Malnutrition, glycolysis, pyruvate dehydrogenase. see also physical cards Flashcards
Kwashiorkor
protein malnutrition that results in skin lesions, edema, and liver malfunction (fatty change d/t decreased apolipoprotein synthesis). see small child with swollen belly.
(from a protein deficient meal: malnutrition, edema, anemia, liver (fatty)
Marasmus
total calorie malnutrition that results in tissue and muscle wasting, loss of subcutaneous fat, and variable edema. (m for muscle wasting and myrasmus)
Hexokinase vs. glucokinase: what reaction? When is this reaction used? High glucose vs. low glucose?
phosphorylation of glucose to yield glucose-6-P is the first step of glycolysis and first step of glycogen synthesis in the liver.
it is catalyzed by hexokinase or glucokinase, depending on the tissue. at low glucose, hexokinase sequesters glucose in the tissue. at high glucose, excesses are stored in the liver.
hexokinase vs. glucokinase: location, Km, V max, regulated by insulin?, regulated by glucose-6-P?, gene mutation associated with maturity onset diabetes of the young (MODY)
hexokinase: happens in most tissues, but not in liver or pancreatic beta cells. lower Km and higher glucose affinity, lower V max (less capacity), not induced by insulin, inhibited by glucose-6-P, and not associated with MODY
Glucokinase: found in liver and pancreatic beta cells, higher Km (lower affinity), higher V max ( higher capacity), induced by insulin, not inhibited by glucose-6-P, mutations associated with MODY
Aerobic metabolism: total yields. Anaerobic metabolism yields. What can cause glycolysis to produce zero net ATP?
32 ATP via malate-aspartate shuttle in heart and liver; 30 ATP by glycerol-3-phosphate shuttle in muscle.
arsenic causes glycolysis to produce zero net ATP
What is the pyruvate dehydrogenase complex?
mitochondrial enzym complex that links glycolysis and the TCA cycle. it is active in the fed state.
What is the reaction of the pyruvate dehydrogenase complex?
pyruvate + NAD+ + CoA –> Acetyl CoA + NADH + CO2
connection- this is downregulated after alcohol metabolism, since alcohol metabolism uses up lots of the NAD+
What are the cofactors needed for the pyruvate dehydrogenase complex? What other
- Pyrophosphate (B1/thiamine; TTP)
- FAD (B2/riboflavin)
- NAD (B3/niacin)
- CoA (B5/pantothenate)
- lipoic acid
same cofactors as for the alpha-ketoglutarate complex, which converts alpha-ketogluterate to succinyl-CoA in the TCA cycle
How is the pyruvate dehydrogenase complex actiaved by exercise?
incr. NAD+:NADH ratio, incr. ADP, and incr. Ca 2+
Why is arsenic bad for metabolism? Findings?
it inhibits lipoic acid. this prevents pyruvate dehydrogenase complex? you see vomiting, rice-water stools, and garlic breath.
Pyruvate dehydrogenase complex deficiency: what happens?
buildup of pyruvate. Pyruvate gets shunted to lactate and alanine.
Findings in pyruvate dehydrogenase complex deficiancy. treatment.
neuro defects, lactic acidosis, incr. serum alanine starting in infancy.
treatment: incr. intake of ketogenic nutrients (high fat content or high lysine or leucine, since lysine and leucine are the only purely ketogenic amino acids. Remember that ketogenic amino acids can be degraded directly to Acetyl CoA instead of going through a glucose intermediary.
What metabolic events occur in the mitochondria?
fatty acid oxidation, acetyl-CoA production, TCA cycle, oxidative phosphorylation
What metabolic events occur in the cytoplasm?
glycolysis, fatty acid synthesis, HMP shunt, protein synthesis (RER), steroid synthesis (SER), cholesterol synthesis
What metabolic events occur in both the mitochondria and cytoplasm (depending on where you are in the process)?
heme synthesis, urea cycle, gluconeogenesis
