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Biochem > more metabolism > Flashcards

more metabolism Flashcards

1
Q

what form of AAs are found in proteins?

A

L-form

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2
Q

essential AAs

A

must come from diet.

Glucogenic: Val, Met, His, Arg.
Ketogenic: Lys, Leu.
Both: Ile, Phe, Thr, Trp, Tyr

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3
Q

acidic AAs

A

Asp and Glu - neg charge at body pH

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4
Q

basic AAs

A

His, Lys, Arg.

Arg is most basic.
His has no charge at body pH.

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5
Q

which AAs are required during periods of growth?

A

His, Arg

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6
Q

which AAs are increased in histones?

A

Arg, Lys - bind neg charged DNA

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7
Q

AA catabolism yields?

A

common metabolites (pyruvate, acetyl CoA) that are used as fuel.

excess nitrogen (NH4+) that must be excreted.

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8
Q

how is excess NH4+ from AA catabolism excreted?

A

converted to UREA,

excreted by kidneys

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9
Q

contributors to urea structure

A
  1. NH4+
  2. CO2
  3. aspartate
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10
Q

urea cycle intermediates (in order)

A 
Ornithine.
Carbamoyl phosphate.
Citrulline.
Aspartate.
Argininosuccinate.
Fumarate.
Arginine.
Urea.

“Ordinarily Careless Crappers Are Also Frivolous About Urination”

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11
Q

hyperammonemia

A

results in excess NH4+
which depletes alpha-KG
leading to inhib of TCA cycle.

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12
Q

causes of hyperammonemia

A

acquired: liver disease.
hereditary: urea cycle enz def.

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13
Q

ammonium intoxication

A 
tremor.
slurred speech.
somnolence.
vomiting.
cerebral edema.
blurred vision.
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14
Q

TX of hyperammonemia

A
  1. limit protein in diet.
  2. benzoate or phenylbutyrate: bind AA for excretion (bypass urea cycle), thus decreasing ammonia levels.
  3. lactulose: acidify GI lumen and trap NH4+ for excretion.
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15
Q

ornithine transcarbamoylase deficiency

A

most common urea cycle d/o.
only X-linked recessive one.

interfere w/ability to eliminate ammonia.

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16
Q

presentation of OTC def

A

often evident in first few days of life but may present with late onset.

severe neuro problems.
sx of hyperammonemia.
OROTIC ACID in bld and urine.
decreased BUN (urea).

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17
Q

what happens to excess carbamoyl phosphate in OTC def?

A

converted to OROTIC ACID of pyrimidine synth pathway

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18
Q

catecholamine cofactors

A

dopa to dopamine: B6.
dopamine to NE: vit C.
NE to epi: SAM.

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19
Q

catecholamine breakdown products

A

via MAO and COMT.

dopamine: HVA.
NE: VMA.
epi: metanephrine.

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20
Q

phenylketonuria (PKU)

A

due to decreased phenylalanine hydroxylase.

auto recessive. 1:10000.

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21
Q

malignant PKU

A

due to decreased tetrahydrobiopterin (THB) cofactor

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22
Q

what AA becomes essential in PKU?

A

tyrosine

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23
Q

findings in PKU

A 
mental retardation.
growth retardation.
seizures.
fair skin.
eczema.
musty body odor.

increased phenylalanine = excess phenylketones in urine.

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24
Q

what creates musty body odor in PKU?

A

disorder of aromatic amino acid metabolism

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25
Q

phenylketones

A

phenylacetate.
phenyllactate.
phenylpyruvate.

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26
Q

PKU in newborns

A

screened for 2-3 days after birth

normal at birth due to maternal enzyme during fetal life

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27
Q

TX of PKU

A

dietary restrictions:

  1. decrease phenylalanine (in aspartame).
  2. increase tyrosine.
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28
Q

maternal PKU

A

lack of proper dietary therapy during pregnancy.

findings in infant:
microcephaly.
mental retardation.
growth retardation.
congenital heart defects.
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29
Q

alkaptonuria (ochronosis)

A

congenital deficiency of homogentisic acid oxidase - part of tyrosine degradation to fumarate.

auto recessive.
benign.

