Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Boards > Enzymes and Biochem principles > Flashcards

Enzymes and Biochem principles Flashcards

1
Q

UDP-glucuronyl transferase

A

conjugates bilirubin by adding glucuronyl group

  • mild decrease = Gilbert
  • absent = Crigler-Najjar Type 1
  • mutated = Crigler-Najjar Type 2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Rate limiting step in pyrimidine synthesis is catalyzed by which enzyme

A

Carbamoyl phosphate synthetase II

-converts glutamine + CO2 + ATP into carbamoyl phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Autosomal recessive defect in UMP synthase

A

Orotic aciduria

FTT, developmental delay, megaloblastic anemia that doesn’t respond to folate or B12

  • no high ammonia
  • orotic acid in urine
  • tx with uridine monophosphate supplementation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Rxn catalyzed by UMP synthase

A

orotic acid –> UMP

-needed or pyrimidine synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Disease resulting from absent HGPRT

A

Lesch-Nyhan

  • X-linked
  • excess uric acid production
  • intellectual disability, hyperuricemia (orange “sand” in diaper), gout, dystonia, aggression, self-mutilation
  • tx = allopurinol or febuxostat for gout
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Rxns catalyzed by HGPRT

A

hypoxanthine –> IMP, guanine –> GMP

-purine salvage pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Rxn catalyzed by Adenosine deaminase

A

degradation of adenosine and deoxyadenosine in purine salvage pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Result of a deficiency in ADA

A

SCID - autosomal recessive

-due to increase in dATP which is toxic to lymphocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Rate limiting step in purine synthesis is catalyzed by which enzyme

A

Glutamine PRPP amidotransferase

PRPP –> IMP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Disease due to defect in mismatch repair

A

Lynch syndrome (HNPCC)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Disease due to defect in nonhomologous end joining

A

ataxia telangiectasia (also fanconi anemia)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Disease due to defect in nucleotide excision repair

A

Xeroderma pigmentosum (can’t fix thymidine dimers - very sensitive to sun)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Function of DNA pol alpha

A

synthesize lagging strand and make RNA primers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Function of DNA pol delta

A

synthesize leading strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Function of DNA pol gamma

A

synthesize mitochondrial DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Function of DNA pol beta

A

base excision repair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Hyperphagia, obesity, intellectual disability, hypogonadism, hypotonia

A

Prader-Willi syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Defect in Prader-Willi syndrome

A

paternal gene on chromosome 15 is mutated/deleted; maternal gene is imprinted normally
POP - paternal, obesity/over eating, prader-willi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

inappropriate laughter, seizures, ataxia, severe intellectual disability

A

Angelman syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Defect in Angelman syndrome

A

maternal gene on chromosome 15 is mutated/deleted (paternal is imprinted)

  • think “angel’s miss their mom”
  • MAMA = angelMan, ataxia, maternal gene, mood change (very happy/laughing)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Enzyme that converts glucose to G-6-P

A

glucokinase - liver, beta cells of pancreas

hexokinase - all other tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Rate limiting enzyme in glycolysis

A

phosphofructokinase-1 (PFK-1)

converts Fructose-6-phosphate to Fructose-1,6-bisphosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What substrates promote PFK-1?

A

AMP, Fructose-2,6-bisphosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What substrates inhibit PFK-1?

A

ATP, citrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are the two enzymes that control production of F-2,6-BP (either decrease or increase its production)?

A

PFK-2 makes Fructose-2,6-BP (induced by insulin to increase glycolysis)

Fructose bisphosphatase-2 converts F-2,6-BP back to F-6-P (induced by glucagon under fasted states in order to promote gluconeogenesis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the most common glycolytic enzyme deficiency?

A

pyruvate kinase deficiency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the clinical consequence of a pyruvate kinase deficiency?

A

hemolytic anemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What enzyme is missing in muscle cells to prevent them from doing gluconeogenesis?

A

glucose-6-phosphatase

gluconeogenesis occurs in liver mostly (some in kidney and intestinal epithelium)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are the sources for gluconeogenesis?

A

odd chain fatty acids, TCA molecules, AA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the rate limiting step in gluconeogenesis?

A

fructose-1,6-bisphosphatase

converts fructose-1,6-bisphosphate to fructose-6-phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What promotes and what inhibits fructose-1,6-bisphosphatase?

A 
promotes = citrate (means high energy state)
inhibits = fructose-2,6-bisphosphate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What are the four irreversible enzymes of gluconeogenesis?

A

pyruvate carboxylase, PEP carboxykinase, fructose-1,6-bisphosphatase, glucose-6-phosphatase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

How do epinephrine and glucagon raise blood sugar?

A

stimulate protein kinase A in the liver to activate glycogen phosphorylase kinase –> release glucose from glycogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

How does insulin increase glycogen formation?

A

activated glycogen synthase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is the rate limiting step in glycogenesis?

A

Glycogen synthase - forms the alpha-1,4 glycosidic linkages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What enzyme is not found in muscles and is found in liver and acts to release glucose after glycogenolysis?

