also regulating the material within each cell. 2. What are two distinctive physical features of phospholipids? Heads are polar (water soluble, hydrophilic) and tails are nonpolar (water hydrophobic).
Describe the conformation of the phospholipid bilayer of the plasma membrane. What abundant fluid leads to his conformation? Because the phospholipids heads are polar and the tails are nonpolar, their orientation is directly influenced by their polar/nonpolar interaction with water. By forming a bilayer, the nonpolar tails point into the space between the layers and can avoid water while the polar heads point towards the outside of each layer and so they can orient towards water. 4. What molecule in the plasma membrane directly affects the membrane’s fluidity? The phospholipids of the bilayer aren’t static, they move laterally around, like a fluid. Cholesterol can reduce or improve the fluidity of the plasma membrane. 5. What is the function of the glycoproteins and glycolipids of the plasma membrane? Glycoproteins and glycolipids serve as cellular identifiers or signatures. They help the cell recognize friend and foe.
Use the illustration to identify the following components of the plasma membrane: cholesterol, glycoprotein, phospholipids, membrane protein, and glycolipid.
Houston Community College
Cellular Transport: Diffusion and Osmosis
1. Define cellular homeostasis. How does the plasma membrane contribute to cellular homeostasis? Cellular homeostasis is the