Download Question 1 (7 points) - Di-Et-Tri

Question 1 (7 points)
The kinetic properties of the glucose transporter 2 (GLUT2) are different from the
other glucose transporters.
a. How? (3)
b. What are the two organs where GLUT2 is mainly expressed? (2)
Explain how the distinct kinetic properties of GLUT2 fits with the function of the
protein in these organs? (2)
Question 2 (4 points)
Fatty acid synthesis describes the conversion of acetyl-CoA to fatty acyl-CoA.
a. What enzyme catalyzes the rate-limiting and committed step in this pathway?(2)
b. Explain how the activity and expression of this enzyme are regulated.(2)
Question 3 (7 points)
In the first few days of fasting, muscle protein is degraded at a very rapid rate.
a. What is the purpose of muscle protein degradation. (2)
b. Which two amino acids are released in large amounts from muscle during fasting ?
(2)
c. What happens to each of these amino acids ? (2)
d. During a prolonged fast, the rate of muscle protein degradation declines. Why
does the need for muscle protein degradation decrease under these conditions ? (1)
Question 4 (5 points)
MODY2 (Maturity-Onset Diabetes of the Young) is an autosomal dominantly inherited
disease caused by a mutation in the glucokinase gene. Researchers at Vanderbilt
University in the USA have made a mouse model for the disease by creating knockout mice that lack the glucokinase gene.
Do you think the homozygous or heterozygous knock-out mice would represent the
best model for MODY2 ? (2)
Explain in detail why a mutation in the glucokinase gene would cause hyperglycemia.
In your answer focus on the role of glucokinase in the pancreas. (3)
Question 5 (4 points)
Explain how and why the fuel used by skeletal muscle changes with exercise
duration and intensity.
Question 6 (5 points)
a. What enzyme is inhibited by lovastatin and simvastatin? (2)
How does inhibition of this enzyme lead to a reduction in plasma cholesterol and LDL
levels? (2) Mention the transcription factor that is involved. (1)
Question 7 (10 points)
Fill in:
A. _____________________ transports cholesterol back from the peripheral tissues
to the liver.
B. The esterification of free cholesterol to cholesterol esters within HDL is catalyzed
by _________________
C. _________________ transports triglycerides synthesized in the intestine to
adipose tissue
D. The enzyme ______________________ catalyzes the rate-limiting step in bile
acid synthesis
E. Lipolysis in adipose tissue during fasting is catalyzed by _________________
F. The transcription factor that serves as a receptor for oxysterols is called
_________________
G. The activity of lipoprotein lipase is activated by ______________________
H. The apoprotein that is synthesized exclusively in intestine is ______________
I. Two target genes of the transcription factor Sterol-Regulatory Element Binding
Protein –2 (SREBP-2) are _____________________ and
_______________________
J. Uptake of chylomicron remnants in the liver is mediated by binding of
___________________ to the LDL-receptor and LDL-receptor related protein.