Tutorial Sheet for practice for Premed.
1. Consider the oligopeptide chain below and the table of pKa values and answer the
questions that follow:
Glu-Asp-Lys-Cys-Asp
Glu Asp Lys Cys
pKa1 2.1 2.0 2.2 1.9
pKa2 9.5 9.9 9.2 10.8
pKa3 4.1 3.9 10.8 -
a) Define pKa value of amino acid groups and state its importance. 5 marks
b) Draw the molecular structure of the oligopeptide shown above at pH 4.0. 10
marks
c) Determine the net charge on the molecule and predict which direction (cathode or
anode) of electrophoresis it would migrate to at pH 4. 5 marks
2. With the aid of diagrams, show what the titration curve for the following amino acids
looks like.
a) Aspartate
b) Lysine
c) Cysteine
3. Briefly describe the four levels of protein structure.
4. Discuss the classification of proteins based on the following criteria. Give examples:
a) Shape of molecule
b) Chemical composition
c) Functions
5. Describe the differences in structure between the following types of hemoglobin:
a) Normal adult hemoglobin and fetal hemoglobin
b) Normal adult hemoglobin and sickle cell hemoglobin
6. Draw a table to compare hemoglobin and myoglobin based on the following criteria:
a. Structure
b. Function
c. Location
d. Oxygen affinity
7. Describe the molecular structure of collagen and state the biochemical role of vitamin
C in collagen synthesis.
8. List any three plasma proteins and state their functions.
1. Consider the oligopeptide chain below and the table of pKa values and answer the
questions that follow:
Glu-Asp-Lys-Cys-Asp
Glu Asp Lys Cys
pKa1 2.1 2.0 2.2 1.9
pKa2 9.5 9.9 9.2 10.8
pKa3 4.1 3.9 10.8 -
a) Define pKa value of amino acid groups and state its importance. 5 marks
b) Draw the molecular structure of the oligopeptide shown above at pH 4.0. 10
marks
c) Determine the net charge on the molecule and predict which direction (cathode or
anode) of electrophoresis it would migrate to at pH 4. 5 marks
2. With the aid of diagrams, show what the titration curve for the following amino acids
looks like.
a) Aspartate
b) Lysine
c) Cysteine
3. Briefly describe the four levels of protein structure.
4. Discuss the classification of proteins based on the following criteria. Give examples:
a) Shape of molecule
b) Chemical composition
c) Functions
5. Describe the differences in structure between the following types of hemoglobin:
a) Normal adult hemoglobin and fetal hemoglobin
b) Normal adult hemoglobin and sickle cell hemoglobin
6. Draw a table to compare hemoglobin and myoglobin based on the following criteria:
a. Structure
b. Function
c. Location
d. Oxygen affinity
7. Describe the molecular structure of collagen and state the biochemical role of vitamin
C in collagen synthesis.
8. List any three plasma proteins and state their functions.
