CHEM-342 Introduction to Biochemistry            Name ________________________
Final Examination - Individual Part
Friday, 25 May 2001
3:30 - 5:15 PM
H. B. White - Instructor

Important - Please read this before you turn the page.
 

Part II (25 points) The group part of the examination, has 2 problems, one of which has multiple parts.   There is a 5 point bonus question in each part.

1.    (4 points) What research seminar did you attend? What did you learn?
 
 

2.    (5 points) What is the causal relationship connecting jaundice to anemia among people with sickle cell anemia?

     
3.    (6 points) Allison (1954) notes that newborn infants, regardless of their sickle cell genotype, appear to be resistant to malaria. He correlates susceptibility with the disappearance of red blood cells containing fetal hemoglobin in the months after birth (Figure on p 293). For a child homozygous for the sickle cell gene, would the appearance symptoms of anemia precede, parallel, or lag behind the susceptibility to malaria in children homozygous for the normal gene for hemoglobin? Explain your answer and draw a graph of your prediction.


4.    (15 points) Advances in science often follow the development of new techniques and methodology that can be broadly applied. This semester you have encountered the spectroscope, redox titrations, electrochemical titrations, equilibrium ultracentrifugation, isotopic tracers, Tiselius electrophoresis, paper electrophoresis, paper chromatography, and Edman degradation among others. Select one of these techniques or methods. Describe it and the principle(s) on which it is based. Include examples and diagrams, mathematical equations, and/or chemical equations as necessary.
 
     
5.    (5 points) Bonus Question. On the back of this page, derive the Henderson-Hasselbalch Equation

6.    The diagram below represents the titration of riboflavin with dithonite as it was done in class on 12 February.
 
    A. (5 points) On the above graph, sketch in another graph which would show the expected changes in dissolved oxygen concentration which starts at "X" on the graph.
     

    B. (5 points) Explain, what is happening with oxygen in each of the regions indicated on the graph.
     


7.    Figure 1 from the Shemin and Rittenberg (1946) article is reproduced twice below. Please sketch in the curves that you would expect if the conditions of the experiments were changed in the indicated ways. Your answers will be evaluated on their qualitative merits and whether the depiction corresponds to the written justification you provide.


 

A.    (6 points) What would the hemin and red cell protein data look like if Shemin had a hemolytic anemia like sickle cell anemia?
 

Explanation.


 
     
    B.    (6 points) What would the hemin and red cell protein data look like if Shemin had ingested any other 15N labeled amino acid than glycine?
     

    Explanation.

     

8.    On the next page, there is a representation of the amino acid sequences of the alpha and beta globin chains of rabbit hemoglobin.
A.    (2 points) Put a circle around every sulfur-containing amino acid residue in the rabbit hemoglobin chains.

B.    (5 points) If Zinoffsky had used rabbit hemoglobin instead of horse hemoglobin for his determination of the iron and sulfur content of hemoglobin, what stoichiometry of Fe to S would he have found?

Explain your answer. 9.    (2 points) Use small arrows to identify the position of peptide bonds in the rabbit hemoglobin amino acid sequence (next page) that would be hydrolyzed by trypsin.
    A.    (2 points) How long in amino acid residues is the largest peptide you would expect in a complete trypsin digest of rabbit hemoglobin?

    B.    (5 points) Because the alpha and beta hemoglobin chains arose as a consequence of gene duplication, they retain similarities to the ancestral amino acid sequence despite several hundred million years of independent evolution. Would this similarity cause any problems in distinguishing tryptic peptides derived from the rabbit alpha chain with those from the rabbit beta chain?

10.    Assume that, like Shemin, you wanted to study hemoglobin synthesis but, because you wanted to use a radioactive amino acid precursor, you decided on an animal model (rabbit) rather than self-experimentation. Furthermore, for reasons of subsequent analysis, you wanted to select an amino acid precursor that would label as many different tryptic peptides as possible.

    A.    (3 points) Ignoring expense and availability, which amino acid would be your choice?

    B.    (4 points) What is the basis of your selection?


Rabbit Hemoglobin alpha chain

MVLSPADKTNIKTAWEKIGSHGGEYGAEAVERMFLGFPTTKTYFPHF

DFTHGSEQIKAHGKKVSEALTKAVGHLDDLPGALSTLSDLHAHKLRV

DPVNFKLLSHCLLVTLANHHPSEFTPAVHASLDKFLANVSTVLTSKYR

Rabbit Hemoglobin beta chain

VHLSSEEKSAVTALWGKVNVEEVGGEALGRLLVVYPWTQRFFESFGDL

SSANAVMNNPKVKAHGKKVLAAFSEGLSHLDNLKGTFAKLSELHCDKL

HVDPENFRLLGNVLVIVLSHHFGKEFTPQVQAAYQKVVAGVANALAHKYH
 

The single-letter abbreviations for the 20 amino acids are:

A = Alanine          I = Isoleucine       R = Arginine

C = Cysteine         K = Lysine           S = Serine

D = Aspartic Acid    L = Leucine          T = Threonine

E = Glutamic Acid    M = Methionine       V = Valine

F = Phenylalanine    N = Asparagine       W = Tryptophan

G = Glycine          P = Proline          Y = Tyrosine

H = Histidine        Q = Glutamine


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Posted: 14 June 2001 by Hal White
Copyright 2001, Harold B. White, Department of Chemistry and Biochemistry, University of Delaware