1. Using just A, K, and D, create 2 strings of at least 25 amino acids each that would result in two -helices that stick together at pH 7.

2. A selective potassium channel likely has an abundance of which amino acids in order to select for potassium? What would you suspect is the optimal pH for this protein to function?

3. A protein is purified from a halophile (an organism that lives in extremely high salt environment). Explain why this protein might lose its function when placed in deionized water. (Hint: form = function, so what is affecting its structure?)

4. Carbonic acid (H2CO3) has pKa values of 6.37 and 10.32. It is a buffer species found in the blood, whose pH is typically 7.4. How much carbonic acid is in the ionized form and how much is in the acid form in blood? Is this a good buffer for this pH?