Download Review Problems #2 (Enzyme Review, Phosphatases

Additional Review Problems for Exam 4
1) Regulation of metabolic pathways is achieved by both specific control of enzyme
activity and through regulation of the amount of enzyme that is present. List two general
methods of control that affect enzyme activity rather than enzyme amounts. Which of
these two methods is employed to control cholesterol biosynthesis? List the control
elements that can affect the amount of an enzyme present in the cell. Which of these is
used to control cholesterol biosynthesis?
2) An additional control element relates to cellular location of metabolic pathways. How
is this relevant for the metabolism of fatty acids?
3) A unique level of metabolic control exists in higher organisms that have specialized
organs. Describe how this specialization between muscle and liver allows muscles to
function more effectively using glycolysis.
4) What is the major site of regulatory control of glycolysis? What molecule regulates
the activity of this enzyme?
5) What molecule is the major regulator of the citric acid cycle? Explain how the cycle
is coupled to energy production.
6) What enzyme controls entry of carbon into the Krebs cycle? From a metabolic
regulatory perspective, why is this enzyme so important?
7) What is the committed step of the pentose phosphate pathway? What regulates this
enzyme?
8) Give two examples of pathways that are reciprocally regulated and give an example of
this regulation for each pathway.
9) List the three major metabolic junction molecules. List the possible fates of these
molecules.
10) What is the usual fuel for the brain under normal conditions? What ensures that the
brain will be adequately supplied with this fuel? Under starvation conditions, what other
fuel can the brain utilize.
11) What are the major fuels for muscle? At rest, what fuel is utilized? Why does this
make sense in both kinetic and thermodynamic terms? In order of speed, list the three
fastest energy sources available to muscle.
12) Muscle utilizes a fuel that is not utilized by the liver (and most other tissues). What
fuel is this? How does muscle tissue rid itself of the resulting byproduct of this
metabolism?
13) By what mechanism is the release of fatty acids from adipose tissue coupled to the
availability of glucose? Why does this make sense in metabolic terms?