FIRST EXAM BIOLOGY 580 SPRING, 1998

Question 1READ THE FOLLOWING STATEMENTS:

The active conformation (shape and 3D) of any particular protein depends upon 1 or more of the following:

1. amino acid sequence

2. binding of a ligand (neurotransmitter, growth hormone, second messenger, etc)

3. binding to other proteins(a sarc homology domain of another protein, Gprotein, cytoskeleton)

4. selective binding of ion or nucleotide

5. membrane potential

6. pH

7. presence of lipids

8. phosphorylation of serine-threonine-tyrosine

A.How can all of the 2-8 statements be true if 1 is true?

B. What kinds of control mechanisms keep proteins from being active or inactive all the time? Give examples for two of the above 2-8 statements

2. A. What is wrong with the concept of a membrane as a homogeneous bilayer of lipid with different proteins floating in it?

B. What can you tell about lipids A and B from the phase diagram of their binary lipid mixture?

3.A. What are some differences between ion channel receptors and second messenger receptors?

B. How can the same ligand (adrenaline or acetylcholine- choose one) cause opposite effects in two different kinds of cells?

4.A How is amoeboid movement like smooth muscle contractions, and how is it different?

B. How are ion pumps important in cells? (Do not duplicate answer to 1B.)

5.A. What causes the difference between a resting potential and action potential?

B. What causes changes in cell behavior following an action potential in nerve or muscle?