A

glucose-6-phosphatase

-reason glucose stored by muscles cell stays in that cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Rate limiting enzyme in glycogenolysis

A

glycogen phosphorylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Deficient enzyme in Von Gierke disease

A

Glucose-6-phosphatase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Deficient enzyme in Cori disease

A

debranching alpha-1,6-glucosidase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Deficient enzyme in Pompe disease

A

lysosomal alpha-1,4-glucosidase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Deficient enzyme in McArdle disease

A

skeletal muscle glycogen phosphorylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Presents with lactic acidosis, hyperlipidemia, hyperuricemia (gout)

A

Von Gierke

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Presents with cardiomegaly

A

Pompe disease (infantile type)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Presents with diaphragm weakness leading to resp. failure

A

Pompe disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Presents with increased glycogen in liver, severe fasting hypoglycemia

A

Von Gierke

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Presents with hepatosplenomegaly, hypoglycemia, hyperlipidemia (normal kidneys, lactate, uric acid)

A

Cori disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Presents with painful muscle cramps, myoglobinuria with strenuous exercise which can lead to renal failure

A

McArdle disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Severe hepatosplenomegaly, enlarged kidneys

A

Von Gierke disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Tx for Von Gierke disease

A

frequent oral glucose and cornstarch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Which glycogen storage disease is most lethal?

A

Pompe disease, infantile type

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Which glycogen storage disease can lead to seizures if untreated?

A

Von Gierke disease - due to high lactic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Possible products of pyruvate

A

oxaloacetate (gluconeogenesis), alanine (carries nitrogen), lactate (anaerobic glycolysis), acetyl-CoA (glycolysis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Two main nitrogen transporters in the blood

A

alanine, glutamine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Major regulatory enzymes in TCA cycle

A

alpha-ketoglutarate dehydrogenase, citrate synthase, isocitrate dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Rate limiting step in TCA

A

isocitrate dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What are the mitochondrial uncouplers?

A

aspirin OD, 2,4-dinitrophenol, thermogenin in brown fat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What are the cofactors required by pyruvate dehydrogenase complex (links glycolysis to TCA cycle by converting pyruvate to acetyl-CoA)?

A

TLC for Nobody

  • Thiamine pyrophosphate (Vit B1)
  • Lipoic acid
  • CoA (Vit B5, pantothenic acid)
  • FAD (Vit B2, riboflavin)
  • NAd (Vit B3, niacin)
58
Q

What toxin causes GI distress + garlic breath and inhibits pyruvate dehydrogenase?

A

arsenic

59
Q

What are the effects a deficiency in pyruvate dehydrogenase?

A

pyruvate gets shunted to lactate and alanine

  • lactate acidosis, neuro defects, increase serum alanine
  • tx = increase fat in diet, supplement with lycine and leucine to be used for energy instead of glucose
  • can be X-linked, due to arsenic, or Vit B def.
60
Q

Rate limiting enzyme in Pentose Phosphate Pathway

A

Glucose-6-phosphate dehydrogenase

converts G-6-P to Ribulose-5-P and NADPH
*important for forming NADPH

61
Q

Purpose of PPP/HMP shunt

A

form NADPH for reductive reactions

62
Q

How does G6PD deficiency presents?

A

hemolytic anemia - RBCs are unable to reduce oxidative species due to decrease in NADPH

-usually sets in after stressing factor = infection, fava beans, TB drugs, sulfonamides, nitrofurantoin

63
Q

What are the two distinct cell types seen in hemolytic anemia with G6PD def?

A

bite cells, heinz bodies (denatured Hb precipitates within cells)

64
Q

Presents with failure to thrive, jaundice, hepatomegaly, infantile cataracts, intellectual disability

A

Classic galactosemia

tx - exclude galactose, lactose from diet

65
Q

Deficiency in classic galactosemia

A

galactose-1-phosphate uridyltransferase

66
Q

Presents with galactosemia and galactosuria, infantile cataracts

A

Galactokinase deficiency

67
Q

Presents with hypoglycemia, jaundice, cirrhosis, vomiting, urine dipstick is negative for sugar

A

Fructose intolerance - severe hypoglycemia because the Fructose-1-P accumulates and there is no phosphate for glycogenolysis or gluconeogenesis

Tx - decrease intake of fructose and sucrose
*dipstick cannot pick up fructose

68
Q

What is the deficiency in fructose intolerance?

A

aldolase B

-aldolase B means this is the bad fructose dz

69
Q

What is the deficiency in essential fructosuria?

A

fructokinase

-kinase is the kind disease

70
Q

Benign dz that presents with fructose in blood and urine

A

Essential fructosuria

71
Q

What disease results from protein malnutrition?

A

Kwashiokor

72
Q

How does kwashiokor present?

A

FLAMES - fatty liver, anemia, malnutrition, edema, skin lesions (child in Africa with swollen belly)

73
Q

What disease results from total calorie malnutrition and causes muscle wasting, loss of subcutaneous fat, and edema?

A

Marasmus

74
Q

What is the rate-limiting enzyme in ketone body synthesis?

