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step 1 - biochem > metabolism > Flashcards

metabolism Flashcards

1
Q

what are the 3 pathways of ethanol metabolism?

A

1) cytosolic: alcohol DH and acetaldehyde DH
2) microsomal: CYP2E1
3) peroxisomal: catalase

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2
Q

limiting reagent in ethanol metabolism?

A

NAD+

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3
Q

what are the downstream effects of ETOH metab?

A

1ary: increased NADH/NAD+ ratio –>
lactic acidosis (pyruvate –> lactate)
fasting hypoglycemia (OAA –> malate - prevents gluconeo)
hepatosteatosis (DHAP –> G3P)
increased use of AcCoA for ketogenesis and lipogenesis

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4
Q

what metabolic processes happen in the mitochondria?

A 
FA oxidation
AcCoA production
TCA cycle
OxPhos
ketogenesis
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5
Q

what metabolic processes happen in the cytoplasm?

A 
glycolysis
FA synthesis
HMP shunt
protein synthesis (RER)
steroid synthesis (SER)
cholesterol synthesis
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6
Q

what metabolic processes happen in both mito and cytoplasm?

A

heme synthesis
urea cycle
gluconeogenesis

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7
Q

rate determining enzyme of glycolysis?

A

PFK!

+: AMP, F26BP
-: ATP, citrate

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8
Q

rate determining enzyme of gluconeo?

A

F16BPase

+: ATP, AcCoA
-: AMP, F26BP

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9
Q

rate determining enzyme of TCA?

A

isocitrate DH

+: ADP
-: ATP, NADH

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10
Q

rate determining enzyme of glycogenesis?

A

glycogen synthase

+: G6P, insulin, cortisol
-: epi, glucagon

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11
Q

rate determining enzyme of glycogenolysis?

A

glycogen phosphorylase

+: epi, glucagon, AMP
-: G6P, insulin, ATP

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12
Q

rate determining enzyme of HMP shunt?

A

G6PD

+: NADP
-: NADPH

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13
Q

rate determining enzyme of pyrimidine synth?

A

carbamoyl P synthetase II

+ ATP
- UTP

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14
Q

rate determining enzyme of purine synth?

A

glutamine-PRPP amidotransferase

  • AMP, IMP, GMP
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15
Q

rate determining enzyme of urea cycle?

A

carbamoyl P synthetase I

+ N-acetyl glutamate

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16
Q

rate determining enzyme of FA synthesis?

A

AcCoA carboxylase

+ insulin, citrate
- glucagon, palmitoyl-CoA

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17
Q

rate determining enzyme of FA oxidation?

A

carnitine acyltransferase I

  • malonyl CoA
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18
Q

rate determining enzyme of ketogenesis?

A

HMG CoA synthase

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19
Q

rate determining enzyme of cholesterol synthesis?

A

HMG CoA reductase

+ insulin, thyroxine
- glucagon, cholesterol

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20
Q

ATP prod in aerobic metabolism vs anaerobic?

A

aerobic (malate-asp shuttle, heart/liver) - 32
aerobic (G3P shuttle, muscle) - 30
anaerobic - 2
arsenic - 0

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21
Q

what do CoA and lipoamide carry?

A

acyl groups

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22
Q

what does biotin carry?

A

CO2 - carboxylation rxns

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23
Q

what do THFs carry?

A

1-carbon units

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24
Q

what does SAM carry?

A

methyl groups

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25
Q

what does TTP carry?

A

aldehydes

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26
Q

what types of processes is NAD+ used in?

A

catabolic processes - carrying reducing equivalents

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27
Q

what types of processes is NADPH used in?

A

anabolic
respiratory burst
CYP450
glutathione reductase

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28
Q

where is hexokinase found?

A

most tissues except liver and pancreatic beta cells

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29
Q

where is glucokinase found

A

liver, beta cells of pancreas

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30
Q

which of hexo/glucokinase is induced by insulin?

A

glucokinase

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31
Q

which of hexo/glucokinase is inhibited by G6P?

A

hexokinase

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32
Q

what cofactors are needed by pyruvate DH (and a-KG DH)?

A
  1. TPP - thiamine/B1
  2. FAD - riboflavin/B2
  3. NAD - niacin/B3
  4. CoA - pantothenic acid/B5
  5. lipoic acid (inhibited by arsenic)
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33
Q

increased serum alanine in infancy, lactic acidosis, neurologic defects?

