ADS 520
Exam 1
April 22, 1996                     Name________________________


 1. (7 pts)  The major part of starch digestion is catalyzed by

    the enzyme ________________________ (specific name) which is

    secreted by the ___________________ (organ).   The major end

    products of this enzyme are the disaccharide _______________

    and a highly branched compound called ____________________.

    The disaccharide is eventually hydrolyzed to form __________

    by an enzyme called _______________________ which is located

    _________________________ (specific location).

 2. (6 pts)  Describe and illustrate the hydrolytic action of
    lipase on triglycerides.














 3. (13 pts)   During starvation, the carbon for most of the
    blood glucose comes from amino acids.  Two other sources of

    carbon, although relatively minor, are ___________________

    and _____________________.  

    Two hormones effect the mobilization of amino acids; one
    responds more rapidly and the other is involved in longer-term 
    regulation.  Name these, the organ that produces each,
    and the location or cell type in the organ:

                      Hormone     Organ     Location/cell type  

 A. (rapid response)_______________________________________________

 B. (long term)     _______________________________________________

    Another hormone, _________________________ stimulates rapid
    fat mobilization which spares the need for glucose.  This
    hormone is produced by (organ & location)
    _____________________________________________.
    Before an amino acid can enter gluconeogenic pathways, for
    example at pyruvate, the amino group is removed by one of

    two processes called __________________________________ or

    _________________________.  Both of these reactions require

    the vitamin _____________________ as a coenzyme.

 4. (8 pts)   During gluconeogenesis, amino acids are
    metabolized to form new glucose.  There are at least four
    amino acids that ultimately are transaminated to form
    alanine which then is deaminated to form pyruvate.  Pyruvate
    then has to be converted to phosphoenol pyruvate (PEP), but
    this step is not directly reversible.  Illustrate, with
    brief discussion, how an amino acid can become pyruvate, and
    how pyruvate then is converted to PEP.  Show cellular
    location (cytosol vs mitochondria), keep track of the number
    of carbons (whether the compounds have 3 or 4 carbons), and
    mention the role of at least three B-vitamins.  (The
    structures of a "general" amino acid and alanine were given.)
    
    


    













 5. (6 pts)  Sometimes, tissue such as muscle will oxidize an
    amino acid for energy.  Explain what happens to the amino
    group in this situation, and why this series of events is
    important.












 6. (3 pts)  When the body needs to mobilize fat to be oxidized
    for energy, free fatty acids will be released into the blood
    and transported to other cells.  What keeps these fatty
    acids soluble in the aqueous blood?





 7. (6 pts)  Compare fatty acid synthesis in ruminants vs.
    nonruminants.  This does not have to be long, but it does
    require discussion of specific details.
















 8. (4 pts)  Gluconeogenesis is of primary importance to both
    ruminants and nonruminants.  Under normal situations, when
    is gluconeogenesis most important for each (fed state or
    fasting state), and what are the main substrates?

                           Ruminants         Nonruminants

    Physiological state__________________   __________________

    Major substrate(s) __________________   __________________

 9. (9 pts)  Name the essential fatty acids (EFA) and explain
    why each is important.  There is one fatty acid sometimes
    listed as an EFA, but technically is not.  Name it, and
    explain why it is not an EFA.










10. (6 pts)  "A-V differences" (calculated as venous blood
    concentration minus arterial blood concentration) are
    sometimes used as a method to measure absorption of
    nutrients from the intestine.  In ruminants, it is not
    unusual for glucose A-V differences to be negative.  Explain
    why.











    b. What other measurement must be taken for A-V differences
       to be meaningful as a measure of absorption?





11. (12 pts)  Using the energy abbreviations that were used in
    class, which component of the energy scheme would be
    determined by the equations given below?

    a. HNM + HF = ________________

    b. BMR + VA = ________________

    c. ME - HI - (BMR + VA) = ________________

    d. HNM + HF + NEm = ________________

    e. ME - NEp = ________________

    f. NEm + NEp + HI + FE + GPD + UE + = ________________

12. (3 pts)  Define heat increment, using no more than 20 words. 
    The formula for calculating HI is not a definition.





13. (4 pts)  What is the difference between endogenous and
    metabolic energy losses?