Spring 2011 Biol/Chem 410
Biochemistry Exam II
Name __________________________
Part I Pick 4 of the following (short essays but supported with fact – 10 points each):
1 PET scans are often used to identify cancerous masses in a living person. What is a PET scan and explain the
basics of the scan. Explain why this technique is helpful in detecting cancerous cells from non-tumor tissue.
2 What is PEPCK? What is it’s role in the cell and how is it regulated?
3 Individuals with McArdle’s disease often experience a “second wind” resulting from cardiovascular
adjustment that allows glucose mobilized from liver glycogen to fuel muscle contraction. Explain why the
amount of ATP derived in the muscle from circulating glucose is less than the amount of ATP that would be
obtained by mobilizing the same amount of glucose from muscle glycogen.
4 Explain which of the following nucleotides (AMP, ADP and or ATP) act as a signal of low energy state in
the cell. AND explain why? What enzyme reaction is involved with the production of AMP?
5 Pyruvate kinase in muscle and liver are essentially the same with only a minor difference in their amino
acid sequence. Yet one enzyme can be active when the other is inactive. How is this so?
6 The concentration of lactate in blood plasma before, during and after a 400 m sprint are shown in the
graph
200
RUN
Blood
Lactate(µM)
After
100
Before
0
a) what causes the rapid rise in lactate concentration?
b) What causes the decline in lactate concentration after completion of the sprint? Why does the
decline occur more slowly than the increase?
c) Why is the concentration of lactate not zero during the resting state?
Part II Do EACH of the following (short essays but supported with fact – 10 points each):
1 Addition of an ionophore to a cultured dish of hepatocytes, permits high concentrations of calcium to
enter the cell. You observe that this leads to a decrease in cellular glycogen. Propose a mechanism for
this phenomenon and determine a means to test for your hypothesis.
2 What are the forms of diabetes? What are the main causes (describe in terms of the biochemistry protein and or gene please?).
Part III Do 2 of the following as a fully supported detailed essay (20 points each)
1 Predict the major consequence of each of the following mutation on the action of the enzyme AND the
effect on blood sugar concentration WITH a brief explanation of why this happens.
2
3
-
Loss of the AMP-binding site in muscle phosphorylase
Mutation of Ser14 to Ala14 in liver phosphorylase
Over expression of phophorylase kinase in the liver
Loss of the gene that codes for glycogenin in liver
Loss of GTPase activity of the G protein alpha subunit
-
Loss of the cAMP-binding site on the regulatory subunit of protein kinase A
Describe the structural AND regulatory mechanism by which PFK and FBPase are reciprocally
regulated.
Examine how the G subunit of PP1 regulates glycogen metabolism
8 Pyruvate kinase in muscle and liver are essentially the same with only a minor difference in their amino
acid sequence. Yet one enzyme can be active when the other is inactive. How is this so?
9 Addition of an ionophore to a cultured dish of hepatocytes, permits high concentrations of calcium to
enter the cell. You observe that this leads to a decrease in cellular glycogen. Propose a mechanism for
this phenomenon and determine a means to test for your hypothesis.
10 Predict the major consequence of each of the following mutation on the action of the enzyme AND
the effect on blood sugar concentration WITH a brief explanation of why this happens.
-
Loss of the AMP-binding site in muscle phosphorylase
-
Mutation of Ser14 to Ala14 in liver phosphorylase
Over expression of phophorylase kinase in the liver
Loss of the gene that codes for glycogenin in liver
Loss of GTPase activity of the G protein alpha subunit
-
Loss of the cAMP-binding site on the regulatory subunit of protein kinase A
11 The concentration of lactate in blood plasma before, during and after a 400 m sprint are shown in the
graph
200
RUN
Blood
Lactate(µM)
After
100
Before
0
d) what causes the rapid rise in lactate concentration?
e) What causes the decline in lactate concentration after completion of the sprint? Why does the
decline occur more slowly than the increase?
f) Why is the concentration of lactate not zero during the resting state?
12
13
Describe the structural AND regulatory mechanism by which PFK and FBPase are reciprocally
regulated.
Examine how the G subunit of PP1 regulates glycogen metabolism