Organic Chemistry III
	Professor Carl C. Wamser
Chem 336 - Spring Term	Pre-Quiz 27

(must be done in Blackboard before Mon., May 17, 8:30 am)

1. Histidine has pKa values of 1.82, 6.00, and 9.17.
At pH 7, histidine would be expected to have what charge?

a. -2
b. -1
*c. 0
*d. +1
e. +2

2. An amino acid with TWO chirality centers is

a. glycine
b. valine
c. leucine
*d. threonine
e. tyrosine

3. In the tripeptide SerGluPhe, there will be a carboxylic acid group (-COOH, assuming the conditions are suitably acidic) on which amino acid(s)?

a. only Ser
b. only Glu
c. only Phe
d. none
*e. Glu and Phe

4. A Strecker synthesis that started with 2-methylbutanal would give which amino acid?

a. valine
b. leucine
*c. isoleucine
d. serine
e. threonine

5. Two amino acids that have side chains that could form a salt bridge with one another are

a. Lys and Arg
b. Gln and Tyr
c. Asp and Ser
*d. Glu and Lys
e. His and Phe