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Biochem - metabolism Flashcards

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1
Q

Metabolism that happens specifically in mitochondria

A 
Fatty acid oxidation
acetyl-Coa production
TCA cycle
oxidative phosphorylation
ketogenesis
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2
Q

ATP production in malate-aspartate shuttle vs. G3P shuttle

A

Electrons moved to ETC b/c NADH can’t cross membrane

Malate-aspartate shuttle: utilizes malate, creates 32 ATP (heart, liver)

G3P shuttle: utilizes G3P, creates 30 ATP since electrons delivered directly to complex 2 (skeletal muscle)

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3
Q

Key enzymes in glycolysis

A

Hexokinase/glucokinase

PFK-1 (incr. by F26BP)

Pyruvate kinase

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4
Q

Regulation by F26BP

A

incr. F26BP = more glycolysis, less gluconeogenesis

less F26BP = less glycolysis

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5
Q

Two complexes in glycolysis and TCA cycle that are similar

A

Pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase

use same cofactors, similar substrates and actions

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6
Q

PDH complex deficiency

A

X-linked, causes pyruvate shunting to lactate and alanine starting in infancy

tx: incr. lysine/leucine intake! ketogenic nutrients/high fat content

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7
Q

Four possible endpoints for pyruvate

A
  1. ) alanine: ALT, B6
  2. ) oxaloacetate: pyruvate carboxylase, biotin
  3. ) acetyl-CoA: PDH, B1/2/3/5
  4. ) lactate: LDH, B3
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8
Q

ETC inhibitors

A

decr. proton gradient

cyanide, carbon monoxide, antimycin A, rotenone

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9
Q

Uncoupling agents

A

Disconnects ETC from O2 consumption

Generates free heat

2,4-dinitrophenol (weight loss), aspirin, thermogenin

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10
Q

Four main gluconeogenesis enzymes

A

Pyruvate carboxylase (makes oxaloacetate)
PEP carboxykinase (OAA to PEP)
Fructose-1,6-bisphosphatase
Glucose-6-phosphatase

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11
Q

Odd-chain fatty acids

A

produce 1 propionyl-CoA, which enters TCA, then gluconeogenesis, thus a source of glucose

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12
Q

Uses of NADPH

A

glutathione reduction in RBCs

fatty acid and cholesterol/steroid synthesis

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13
Q

Location of HMP shunt

A

RBCs (glutathione reduction

lactating mammary glands, liver, adrenal cortex (fatty acid/steroid synthesis)

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14
Q

G6P DH deficiency

A

decr. NADPH in RBCs

hemolysis precipitated by oxidizing agents or infections (from inflammatory response)

random: incr. malarial resistance

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15
Q

Fructokinase vs. aldolase B deficiency

A

Essential fructosuria - asx

Fructose intolerance - incr. F-1-P, decr. free PO4, decr. GNG. Sx present after sugar consumption (jaundice, cirrhosis, vomiting), incr. fructose in urine

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16
Q

Galactokinase vs. galactose-1-phosphate uridyltransferase deficiency

A

Galactokinase deficiency - mild condition, infantile cataracts

Classic galactosemia - failure to thrive, jaundice, hepatomegaly, ID, E. coli sepsis

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17
Q

Enzymes in sorbitol metabolism

A

Aldose reducatase: glucose to sorbitol

Sorbitol dehydrogenase: sorbitol to fructose

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18
Q

Aldose reductase only locations

A

Schwann cells, retina, kidneys, lens

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19
Q

Findings in lactase deficiency

A

Stool: decr. in pH

Breath: incr. H content

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20
Q

Urea cycle key steps

A

Carbamoyl phosphate: in mito, converts CO2 + NH3 to carbamoyl phosphate
OTC: combines CP with ornithine to make citrulline
Citrulline + aspartate/ATP = argininosuccinate
Loss of fumarate = arginine
Arginase makes ornithine again! This is loss of UREA

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21
Q

Components of urea

A

1 NH3
1 CO2
1 Aspartate

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22
Q

Path of ammonia from amino acids to excretion

A

Muscle: amino acids –> glutamate –> alanine

Cori or Cahill cycle: muscle to liver (requires alanine and lactate)

Liver: alanine –> glutamate –> urea

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23
Q

Urea cycle deficiencies

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A

N-acetylglutamate synthase deficiency: leads to hyperammonemia (required cofactor for carbamoyl phosphate synthetase)

OTC deficiency: X-linked recessive, look for orotic aciduria w/o megaloblastic anemia

