Week of Introductions

Welcome to General Biology II at Vanier College.

The primary function of this website is to provide you with study questions and provide you with a open means to communicate solutions to given problems. This way, you can see where your classmates are at, and you can solve these questions as a group.

First Study Topic: Cell Membranes

1. If a eukaryotic cell has a diameter that is 10 times that of a bacterial cell, proportionally how much more surface area would the eukaryotic cell have? Proportionally how much more volume would it have?
2. In your own words, describe the molecular structure of the plasma membrane.
3. A solution of 1 molar (M) glucose is separated by a selectively permeable membrane from a solution of 0.2 M fructose and 0.7 M sucrose. The membrane is not permeable to the sugar molecules. Indicate which side initially has more free water molecules, and which side has fewer. What is the result in volumes (higher or lower) for sides A and B after osmosis has occurred?

4. The ratios of saturated to unsaturated phospholipids in an organism’s membranes can change in response to changes in environmental conditions. In warm environments, how would you expect the fatty acid tails of the membrane phospholipids of tropical plants to be different than those of fish living in cold waters? (HINT: consider how permeability and fluidity of a membrane that contains a low percentage of unsaturated phospholipids compare with those of a membrane that contains a high percentage of unsaturated phospholipids.)

5. Use your knowledge of how the concentration of solutions outside cells affects cell shape to explain why salting meat is an effective way to preserve it (and keep bacteria from rotting it).

6. Tough Question: How is cholesterol transported into human cells? Explain why cholesterol accumulates in the blood of individuals with the disease familial hypercholesterolemia?