carbs Flashcards
(24 cards)
What molecule allosterically activates PFK-1?
Fructose 2,6-bisphosphate.
Which enzyme bypasses pyruvate kinase in gluconeogenesis?
Pyruvate carboxylase and PEP carboxykinase (PEPCK).
How is pyruvate kinase regulated?
Allosterically activated by F-1,6-bisP; inhibited by ATP and alanine.
What cofactor is required by pyruvate carboxylase?
Biotin.
How is PFK-1 inhibited?
By high levels of ATP and citrate.
How does insulin affect glycolysis?
Stimulates glycolysis by upregulating PFK-1 and pyruvate kinase.
How does glucagon affect gluconeogenesis?
Stimulates gluconeogenesis by increasing cAMP, activating PKA, which inactivates PFK-2.
What effect does insulin have on glycogen synthesis?
Activates glycogen synthase via dephosphorylation.
What effect does glucagon have on glycogen breakdown?
Activates glycogen phosphorylase via phosphorylation through PKA cascade.
What enzyme is present in liver but not in muscle for gluconeogenesis?
Glucose 6-phosphatase.
Which glucose phosphorylating enzyme has a lower Km, hexokinase or glucokinase?
Hexokinase.
What inhibits hexokinase but not glucokinase?
Glucose 6-phosphate.
Why does muscle lack glucose 6-phosphatase?
So it retains glucose for its own use.
What are symptoms of Von Gierke’s disease?
Fasting hypoglycemia, hepatomegaly, lactic acidosis.
What is a symptom of McArdle’s disease?
Exercise-induced muscle cramps and myoglobinuria.
What is a common trigger for hemolysis in G6PD deficiency?
Oxidative stress from drugs or fava beans.
What accumulates in Hurler syndrome?
Heparan sulfate and dermatan sulfate.
Which GLUT transporter is insulin-sensitive?
GLUT4.
Where is GLUT4 found?
In muscle and adipose tissue.
Where is GLUT2 found?
Liver, pancreas, and kidney; functions in glucose sensing and transport.
What are proteoglycans made of?
GAGs covalently attached to a core protein.
Where are glycosaminoglycans (GAGs) commonly found?
Extracellular matrix, synovial fluid, and connective tissue.
What is the role of hyaluronic acid?
Acts as a lubricant and shock absorber in joints.
