BIO 143 Chapter Notes - Chapter 5: Lipid Bilayer, Semipermeable Membrane, Passive Transport
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BIO143: Chapter 5 Study Guide
Chapter 5: Cell membrane structure and function
I. How is the structure of the membrane related to its function?
A. Cell membranes isolate the cell contents while allowing communication with
1. What are the five major functions of the cell membrane?
2. Membrane function is dependent on membrane structure
B. Membranes are “fluid mosaics” in which proteins move within the double layer
1. Why is the membrane referred to as the “fluid mosaic” model?
C. The phospholipid bilayer is the fluid portion of the membrane
1. What are the two major structural components of the
phospholipids? What are the characteristics in relation to water/fluid?
2. How are the phospholipids arranged in the membrane? Why are
they arranged in this fashion?
3. Are phospholipids bonded to each other?
4. Some phospholipids have “kinks” in their “tails,” why is this
important? What environmental factor can change the structure of
the phospholipid tails?
5. What is the main function of phospholipids?
6. Cholesterol is also present in animal cell membranes to make the
bilayer more stable, less fluid, and less permeable to water-soluble
D. A variety of proteins form a mosaic within the membrane
1. Proteins are usually modified, in which a carbohydrate molecule
attaches to the protein. These are called ____________?
2. What are the five major categories of proteins found in the
a. There are two types of transport proteins. One forms a pore for
small water-soluble molecules; the other binds molecules and
moves them across membranes without the use of energy.
II. How do substances move across membranes?
A. Molecules in fluids move in response to gradients
1. Fluids have many characteristics
a. What are solutes?
b. What is concentration?
c. What is gradient?
2. Define diffusion
a. During diffusion, molecules move continuously and randomly