Bioenergetics/ Carb metabolism

Question 1

characterized by neonatal jaundice, vomiting, cataract formation, hepatomegaly, and failure to thrive.

What enzyme is deficient?

Answer 1

Galactose-1-phosphate uridyl transferase

Classic Galactosemia

Question 2

Ingestion of sucrose/sorbitol is converted into what in the body?

Answer 2

Fructose

Question 3

Fructose can become F6P via what enzyme?

Answer 3

Hexokinase

Question 4

Fructose can become F1P via what enzyme?

Answer 4

Fructokinase

Question 5

Fructose 1 Phosphate can be split into Glyceraldehyde & DHAP via what enzyme?

Answer 5

Aldolase B

Question 6

Patient with very low exercise tolerance (like lifting weights), dramatically improves after having a sugary drink. What enzyme is deficient?

Answer 6

myophosphorylase (a glycogen phosphorylase)

Deficiency = decreased breakdown of glycogen during exercise, resulting in poor exercise tolerance, muscle cramps, and rhabdomyolysis.

Question 7

Decreased breakdown of glycogen during exercise, resulting in poor exercise tolerance, muscle cramps, and rhabdomyolysis (Myoglobinuria).

What illness causes this?

Answer 7

McArdles (v)

myophosphorylase deficiency

Question 8

During gluconeogenesis, phosphoenolpyruvate carboxykinase uses ___ to synthesize phosphoenolpyruvate from oxaloacetate.

Answer 8

GTP

*made by Succinyl-CoA synthase

Question 9

Galactokinase deficiency causes neonatal cataract formation due to accumulation of ___ in the lens

Answer 9

galactitol

Question 10

____ deficiency causes chronic hemolytic anemia, splenomegaly, and iron overload as a result of impaired erythrocyte survival.

Answer 10

Pyruvate kinase

Question 11

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

Answer 11

glycogen phosphorylase

Question 12

The metabolism of ethanol by alcohol dehydrogenase and aldehyde dehydrogenase reduces NAD+ to NADH and ____ the NADH/NAD+ ratio.

Answer 12

increases

*This inhibits processes that need NAD+ like GLUCONEOGENESIS!

Question 13

___ inhibits gluconeogenesis and can cause hypoglycemia once hepatic glycogen stores are depleted.

Answer 13

Ethanol

Question 14

___ 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.

Answer 14

Galactokinase

Question 15

____ deficiency often presents in infancy with lactic acidosis and neurologic defects (seizures, opthalmoplegia, hypotonia etc.)

Answer 15

pyruvate dehydrogenase

Question 16

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.

Answer 16

pyruvate dehydrogenase

Question 17

Lysine and leucine are exclusively ____ amino acids; they cannot be metabolized to pyruvate

Answer 17

ketogenic

• good for people with pyruvate dehydrogenase deficiency

Question 18

The rate-limiting enzyme in the pentose phosphate pathway, the major source of cellular NADPH.

Answer 18

Glucose-6-phosphate dehydrogenase

Question 19

Enzyme is necessary for reducing glutathione (protects red blood cells from oxidative damage) and for the reductive biosynthesis of cholesterol, fatty acids, and steroids.

Answer 19

Glucose-6-phosphate dehydrogenase

Question 20

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.

Answer 20

oxidative stress

Question 21

______ converts glucose to sorbitol.

This pathway increases significantly in diabetes mellitus and contributes to chronic complications such as neuropathy and retinopathy.

Answer 21

Aldose reductase

Question 22

_____ is impaired in Fructosemia causing severe hypoglycemia.

Consequences of hypoglycemia include lethargy, sweating, vomiting, and dehydration

Answer 22

gluconeogenesis

Question 23

____ deficiency causes galactose buildup and this excess is converted to galactitol, an osmotic agent that causes cataracts.

Answer 23

Galactokinase

This deficiency presents later in life than a Galactose-1-Phosphate UT deficiency that presents in infancy.

Question 24

Hypoglycemia, hepatomegaly, hypotonia
Muscle weakness, ketoacidosis 
Hepatic fibrosis (+/-)

Cytosolic accumulation of glycogen with abnormally short outer chains (limit dextrins).

Answer 24

Cori (III)

Question 25

Affects mainly the liver and kidney
hypoglycemia, lactic acidosis, hyperlipidemia, hyperuricemia.

Hepatic steatosis is a cardinal manifestation of the disorder.

Answer 25

Glucose-6-phosphatase deficiency

von Gierke disease

Question 26

serves as a cofactor for:
isocitrate dehydrogenase
alpha-ketoglutarate dehydrogenase
malate dehydrogenase

Answer 26

Vit B3 Niacin

Question 27

Succinate dehydrogenase is an enzyme of the citric acid cycle; it catalyzes the conversion of succinate to fumarate using ___ as a cofactor.

Answer 27

Vit B2

flavin adenine dinucleotide (FAD)

Question 28

Vitamin Deficiency
Clinical manifestations include angular stomatitis, cheilitis, glossitis, seborrheic dermatitis, eye changes (eg, keratitis, corneal neovascularization), and anemia.

Answer 28

Vit. B2