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30
Q

findings in alkaptonuria (ochronosis)

A

dark conn tissue.
brown pigmented sclera.
urine turns BLACK on prolonged exposure to air.

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31
Q

how does homogentisic acid affect cartilage?

A

toxic to it- cause debilitating arthralgias

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32
Q

albinism

A

congenital deficiency of:
1. tyrosinase: needed to synthesize melanin from tyrosine. auto recessive.

  1. defective tyrosine transporters: decreased tyrosine = decreased melanin.
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33
Q

melanocytes in albinism

A

usually NORMAL in number and location, though possible cause of albinism is lack of migration of neural crest cells

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34
Q

variable inheritance of albinism due to?

A

locus heterogeneity

vs. X-linked recessive ocular albinism

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35
Q

features of albinism

A

white hair.
blue eyes.
pink/white skin.
increased risk of skin cancer.

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36
Q

homocystinuria

A

3 auto recessive forms.

result in EXCESS HOMOCYSTEINE.

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37
Q

what AA becomes essential in homocystinuria?

A

cysteine

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38
Q

findings in homocystinuria

A 
increased homocysteine in urine.
mental retardation.
osteoporosis.
tall stature.
kyphosis.
lens subluxation (down and in).
atherosclerosis- stroke, MI**
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39
Q

homocystinuria causes

A
  1. cystathionine synthase def.
  2. decreased affinity of cystathionine synthase for pyridoxal phosphate.
  3. homocysteine methyltransferase def.
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40
Q

TX of cystathionine synthase def

A

decrease methionine.

increase cysteine, B12, folate in diet.

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41
Q

TX of decreased affinity of cystathionine synthase for pyridoxal phosphate

A

greatly increase vit B6 in diet

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42
Q

TX of homocysteine methyltransferase def

A

B12 supp (enz requires B12)

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43
Q

cystinuria

A

hereditary defect of renal tubular AA transporter for cysteine, ornithine, lysine, and arginine in PCT of kidneys.

auto recessive.

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44
Q

cystine

A

2 cysteines connected by disulfide bond

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45
Q

excess cystine in urine leads to?

A

cystine kidney stones (hexagonal crystals)- form staghorn calculi

46
Q

cystinuria TX

A

acetazolamide: alkalinize urine

47
Q

maple syrup urine disease

A

blocked degrad of branched amino acids (Ile, Leu, Val) due to decreased alpha-ketoacid dehydrogenase

“I Love Vermont MAPLE SYRUP from maple tree BRANCHES”

48
Q

what is increased in blood in maple syrup urine disease?

A

alpha-ketoacids, esp Leu

49
Q

findings in maple syrup urine disease

A 
urine smells like MAPLE SYRUP.
severe CNS defects.
MR.
dystonia.
poor feeding.
death.
50
Q

Hartnup disease

A

auto recessive defect of neutral amino acid transporters on renal and intestinal epith cells

51
Q

findings in Hartnup disease

A

tryptophan excreted in urine.
decreased absorp from gut.

PELLAGRA:
Diarrhea,
Dermatitis,
Dementia.

52
Q

glycogen branches

A

alpha 1,6 bonds

53
Q

glycogen linkages

A

alpha 1, 4 bonds

54
Q

glycogen in skel muscle

A

glycogenolysis: glycogen to G1P to G6P (cannot make glucose).

G6P rapidly metabolized during exercise.

55
Q

glycogen in hepatocytes

A

stored in liver.

undergoes glycogenolysis to maintain blood sugar at appropriate levels.

56
Q

enzymes in glycogen synth

A
  1. UDP-gluc pyrophosphorylase.
  2. glycogen synthase.
  3. branching enzyme.
57
Q

enzymes in glycogenolysis

A
  1. glycogen phosphorylase.

2. debranching enzyme.