A

pyruvate DH deficiency - X-linked
pyruvate builds up –> lactate and alanine

tx: increase ketogenic intake (lysine, leucine)

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34
Q

what cofactor does alanine aminotransferase need?

A

B6 (pyridoxine)

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35
Q

what cofactor does lactic acid DH need?

A

B3 (niacin)

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36
Q

where is anaerobic metabolism the major pathway?

A 
RBC
WBC
kidney medulla
lens
testes
cornea
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37
Q

what is the order of products of the TCA?

A 
citrate
isocitrate
a-KG
succinyl CoA
succinate
fumarate
malate
OAA
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38
Q

which complex of the ETC does rotenone inhibit?

A

complex I

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39
Q

which complex of the ETC does antimycin A inhibit?

A

complex III

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40
Q

which complex of the ETC do cyanide and CO inhibit?

A

complex IV

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41
Q

which complex of the ETC does oligomycin inhibit?

A

complex V (ATP synthase)

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42
Q

which agents are ETC uncoupling agents?

A

2,4 Dinitrophenol
aspirin
thermogenin

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43
Q

which are the irreversible enzymes of gluconeogenesis?

A

pyruvate carboxylase (mitochondria)
PEP carboxykinase
F16BPase
G6Pase (ER)

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44
Q

which are the enzymes of the oxidative/irreversible portion of the HMP shunt?

A

G6PD!

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45
Q

which are the enzymes of the nonoxidative/reversible portion of the HMP shunt? what cofactor do they need?

A

transketolases
phosphopentose isomerase

require THIAMINE!

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46
Q

fructose in blood and urine, asx/mild?

A

essential fructosuria - AR

defect in fructokinase

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47
Q

hypoglycemia, jaundice, cirrhosis, vomiting; sx after fruit/juice/honey, negative urine dipstick but reducing substance in urine?

A

fructose intolerance - AR
defect in aldolase B
F1P accumulates in cells, available P decreases –> no glycogenolysis or gluconeogenesis

tx: no fructose or sucrose in diet

48
Q

infantile cataracts, no other sx?

A

galactokinase deficiency - AR

mild, accumulation of galactitol with ingestion of galactose

49
Q

infantile cataracts, intellectual disability, FTT, jaundice, hepatomegaly, E. coli sepsis?

A

classic galactosemia - AR
absence of gal-1-P uridyltransferase

tx: no galactose or lactose in diet

50
Q

which tissues do not have sorbitol DH?

A

schwann cells, retina, kidneys, lens

51
Q

cause of primary lactase deficiency?

A

absence of lactase persistent allele
age-dependent decline following childhood
Asians, Africans, Native Americans

52
Q

causes of 2ary lactase deficiency?

A

loss of brush border: gastroenteritis, autoimmune

53
Q

which are the essential AAs?

A

LEUcy and LYSa MET VAL on HIS TRiP THRough the IsLE of PHoEnix

54
Q

which are the ketogenic AAs?

A

leu

lys

55
Q

which are the glucogenic AAs?

A

met
val
his

56
Q

which are the acidic AAs?

A

asp

glu

57
Q

which are the basic AAs?

A

HAL is a basic guy

his
arg
lys

58
Q

which AAs are required during growth?

A

Arg

His

59
Q

which AAs are in histones?

A

Arg

Lys

60
Q

what is the order of products/substrates in the urea cycle?

A

Ordinarily Careless Crappers Are Also Frivolous About Urination

ornithine
\+ carbamoyl phosphate
citrulline
\+ aspartate
argininosuccinate
- fumarate
arginine
- urea
61
Q

what is the cofactor for transamination to a-KG/glutamate?

A

B6 (pyridoxine)

62
Q

what is the Cahill cycle?

A

transfer of ammonia via alanine

  • transamination from glu –> ala in mm
  • ala travels to liver
  • transamination from ala –> glu –> urea cycle
63
Q

what is the Cori cycle?

A
  • glucose –> pyruvate –> lactate in mm
  • reverse in liver

related to Cahill cycle - ammonia transfer from mm to liver

64
Q

neonate with poorly regulated respiration and body temp, poor feeding, developmental delay, intellectual disability?

A

N-acetylglutamate synthase deficiency (or carbamoyl phosphate synthetase I deficiency)

65
Q

hyperammonemia symptoms, increased orotic acid in blood and urine, decreased BUN, no megaloblastic anemia?

