MPPC Week 2
Terms in this set (64)
What transporter is specific for fructose?
What is the major control pt in glycolysis?
PFK (converts fructose 6 P into fructose 1,6 BP)
Where in glycolysis is ATP consumed?
-step 1 (cat by hexokinase)
-step 3 (cat by PFK)
What enzyme turns pyruvate into Acetyl CoA?
How does insulin reduce blood sugar?
-increases glucose uptake
-increases production of glycogen, lipids, proteins
What steps of glycolysis are irreversible?
-step 1 (hexokinase)
-step 3 (PFK)
-step 10 (pyruvate kinase)
What enzyme converts pyruvate into oxaloacetate?
pyruvate carboxylase (occurs in mitochondrial matrix)
Where are the only places glucose 6 phosphatase is present?
-epithelial cells of sm intestine
What affects fructose 1,6 bisphosphatase?
-stim by citrate
-inhibited by fructose 2,6 bisphosphate, AMP
Why do ppl w/ galactosemia get cataracts?
aldolase reductase converts galactose into galactitol, which builds up in eyes
What enzyme converts fructose 1 P into DHAP and glyceraldehyde?
What are the main products of pentose phosphate shunt?
-ribose 5 P
How long can liver glycogen stores last?
What disease is caused by deficiency of glycosyl 4:6 transferase (glycogen branching enzyme)?
Andersen's (Type 4) - death from liver cirrhosis
What 2 diseases are caused by glycogen phosporylase deficiency (glycogenolysis)?
-McArdle (Type 5) - muscle cramps/pain
-Hers (Type 6) - affects liver, milder than type 1
What disease is caused by glucose 6 phosphatase deficiency?
von Gierke (Type 1) - hepatomegaly, hypoglycemia, lactic acidosis, ketosis, hyperuricemia
(enzyme only present in liver)
What is Pompe disease (type 2)?
-cause: deficiency in alpha 1,4 glucosidase
-death from heart failure
What is Cori disease?
-cause: deficiency in glycogen debranching enzymes (transferase, alpha1,6glucosidase)
-like type 1 but milder
What is Tarui disease?
-cause: PFK deficiency
-problems w/ muscles and RBC
What is type 8 glycogen storage disease?
-cause: phosphorylase kinase deficiency (glycogen synthase always active; glycogen phosphorylase never active)
-mild hepatomegaly and hypoglycemia
What protein carries long chain FAs in blood?
What enzyme activates FAs?
fatty acyl CoA synthetase attaches them to CoA to make fatty acyl CoAs
What happens in pyruvate kinase deficiency?
-only affects RBCs --> hemolytic anemia
-tx: splenectomy, transfusions, iron chelation
What happens in pyruvate carboxylase deficiency?
-build up of pyruvate, lactate
-symptoms: hypoglycemia, lactic acidosis, neuro dysfunc, devo delay
-3 types: Type A (infantile), Type B (severe, neonatal), Type C (mild)
What happens in PDH deficiency?
-ATP is reduced, lactate accumulates --> neuro problems
-metabolic form: overwhelming lactic acidosis
-chronic form: profound psychomotor retardation
-X linked form: affects E1alpha subunit
-tx: ketogenic diet, thiamin supplement
What happens in MELAS?
-mutation in tRNA Leu
What happens in Leber Hereditary Optic Neuropathy?
-mutation in Complex 1 of ox phos
-late onset blindness, optic nerve damage
What happens in MERRF?
-mutation in tRNA Lys
-progressive myoclonic epilepsy, progressive dementia
-tx: CoQ and carnitine attempted
What happens in Leigh disease?
-mutation in Complex 1 or 4
-movement disorders, dystonia, MR
-X linked form exists
What happens in MCAD deficiency?
-intermittent hypoketotic hypoglycemia
-tx: high carb diet
-frequent cause of SIDS
What happens in Jamaican vomiting sickness?
-short and medium acyl CoA dehydrogenases inhibited after ingestion of hypoglycin (toxin)
-severe hypoglycemia, often fatal
What happens in CPT 2 deficiency?
-characterized by episodes of myoglobinuria
-3 types: Adult (mild), infantile (severe, multisys), neonatal (lethal)
-tx: triheptanoin, carnitine supplement
What happens in propionic acidemia?
