Discussion Problem Set 1. C483 Spring 2014
Problems from lectures1- 3. 1/13/14, 1/15/14 and 1/17/14
1. Draw the structure of a D- sugar. What is this designation based on? Draw an Lamino acid. What is this designation based on? What process equilibrates D and L
amino acids?
2. What four common acid functionalities are found in biological molecules? Draw
their generic structure and provide an example of each.
3. What general roles do acid functionalities play in the biological function of
metabolites in glycolysis and the Krebs cycle? Which two acid functionalities are
involved?
4. What functionalities play a role in cell surface recognition? What is the dominant
feature of these functionalities?
5. What functionalities play a role in the function of cartilage in joints? How does
this work?
6. What functionality is essential for joining monomer units of DNA? Why is this
used, rather than a carbon ester?
7. ATP is thermodynamically unstable relative to hydrolysis, but is kinetically
stable. Provide an explanation.
8. What is the major structural difference between RNA and DNA? What is the
consequence of this difference in terms of kinetic stability? Why might this be
useful?
9. What is the basic structure of an amphipathic molecule? What higher order
structure do these molecules form? Draw a diagram of these structures. Provide an
example of where this function might play a biological role.
10. What is the basic structure of a phospholipid? What is the most common
phospholipid? How do phospholipids differ from triglycerides?
11. Inorganic phosphate, and phosphate monoesters are present in the cell at high
concentrations. These molecules play an important role in determining the pH of
the cell. Explain why this is so. Where else in biological systems might inorganic
phosphate play an important role in determining pH? Explain.
12. Several problems that utilize the Henderson-Hasselbach equation and its
corollaries.
a) pKa for phenophthalein is 9.3 at room temp.
Calculate ratio of its anionic form to acid form at pH 8.2 and at pH 10.
b) You need to produce a buffer solution that has a pH of 5.27. You already have a
solution that contains 10.0 mmol (millimoles) of acetic acid. How many millimoles of
sodium acetate will you need to add to this solution? The pKa of acetic acid is 4.75
c) What is the pH when 25.0 mL of 0.200 M of CH3COOH has been titrated with 35.0
mL of 0.100 M NaOH?