A

OTC deficiency - XLR
excess carbamoyl P converted to orotic acid

    • orotic aciduria: megaloblastic anemia
    • other urea cycle deficits: AR
66
Q

derivatives of trp, and cofactors needed?

A

niacin - needs B6

serotonin/melatonin - needs B6 and BH4

67
Q

derivatives of his, and cofactors needed?

A

histamine - needs B6

68
Q

derivatives of gly, and cofactors needed?

A

porphyrin –> heme, needs B6

69
Q

derivatives of glu, and cofactors needed?

A

GABA - needs B6

glutathione

70
Q

derivatives of arginine, and cofactors needed?

A

creatine
urea
NO - B6 needed

71
Q

intellectual disability, growth retardation, seizures, fair skin, eczema, MUSTY body odor?

A

PKU - AR
defect in phe hydroxylase or decreased BH4 cofactor
avoid aspartame, decrease phenylalanine, increase tyrosine
BH4 supplementation

72
Q

sweet urine, severe CNS defects, intellectual disability?

A

MSUD - AR
branched chain AA degradation blocked - defective a-ketoacid DH (needs thiamine as cofactor)

tx: restrict BCAAs, thiamine supplementation

73
Q

which are the branched chain AAs?

A

ILE
LEU
VAL

74
Q

black pee, dark connective tissue, brown sclerae, arthralgia?

A

alkaptonuria - AR
deficiency of homogentisate oxidase (tyr degradation pathway)
usually benign

75
Q

Marfanoid habitus, osteoporosis, kyphosis, downward lens subluxation, thrombosis, atherosclerosis?

A

homocystinuria - AR

  • cystathionine synthase deficiency (tx: dec MET, inc CYS, B12, folate)
  • decreased cyst synth affinity for PLP (tx: inc B6 and CYS)
  • homocysteine methyltransferase deficiency (tx: inc MET)
76
Q

hexagonal urinary stones, + urinary cyanide nitroprusside test?

A

cystinuria - AR
defect of AA transport - increased excretion of COLA

tx: alkalinize urine (K citrate, acetazolamide)
chelate with penicillamine
hydrate

77
Q

glycogen regulation by glu/epi

A

1) glu –> glucagon rcptr (liver), epi–> alpha (liver) and beta (liver and mm) rcptr
2) cAMP increase and Ca increase (from epi at alpha)
3) PKA activated from cAMP
4) PKA and Ca activate glycogen phosphorylase kinase
5) glycogen phosphorylase activated
6) PKA –> glycogen synthase inactivated

78
Q

glycogen regulation by insulin

A

1) insulin binds tyr-kinase dimer rcptr (liver and mm)
2) downstream activation of protein phosphatase and glycogen synthase
3) protein phosphatase activates glycogen synthase and deactivates glycogen phosphorylase

79
Q

what types of bonds are in the branches of glycogen?

A

alpha 1,6

80
Q

what types of bonds are in the linkages of glycogen?

A

alpha 1,4

81
Q

what enzymes are involved in glycogenolysis?

A

1) glycogen phosphorylase: active until 4 units remaining on branch (“limit dextrin”)
2) 4-a-D-glucanotransferase moves 3 units branch –> linkage
3) a-1,6-glucosidase cleaves last unit –> glucose liberated

82
Q

severe fasting hypogly, high glycogen in liver, lactate in blood, TGemia, increased uric acid, hepatomegaly?

A

VonGierke’s - type I GSD, AR
glucose-6-phosphatase deficient

tx: frequent oral glucose/cornstarch; avoid fructose and galactose

83
Q

cardiomegaly, HOCM, exercise intolerance, early death?

A

Pompe’s - type II GSD, AR
lysosomal a-1,4-glucosidase deficiency

** Pompe trashes the Pump: heart, liver, muscle

84
Q

milder VonGierke, normal blood lactate?

A

Cori - type III GSD, AR
deficient a-1,6-glucosidase

** gluconeogenesis is intact

85
Q

painful muscle cramps, myoglobinuria, arrhythmia?

A

McArdle’s - type V GSD, AR
deficient MUSCLE glycogen phosphorylase
blood glucose usually normal
tx: B6 (cofactor)

86
Q

hand/foot neuropathy, angiokeratomas, CV/renal dz?

A

Fabry disease, XR
deficient a-galactosidase A
accumulation of ceramide trihexoside

87
Q

HSM, pancytopenia, osteoporosis, aseptic necrosis of femur, lipid-laden macrophages, bone crises?

