Introduction to Biochemistry
Mid-term Examination - Group
Wednesday, 27 March 2002
H. B. White - Instructor
Important - Please read this before you turn the page.
Write your names or group number on each page.
You may refer to your notes, course reader, handouts, or
graded homework assignments. Reference books in the course library may
be consulted briefly and returned.
Please read the question carefully and make sure that you
have thought it through with everyone’s input before converging on a solution.
1. (9 Points) Zinoffsky carefully determined the empirical
formula for horse hemoglobin in 1886. From that formula, one can calculate
a minimum molecular weight of 16,700, a number mentioned both by Conant
and by Svedberg and Fåhraeus in the mid 1920's. Knowing what is now
known about hemoglobin structure, would it have been possible for anyone
to get an empirical formula that matched the molecular formula for hemoglobin
using the methods of Zinoffsky? Explain your reasoning.
2. (8 Points) Draw a diagram depicting the forces acting
on a hemoglobin molecule spinning in Svedberg's centrifuge. Describe your
diagram in words and formulas as needed.
3. (8 Points) In his electrochemical titrations, Conant
observed that that the oxidation-reduction potential he calculated for
hemoglobin varied as a function of pH within certain ranges and depended
on whether oxygen, carbon monoxide, or no ligand was attached to the iron.
Conceptually, why does pH or ligand binding have any effect on the reduction
potential of hemoglobin?
(5 Point Bonus) The arterial blood of a typical college
student contains about 16g of oxyhemoglobin per 100ml. Estimate how many
ml of oxygen per 100ml of blood does that represent at standard temperature
and pressure? (Note: Estimation does not require a calculator. Any answer
within a factor of 2 is correct. Show work for credit.)
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Last updated: 28 March
2002 by Hal White
Copyright 2002, Department
of Chemistry and Biochemistry, University of Delaware