Membrane Structure, Function, and Transport
Week 5.2
Supplemental Instruction
Iowa State University
Leader: Natalie
Course: BIOL 212
Date: 2/11/14
Chapter: 5
1. What do the terms fluidity and semifluid membrane mean?
2. Do lipids flip-flop from one side of the plasma membrane to the other?
3. Molecule A has long fatty acyl tail, is saturated, and contains cholesterol. Does Molecule A make
the membrane more or less fluid? (hint: how do these factors contribute to fluidity?)
4. What did the Larry Frye and Michael Edidin experiment on lateral movement show?
5. What two sites synthesize most lipids?
6. What three ways are there to move across a membrane? List which of these require energy.
7. Which of the three options above would be required to move K+ from a low K+ concentration
outside the cell into a cell with high K+ concentration?
8. List these from high to low permeability. Carbon dioxide, Mg2+, Leucine, urea, RNA
9. What does it mean to have an ion electrochemical gradient? Give an example of one.
10. What does it mean to have a transmembrane gradient? Give an example of one.
11. If Molecule B has a solute concentration that is higher inside of the membrane than outside,
what would you call this molecule?
12. Refer to question 11. What direction would water flow due to osmosis?
13. What kind of pump is the Na+/K+ pump?