Chem 103
Learning Objectives
Chapter 19
1. Be able to draw the general structure of an amino acid – the acidic form, the
zwitterionic form, and the basic form. What does an amino acid look like at
low/high pH?
2. Given an amino acid, be able to categorize it as nonpolar, polar, acidic, or
basic.
3. Be able to distinguish between D and L amino acids. Which form is found in
nature?
4. What is an isoelectric point? What is the charge on an amino acid at the pI?
What is the charge on an amino acid at a pH lower than the pI? Higher than the
pI? Be able to draw an amino acid in the proper form at a particular pH, if given
its pI.
5. How can electrophoresis be used to separate mixtures of amino acids?
6. Define C terminal, N terminal, peptide, peptide bond.
7. Define primary, secondary, tertiary, and quaternary structure. Define alpha
helix/beta pleated sheet – what interactions are used to hold these structures?
8. Be able to name at least two types of interactions between R groups that
stabilize tertiary structure (and, for that matter, quaternary structure).
9. We said that interactions found in tertiary and quaternary structure are the
same. What, then, is the difference between tertiary and quaternary structure in
proteins?
10. What does it mean to denature a protein – what parts of a protein’s structure
are disrupted? Name and describe a few methods of protein denaturation.
11. How is protein hydrolysis different from protein denaturation? (what results
from hydrolysis, and what results from denaturation?)
NEW OBJECTIVES ADDED
1a. Determine the sequence of a peptide given fragments after acid or enzyme
hydrolysis. Also, understand the role of carboxypeptidase and Edman
degradation in learning the N and C terminal amino acids.
2a. How does pKa tie into acidity? (lower pKa = more acidic, etc) Be able to
assign pKa values to acidic sites in a di- or triprotic amino acid as done in class,
and explain why one group may be more acidic than another (i.e. the two
carboxyl groups with one being closer to the electron-withdrawing amino
function).
3a. If given a chart of the 20 amino acids, be able to name two amino acids that
would interact via a particular R group interaction type. Or, given a particular
amino acid, name another amino acid that would interact with it, and
explain/draw how.