A

Gaucher dz - AR
deficient glucocerebrosidase
accumulation of glucocerebroside

** tx: recombinant glucocerebrosidase

88
Q

neurodegeneration, HSM, foam cells, cherry-red spot?

A

Niemann-Pick, AR
deficient sphingomyelinase
accumulation of sphingomyelin

89
Q

neurodegeneration, NO HSM, cherry red spot, onion skin lysosomes?

A

Tay Sachs, AR
deficient hexosaminidase A
accumulation of GM2 ganglioside

90
Q

peripheral neuropathy, developmental delay, optic atrophy, globoid cells?

A

Krabbe disease, AR
deficient galactocerebrosidase
accumulation of galactocerebroside, psychosine

91
Q

central and peripheral demyelination with ataxia and dementia?

A

metachromic leukodystrophy, AR
deficient arylsulfatase A
accumulation of cerebroside sulfate

92
Q

developmental delay, gargoylism, airway obstruction, corneal clouding, HSM?

A

Hurler dz, AR
deficient a-L-iduronidase
accumulation of heparan sulfate and dermatan sulfate

93
Q

like Hurler but with aggressive behavior and no corneal clouding?

A

Hunter dx, XLR
deficient iduronate sulfatase
accumulation of heparan sulfate and dermatan sulfate

94
Q

weakness, hypotonia, hypoketotic hypoglycemia?

A

systemic 1ary carnitine deficieny

defect in LCFA transport into mitochondria –> toxic accumulation

95
Q

which are the essential FAs?

A

linoleate

alpha-linolenate

96
Q

citrate shuttle is required for which process?

A

FA synthesis (transport from mito to cytosol)

97
Q

carnitine shuttle is required for which process?

A

FA degradation (transport from cytosol to mito)

98
Q

infancy/childhood with vom, lethargy, sz, coma, liver dysfunction, hypoketotic hypoglycemia, 8-10-C FA-carnitines in blood?

A

medium-chain acyl-coA DH deficiency, AR
minor illness –> sudden death
tx: AVOID FASTING

99
Q

main source of blood glucose in days 1-3 of starvation?

A

glycogen depleted after day 1

hepatic glycogenolysis, adipose FFA, muscle/liver use of FFAs, hepatic gluconeogenesis –> maintain blood glucose

100
Q

main source of energy after day 3 of starvation?

A

adipose stores

KBs main source for brain

101
Q

can RBCs use ketones for energy?

A

NO! don’t have mitochondria

102
Q

what are products of cholesterol?

A

bile acids
steroids
vit D

103
Q

what does pancreatic lipase do?

A

degrades dietary TGs in small intestine

104
Q

what does LPL do?

A

produced by adipose cells, found in vascular endothelium

degrades TGs in CMs and BLDLs

105
Q

what does HL do?

A

hepatic

degrades TGs in IDL in periphery

106
Q

what does HSL do?

A

degrades TGs stored in adipocytes

107
Q

what does LCAT do?

A

catalyzes esterification of cholesterol –> load HDL with cholesterol from peripheral tissues
activated by apoA

108
Q

what does CETP do?

A

mediates transfer of cholesterol esters from HDL to other lipoproteins

109
Q

what do chylomicrons do?

A

dietary TG–> peripheral tissues
chol –> liver (via CM remnants)
secreted by intestinal epithelial cells

110
Q

what does VLDL do?

A

delivers hepatic TG to peripheral tissue

111
Q

what does IDL do?

A

delivers TGs and chol to liver

112
Q

what does LDL do?

A

delivers hepatic chol to periphery

taken up via receptor-mediated endocytosis (apoB100 binds LDL receptor)

113
Q

what does HDL do?

A

chol transport from periphery to liver
repository for apoC and apoE –> CM and VLDL
secreted by liver and gut

**alcohol causes increased synthesis of HDL

114
Q

pancreatitis, HSM, eruptive/pruritic xanthomas W/O atherosclerosis, creamy supernatant?

A

hyperchylomicronemia, AR

LPL deficiency or altered apoCII

115
Q

accelerated atherosclerosis (MI <20yo), tendon xanthomas, corneal arcus?

A

familial hypercholesterolemia, AD
absent/defective LDL receptors
heterozygotes chol ~300, homozygotes ~700+

116
Q

very very high TGs?

A

hypertriglyceridemia, AD
hepatic overproduction of VLDL

** TGs>1000 –> pancreatitis

step 1 - biochem (5 decks)

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