Question

Tyrosine has a polar side chain because:
a.) It is asymmetrical
b.) It has two types of atoms that have large differences inelectronegativity
c.) It is symmetrical
d.) both a and b
e.) both b and c

2. Consider the amino acid T at pH 9.23. Its alpha carboxyl grouphas a pKa of 2.63. What is the ratio of
base to acid for this group at this pH?
a.) 1:1
b.) 45637:1
c.) 2,634,678:1
d.) 3,981,072:1
e.) 9,364,345:1

3. Which statement about pKa is not true?
a.) It represents a pH at which 50% of the titratable group is inthe acid form and 50% is in the
base form.
b.) If the pH is less than the pKa, more than 50% of the titratablegroups are unprotonated.
c.) If the pH is greater than the pKa, more than 50% of thetitratable groups are in the base
form.
d.) If the pH is less than the pKa, more than 50% of the titratablegroups are in the acid form.
e.) All of the above are true.

4. At what approximate pH will D most likely exist as azwitterion?
a.) 3.0
b.) 4.0
c.) 5.0
d.) 6.0
e.) 7.0

5. Cysteine is the only amino acid that can form covalent bondswith other amino acids (i.e. cysteine)
through its side chain.
a.) true
b.) false

6. At pH 2, will the R group of H likely be charged OR uncharged?