58
Q

alpha-1,4-glucosidase

A

degrades a small amount of glycogen in lysosomes

59
Q

glycogen storage diseases

A

12 types total.
abn glycogen metabolism.
accum of glycogen in cells.

"Very Poor Carbohydrate Metabolism"
Von Gierke's.
Pompe's.
Cori's.
McArdle's.
60
Q

Von Gierke’s disease (type I)

A

glycogen storage disease.

deficient GLUCOSE-6-PHOSPHATASE.

61
Q

findings in Von Gierke’s

A

severe fasting hypoglycemia.
great increase in liver glycogen.
increase blood lactate.
hepatomegaly.

62
Q

Pompe’s disease (type II)

A

glycogen storage disease.

deficient LYSOSOMAL ALPHA-1,4-GLUCOSIDASE (ACID MALTASE).

63
Q

findings in Pompe’s

A

cardiomegaly.
systemic findings- liver, muscle.
early death.

“Pompe’s trashes the pump (heart)”

64
Q

Cori’s disease (type III)

A

glycogen storage disease.
milder form of type I with NORMAL blood lactate levels.

deficient DEBRANCHING ENZ (ALPHA-1,6-GLUCOSIDASE).

65
Q

McArdle’s disease (type V)

A

glycogen storage disease.

defecient SKELETAL MUSCLE GLYCOGEN PHOSPHORYLASE.

66
Q

findings in McArdle’s

A

increased glycogen in muscle but cannot break it down….

painful muscle cramps, myoglobinuria with strenuous exercise.

67
Q

Fabry’s disease

A

LSD: sphingolipidosis.
XR inheritance.
deficient alpha-galactosidase A.

accumulate: ceramide trihexoside.

68
Q

findings in Fabry’s

A

peripheral neuropathy of hands, feet.
angiokeratomas.
cardiovascular.
renal.

69
Q

Gaucher’s disease

A

LSD: sphingolipidosis.
AR inheritance.
deficient glucocerebrosidase.
most common LSD.

accumulate: glucocerebroside.

70
Q

findings in Gaucher’s

A

hepatosplenomegaly.
aseptic necrosis of femur.
bone crises.
pancytopenia.

GAUCHER’S CELLS: macrophages that look like crumpled tissue paper.

71
Q

Niemann-Pick disease

A

LSD: sphingolipidosis.
AR inheritance.
deficient sphingomyelinase.

accumulate: sphingomyelin.

72
Q

findings in Niemann-Pick

A

progressive neurodegeneration.
hepatosplenomegaly.
cherry-red spot on macula.
FOAM CELLS.

73
Q

Tay-Sach’s disease

A

LSD: sphingolipidosis.
AR inheritance.
deficient hexosaminidase A.

accumulate: GM2 ganglioside.

74
Q

findings in Tay-Sach’s

A

progressive neurodegeneration.
developmental delay (normal in first few months).
cherry-red spot on macula.
lysosomes with ONION SKIN.
**NO hepatosplenomegaly (vs. Niemann-Pick)

75
Q

Krabbe’s disease

A

LSD: sphingolipidosis.
AR inheritance.
deficient galactocerebrosidase.

accumulate: galactocerebroside and galactosyl sphingosine.

76
Q

findings in Krabbe’s

A

peripheral neuropathy.
developmental delay.
optic atrophy.
GLOBOID cells.

77
Q

metachromatic leukodystrophy

A

LSD: sphingolipidosis.
AR inheritance.
deficient arylsulfatase A.

accumulate cerebroside sulfate.

78
Q

findings in metachromatic leukodystrophy

A

central and peripheral demyelination with ataxia, dementia, muscle wasting

79
Q

Hurler’s syndrome

A

LSD: mucopolysaccharidosis.
AR inheritance.
deficient alpha-L-iduronidase.

accumulate: heparan sulfate, dermatan sulfate.

