Chapter 13 (Additional pathways in carbohydrate metabolism)
1) Glyoxylate Cycle
a. Know that it is a way that some organism can use acetyl-CoA to
synthesize carbohydrates. Know why organisms without this pathway can
not do this
b. Know where malate synthase and isocitrate lyase by-pass the
decarboxylation steps of TCA.
c. Be able to recognize the intermediates of the glyoxlate cycle and know
where they fit into the TCA cycle and where they feed into
gluconeogenesis.
d. Know what reactions occur in what sub-cellular organelle.
e. Know the allosteric modulators of glycogen phosphorylase activity.
2) Glycogen catabolism
a. Know the reactions of glycogen breakdown. Know which end of the
molecule glycogen phosphorylase cleaves. Know how debranching of the
limit dextran occurs.
b. Know how glycogen is synthesized. Know that UDP-Glucose is an
important precursor. Know how the glycogen synthase is primed using
glycogenin.
c. Know the allosteric regulators of glycogen synthase activity.
3) Hormonal regulation of glycogen metabolism.
a. Know how epinephrine, insulin, and glucagons regulate glycogen
metabolism.
b. Know the hormone signal transduction pathways involved in the
regulation of glycogen synthase and glycogen pyrophosphorylase activity.
4) Gluconeogenesis.
a. Know the names of the pathway intermediates and enzymes involved and
be able to recognize the structure of all pathway intermediates of
gluconeogenesis (you should already know this from glycolysis)
b. Know the three regulated steps of gluconeogenesis and the allosteric
modulators involved in each step. Know the analogous enzymes and
modulators involved in glycolysis.
c. Know where compounds other than pyruvate can enter gluconeogenesis.
d. Really understand the reciprocal regulation of gluconeogenesis in relation
to glycolysis.
e. Understand the role of glucose-6-phosphatase in gluconeogenesis.
f. Know which organ systems are capable of gluconeogenesis.
5) Pentose Phosphate Pathway
a. Know the main functions of this pathway
b. Know what occurs in the two main stages of this pathway (don’t need to
memorize the pathway – you will need to for the calvin cycle)