L100 - Exam One (part two) - membranes

1.  What is/are the function(s) of membranes? 

2.   Understand the structure of the plasma membrane –

a. phosopholipids – what is special about these molecules that allows for the formation of the membrane?
b. what is the function of embedded proteins

3. What is meant by “selectively permeable?”

4 . Understand the process of passive diffusion of molecules across the membrane.  What molecules tend to pass unaided, and what molecules need transport proteins? What is the difference between passive diffusion and facilitate diffusion?

5.  How does active transport differ from passive diffusion (passive transport)? 

6. What is osmosis?

7.  Be comfortable with what happens when a cell is put into a hypotonic vs. a hypertonic solution.  What is an isotonic solution? Be sure you are comfortable with the different impact on plant and animal cells to these different situations.

8. Explain exocytosis and endocytosis. How do these differ from passive or active transport?

9. You should be able to compare and contrast passive diffusion, facilitate transport, active transport and endocytosis & exocytosis. Which ones require energy? Which ones require a plasma protein? During which does the movement of molecules go up a concentration gradient? or down the concentration gradient?