80
Q

findings in Hurler’s syndrome

A 
developmental delay.
GARGOYLISM.
airway obstruction.
corneal clouding.
hepatosplenomegaly.
81
Q

Hunter’s syndrome

A

LSD: mucopolysaccharidosis.
XR inheritance.
deficient iduronate sulfatase.

accumulate: heparan sulfate, dermatan sulfate.

82
Q

findings in Hunter’s

A

mild Hurler’s syndrome PLUS aggressive behavior with No corneal clouding

83
Q

carnitine deficiency

A

inability to transport LCFA into mito.

toxic accumulation results.

84
Q

features of carnitine deficiency

A

weakness.
hypotonia.
hypoketotic hypoglycemia.

85
Q

acyl CoA dehydrogenase deficiency

A

increase dicarboxylic acids.

decrease glucose, ketones.

86
Q

apo B-100

A

binds LDL receptor.

present in VLDL, IDL, LDL.

87
Q

apo B-48

A

mediates chylomicron secretion by intestine.

present in chylomicron and remnant.

88
Q

apo C-II

A

lipoprotein lipase cofactor.

present in chylo, VLDL, HDL.

89
Q

apo A-I

A

activates LCAT for chol esterification.

present in chylo and HDL.

90
Q

apo E 3, 4

A

mediate remnant uptake by liver.

present in all but LDL.

91
Q

which lipoproteins carry most chol?

A

LDL and HDL

92
Q

LDL transports chol from?

A

liver to tissues

93
Q

HDL transports chol from?

A

periphery to liver

94
Q

chylomicron

A

delivers dietary TGs to peripheral tissue.

also chol to liver via remnants, which are depleted of most TGs.

95
Q

what cells secrete chylomicrons?

A

intestinal epith cells

96
Q

VLDL

A

delivers hepatic TGs to peripheral tissues.

97
Q

what secretes VLDL?

A

liver

98
Q

IDL

A

formed as part of VLDL degrad.

delivers TGs and chol to liver where they are degraded to LDL.

99
Q

LDL

A

delivers hepatic chol to peripheral tissue.

100
Q

how is LDL formed?

A

lipoprotein lipase modification of VLDL in periphery

101
Q

how is LDL taken up by peripheral target cells?

A

receptor-mediated endocytosis

102
Q

HDL

A

mediates REVERSE chol transport from periphery to liver.

acts as repository for apoC and aloe whch are needed for chylomicron and VLDL metabolism.

103
Q

what secretes HDL?

A

liver and intestine

104
Q

familial dyslipidemia type I

A

hyper-CHYLOMICRONS.
elevated blood levels of TG and chol.
due to LPL deficiency or altered apoC-II.

105
Q

findings in familial dyslipidemia type I

A

hyper-CHYLOMICRONS.

pancreatitis.
hepatosplenomegaly.
eruptive/pruritic xanthomas but NO INCREASED RISK for atherosclerosis.

106
Q

familial dyslipidemia type IIa

A

familial hypercholesterolemia.
HIGH LDL.
elevated bld levels of chol.

auto dom.
absent or decreased LDL receptors in hepatocytes.

107
Q

findings in familial dyslipidemia type IIa

A

familial hypercholesterolemia.

accelerated atherosclerosis.
early CAD.
tendon (achilles) xanthomas.
corneal arcus.

108
Q

familial dyslipidemia type IV

A

hypertriglyceridemia.
HIGH VLDL.
increased bld levels of TG.
due to hepatic overproduction of VLDL.

causes PANCREATITIS.

109
Q

abetalipoproteinemia

A

hereditary inability to make lipoproteins due to deficiencies in apoB-100 and B-48.

auto rec MTP mutation.
enterocytes unable to export lipoproteins and FFA.

110
Q

findings in abetalipoproteinemia

A 
appear in first few months of life.
failure to thrive.
steatorrhea.
acanthocytosis (spur cells).
ataxia.
night blindness.
111
Q

abetalipoproteinemia intestinal BX

A

accumulation w/in enterocytes due to inability to export absorbed lipid as chylomicrons

Biochem (7 decks)

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