Bioenergetics/ Carb metabolism Flashcards
characterized by neonatal jaundice, vomiting, cataract formation, hepatomegaly, and failure to thrive.
What enzyme is deficient?
Galactose-1-phosphate uridyl transferase
Classic Galactosemia
Ingestion of sucrose/sorbitol is converted into what in the body?
Fructose
Fructose can become F6P via what enzyme?
Hexokinase
Fructose can become F1P via what enzyme?
Fructokinase
Fructose 1 Phosphate can be split into Glyceraldehyde & DHAP via what enzyme?
Aldolase B
Patient with very low exercise tolerance (like lifting weights), dramatically improves after having a sugary drink. What enzyme is deficient?
myophosphorylase (a glycogen phosphorylase)
Deficiency = decreased breakdown of glycogen during exercise, resulting in poor exercise tolerance, muscle cramps, and rhabdomyolysis.
Decreased breakdown of glycogen during exercise, resulting in poor exercise tolerance, muscle cramps, and rhabdomyolysis (Myoglobinuria).
What illness causes this?
McArdles (v)
myophosphorylase deficiency
During gluconeogenesis, phosphoenolpyruvate carboxykinase uses ___ to synthesize phosphoenolpyruvate from oxaloacetate.
GTP
*made by Succinyl-CoA synthase
Galactokinase deficiency causes neonatal cataract formation due to accumulation of ___ in the lens
galactitol
____ deficiency causes chronic hemolytic anemia, splenomegaly, and iron overload as a result of impaired erythrocyte survival.
Pyruvate kinase
Glycogen is broken down by the enzyme ____, which is regulated through phosphorylation (active state) and dephosphorylation (inactive state).
Phosphorylase kinase (PK) = phosphorylation Phosphoprotein phosphatase = dephosphorylation
glycogen phosphorylase
The metabolism of ethanol by alcohol dehydrogenase and aldehyde dehydrogenase reduces NAD+ to NADH and ____ the NADH/NAD+ ratio.
increases
*This inhibits processes that need NAD+ like GLUCONEOGENESIS!
___ inhibits gluconeogenesis and can cause hypoglycemia once hepatic glycogen stores are depleted.
Ethanol
___ phosphorylates galactose and its deficiency typically causes less severe manifestations of Galactosemia with cataract formation being the most common manifestation, but liver and renal functions are preserved.
Galactokinase
____ deficiency often presents in infancy with lactic acidosis and neurologic defects (seizures, opthalmoplegia, hypotonia etc.)
pyruvate dehydrogenase
Generates acetyl-CoA from pyruvate (links glycolysis and TCA)
A deficiency causes a buildup of pyruvate, which is shunted to become lactate (lactate dehydrogenase) causing severe lactic acidosis.
pyruvate dehydrogenase
Lysine and leucine are exclusively ____ amino acids; they cannot be metabolized to pyruvate
ketogenic
- good for people with pyruvate dehydrogenase deficiency
The rate-limiting enzyme in the pentose phosphate pathway, the major source of cellular NADPH.
Glucose-6-phosphate dehydrogenase
Enzyme is necessary for reducing glutathione (protects red blood cells from oxidative damage) and for the reductive biosynthesis of cholesterol, fatty acids, and steroids.
Glucose-6-phosphate dehydrogenase
In G6PD deficiency, RBCs can’t make enough reduced glutathione during periods of increased ______, which occurs with certain infections, consumption of fava beans, or specific medications (primaquine, sulfa drugs).
Resulting in acute hemolytic anemia and jaundice.
oxidative stress
______ converts glucose to sorbitol.
This pathway increases significantly in diabetes mellitus and contributes to chronic complications such as neuropathy and retinopathy.
Aldose reductase
_____ is impaired in Fructosemia causing severe hypoglycemia.
Consequences of hypoglycemia include lethargy, sweating, vomiting, and dehydration
gluconeogenesis
____ deficiency causes galactose buildup and this excess is converted to galactitol, an osmotic agent that causes cataracts.
Galactokinase
This deficiency presents later in life than a Galactose-1-Phosphate UT deficiency that presents in infancy.
Hypoglycemia, hepatomegaly, hypotonia Muscle weakness, ketoacidosis Hepatic fibrosis (+/-)
Cytosolic accumulation of glycogen with abnormally short outer chains (limit dextrins).
Cori (III)
Affects mainly the liver and kidney
hypoglycemia, lactic acidosis, hyperlipidemia, hyperuricemia.
Hepatic steatosis is a cardinal manifestation of the disorder.
Glucose-6-phosphatase deficiency
von Gierke disease
serves as a cofactor for:
isocitrate dehydrogenase
alpha-ketoglutarate dehydrogenase
malate dehydrogenase
Vit B3 Niacin
Succinate dehydrogenase is an enzyme of the citric acid cycle; it catalyzes the conversion of succinate to fumarate using ___ as a cofactor.
Vit B2
flavin adenine dinucleotide (FAD)
Vitamin Deficiency
Clinical manifestations include angular stomatitis, cheilitis, glossitis, seborrheic dermatitis, eye changes (eg, keratitis, corneal neovascularization), and anemia.
Vit. B2