24
Q

Defects in amino acid metabolism

Study These Flashcards
A 
Phenylketonuria
Maple syrup urine disease
Alkaptonuria
Homocystinuria
Cystinuria
25
Intellectual disability, seizures, fair skin, musty body odor
Phenylketonuria - decr. phenylalanine hydroxylase (decr. Phe to Tyr) tx: tyrosine supplementation, avoid aspartame (Phe)
26
Severe CNS defects, death, urine smells like burnt sugar
Maple syrup urine disease - blocked degradation of branched amino acids (isoleucine, leucine, valine) decr. alpha-ketoacid dehydrogenase tx: thiamine supplementation and restrict isoleucine, leucine, valine in diet
27
Dark connective tissue, brown sclerae, urine turns black on expsoure to air
Alkaptonuria - def. of homogentisate oxidase in the degradative pathway of tyrosine to fumarate Homogentisic acid accumulates in tissues
28
Osteoporosis, marfanoid habitus, kyphosis, lens subluxation
Homocystinuria - - cystathione synthase (B6 enzyme) deficiency (leads to decr. cysteine and incr. methionine) - - homocysteine methyltransferase (B12 enzyme) deficiency (leads to decr. methionine)
29
Recurrent hexagonal kidney stones, positive urinary cyanide-nitroprusside test
Cystinuria - defect in renal PCT/intestinal reabsorption of Cysteine, Ornitihine, Lysine, Arginine tx: potassium citrate/acetazolomide, chelating agents
30
Homocyteine products
Homocysteine methyltransferase - converts to methionine using B12 Cystathione synthase - converts to cystathione using B6
31
Stimulators of glycogenolysis
Glucagon (incr. cAMP, PKA) | Epinephrine alpha and beta receptors (incr. cAMP, PKA)
32
Stimulators of glycogen synthesis
Insulin (tyrosine kinase receptor, phosphorylation of glycogen synthase)
33
Glycogen breakdown
Muscle - glycogen to G6P (uses phosphoglucomutase) to enter glycolysis Liver - Glycogen phosphorylase, debranching enzymes cleaves off in orderly pattern
34
Glycogen storage diseases
Type I: Von gierke (glucose-6-phosphatase) Type II: Pompe (acid maltase) Type III: Cori (debranching) Type IV: McArdle (skeletal muscle glycogen phosphorylase)
35
Severe fasting hypoglycemia, incr. glycogen in liver (hepatomegaly), incr. TGs, lactic acidemia
Von gierke - glucose-6-phosphatase tx: frequent oral glucose/cornstarch, avoid fructose/galactose
36
Hypertrophic cardiomyopathy, cardiomegaly, exercise intolerance, early death
Pompe - acid maltase Pompe trashes the pump
37
Fasting hypoglycemia with normal lactate levels
Cori - debranching enzyme Gluconeogenesis intact
38
Painful muscle cramps, myoglobinuria, arrhythmia from electrolyte disturbances
McArdle (skeletal muscle phosphorylase) Blood glucose levels are unaffected McArdle = muscle Tx: B6 supplementation
39
HSM, pancytopenia, aseptic necrosis of femur, bone crises, Gaucher cell (lipid-laden macs, tissue paper)
Gaucher disease - glucocerebridase accum of glucocerebroside
40
Progressive neurogeneration, foam cells, cherry-red macula, HSM
Niemann-Pick disease - sphingomyelinase accum of sphingomyelin
41
Progessive neurodegeneration, developmental delay, cherry-red macula, onion skin lysosomes, NO HSM
Tay-Sachs disease - hexosiaminidase A NOTE: NO HEPATOMEGALY!
42
Optic atrophy, globoid cells, peripheral neuropathy
Krabbe disease - galactocerebridase
43
Hurler vs. Hunter syndrome
Mucopolysaccharides Hurler - corneal clouding, airway obstruction Hunter - no corneal clouding, aggressive behavior
44
Citrate shuttle
used in fatty acid synthesis to move citrate from mitochondria to the cytosol sytrate = synthesis
45
Carnitine shuttle
used to move fatty acyl-CoA from the cytosol to the mitochondria carnitine = fatty acyl carnage
46
Minor illness leading sudden death, liver dysfunction, present in infancy or early childhood with vomiting
MCAD deficiency accumulation of 8 to 10 carbon fatty acyl carnitines in the blood leads to hypoketotic hypoglycemia***
47
Causes of ketogenesis
prolonged starvation or diabetes - depletion of oxaloacetate for gluconeogenesis alcoholism - excess NADH shunts oxaloacetate to malate
48
Fat sources for gluconeogenesis
Odd-chain FFAs Adipose tissue glycerol
49
LPP that mediates remnant uptake (extra remnantsq
Apo-E
50
LPP that activates LCAT
Apo-A1
51
LPP that serve as lipoprotein lipase cofactor
Apo-C2
52
LPP that mediates chylomicron secretion
Apo-B48
53
LPP that binds LDL receptor
Apo-B100
54
Xanthomas, pancreatitis, HSM, creamy layer in supernatant
Type I hyperchylomicronemia lipoprotein lipase deficiency
55
Accelerated atherosclerosis, tendon xanthoma, corneal arcus
Type II hypercholesterolemia absent/defective LDL receptor
56
Hepatic overproduction of VLDL
Type IV hypertriglyceridemia

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