-mech: defect in propionyl CoA carboxylase (converts propionyl CoA into methylmalonyl CoA)
-symptoms: metabolic acidosis, devo delay, MR, hypoglycemia, hypotonia, hyperammonemia
-tx: low protein diet, bicarb
What happens in methylmalonic aciduria?
-mech: defect in methylmalonyl CoA mutase (converts methylmalonyl CoA to succinyl CoA)
-symptoms: metabolic acidosis, FTT, coma, seizures, MR, hyperammonemia
-tx: restrict branched AAs in diet, Vit B12 and carnitine supplement
What diseases fall under Zellweger Spectrum Disorder?
-Zellweger syndrome (most severe)
-infantile Refsum disease
What goes wrong in Zellweger syndrome?
What goes wrong in ALD?
defect in peroxisomal VLCFA transporter --> build up of VLCFAs
What goes wrong in Refsum disease?
defect in alpha oxid enzymes --> buildup of branched FAs
What's X linked ALD?
-cause: defect in ABCD1 gene --> VLCFA accumulation
-2 types: childhood cerebral (most severe), AMN (gradually progressive)
What happens in Hartnup disease?
-cause: defect in neutral/aromatic AA transport sys
-symptoms: resemble pellagra
-dx: indoles and serotonin in urine
-tx: niacin supplement
What happens in cystinuria?
-cause: defect in absorption of Lys, Arg, Ornithine, Cys
-symptoms: cystine stones in kidneys and bladder, infections
-tx: fluids, penicillamine
What is glutathionuria?
-defect in gammaGGT (converts AA into gamma-glutamyl AA or cysteinylglycine)
-symptoms: hemolytic anemia, MR, peripheral neuropathy, ataxia
-dx: GSH in urine, blood
What is oxoprolinuria?
-defect in GSH synthetase, glutamylcysteine synthetase, or 5-oxoprolinase
-symptoms: acidosis, hemolytic anemia, jaundice
-dx: mass spec for 5-oxoproline
When would aminotransferases appear in serum?
What is the rate limiting enzyme of urea cycle?
CPS1 (only in liver)
What is citrullinemia type 1?
-defect: mutation in argininosuccinate synthase (converts citrulline to argininosuccinate) --> NH3 accumulates
-symptoms: seizures, ataxia
What is citrullinemia type 2?
-defect: solute carrier family 25 gene (shuttles citrulline from mitochondria to cytosol) --> NH3 build up
-primarily affects ppl of East Asian and Middle Eastern descent
What happens in hyperammonemia?
-dx: high levels of organic acid, AA, orotic acid in urine
-tx: restrict protein in diet, sodium benzoate, sodium phenylacetate
What happens in argininemia?
-defect in arginase (converts arginine into ornithine) --> Arg and NH3 buildup
-symptoms: poor growth, spasiticity, devo delay --> seizures, coma
-dx: blood test for NH3 and Arg, orotic acid in urine
-tx: low protein diet
What happens in argininosuccinicaciduria?
-defect in argininosuccinate lyase (converts argininosuccinate into Arg) --> NH3 buildup
-symptoms: anorexia, coma
-dx: measure NH3 level (blood)
-tx: hemodialysis, IV Arg, low protein diet
What do lyases do?
cleave covalent bonds w/o hydrolysis
Where are coenzymes bound?
at active site
What is max velocity of rxn according to Michaelis Menton kinetics?
Vmax = kcat [E]
What does small value of Km mean?
enzyme has high affinity for substrate
What is the x-int on a Lineweaver Burk plot?
What is the y-int on a Lineweaver Burk plot?
What is the slope of a Lineweaver Burk plot?
Km / Vmax
What does it mean if protein is partially complete?
maintains life but not growth
What are the measures of protein quality?
-net protein utilization
-protein efficiency ratio
What are the 3 types of fat in our diet?
1) glycerides (TGs)
3) sterols (cholesterol)
What is the RDA?
amt of various nutrients that will provide satisfactory levels of nutrients for 97.5% of ppl in designated groups ID'ed by age and sex
What is Estimated Avg Requirement?
nutrient intake value estimated to meet needs of 50% of ppl in specific age/gender group
What is Adequate Intake?
amt that appears to sustain good health in group of ppl
What is Tolerable Upper Intake Level?
highest level of nutrient likely to pose no risk of adverse effects to 98% of pop