A

HMG CoA synthase

75
Q

What occurs in refeeding syndrome?

A

cells reuptake lytes –> drop in serum mag, phosphate, potassium
-can lead to arrhythmias and neuro problems

76
Q

What leads a fruity odor on the breath?

A

conversion of acetoacetate to acetate in someone who is producing ketone bodies

77
Q

What ketone body is detected on urine test?

A

acetoacetate (not Beta-hydroxybutyrate)

78
Q

What occurs in starvation and DKA to cause ketone synthesis?

A

depletion of oxaloacetate depleted for gluconeogenesis –> build up acetyl-CoA more than TCA cycle can handle

-results in glucose and FFA shunted to ketone synthesis

79
Q

What occurs in alcoholism to cause ketone synthesis?

A

excess NADH (low NAD+) shunts oxaloacetate to malate –> build up acetyl-CoA more than TCA cycle can handle

-results in glucose and FFA shunted to ketone synthesis

80
Q

What are the fuels used during fasting states?

A

glucose (glycogenolysis and gluconeogenesis), FA from fat

-glucose is used by all tissues

81
Q

What are the fuels made/used after fasting for 24 hours?

A

glucose and FA produced

  • brain uses glucose
  • muscles/other tissues use mostly FA, some glucose
82
Q

What are the fuels made/used after fasting for 48 hours?

A

glucose, FA, ketone bodies produced

  • brain uses mostly glucose, some ketones
  • muscles/other tissues use mostly FA, some ketones
83
Q

What are the fuels made/used after fasting for 5 days?

A

glucose, FA, ketone bodies produced

  • brain uses mainly ketone bodies
  • muscles/other tissues mainly use FA, some ketones

after 3 days, 60% of energy comes from ketones

84
Q

Apolipoprotein that activates LCAT

A

ApoA-I

85
Q

Apolipoprotein that mediates chylomicron secretion

A

ApoB-48

86
Q

Apolipoprotein that mediates VLDL secretion and allows particles to leave the liver

A

ApoB-100

87
Q

Apolipoprotein that mediates remnant particle uptake

A

ApoE

88
Q

Apolipoprotein that acts as a cofactor for lipoprotein lipase

A

ApoC-II

89
Q

Autosomal recessive mutation in MTP gene, presents with decrease ApoB-48 and ApoB-100, steatorrhea, night blindness and ataxia (due to decrease uptake of fat soluble vitamins)

A

Abetalipoproteinemia

90
Q

Key cells seen on a peripheral smear of a pt with abetalipoproteinemia

A

acanthocytosis of RBCs (defect in cell membrane)

91
Q

Functions to deliver dietary TGs to peripheral tissues and delivers cholesterol back to liver

A

chylomicron

92
Q

Functions to deliver hepatic TGs to peripheral tissues

A

VLDL

93
Q

Degradation product of VLDL, delivers TGs and cholesterol to liver

A

IDL

94
Q

Delivers hepatic cholesterol to peripheral tissues, take up via receptor-mediated endocytosis

A

LDL

95
Q

Deficiency in familial hypercholesterolemia

A

LDL receptor deficiency

96
Q

Mediates reverse cholesterol transport from periphery to liver, repository for ApoC and ApoE

A

HDL

97
Q

Presents with pancreatitis, hepatosplenomegaly, pruritic xanthomas, but no increased risk for arthersclerosis

high TGs, chylomicrons, cholesterol

A

Type I Hyperchylomicronemia

98
Q

Defect in Type I hyperchylomicronemia

A

lipoprotein lipase or apolipoprotein C-II deficiency

99
Q

Defect in Type IIa Familial hypercholesterolemia

A

absent or defective LDL receptors

100
Q

Presents with high LDL cholesterol, can present with an MI in a very young person (before 20), tendon xanthomas (achilles typically), increased risk or atherosclerosis

A

Familial hypercholesterolemia

101
Q

Presents with high TGs (>1000), acute pancreatitis

A

Hypertrigyceridemia - hepatic overproduction of VLDL

102
Q

Rate limiting enzyme for fatty acid synthesis

A

Acetyl-CoA carboxylase (occurs in cytoplasm)

103
Q

Rate limiting enzyme for Beta-oxidation of fatty acids

A

carnitine acetyltransferase I (occurs in mitochondria)

104
Q

Rate limiting enzyme for cholesterol synthesis

A

HMG CoA reductase

105
Q

What compounds can be made from phenylalanine?

A

tyrosine, dopa, dopamine, NE, Epi

106
Q

What is the precursor to melanin?

A

dopa

107
Q

What enzyme converts dopamine to NE and what cofactor does it need?

A

dopa beta-hydroxylase

cofactor = Vit C

108
Q

What cofactor helps convert NE to Epi?

A

SAM (also uses cortisol)

109
Q

What compounds can be made from arginine?

A

creatine, urea, nitric oxide

110
Q

What compounds can be made from glutamate?

A

GABA (requires B6), Glutathione

111
Q

What compounds can be made from glycine?

A

porphyrin (need B6) –> heme

112
Q

What compounds can be made from histadine?

A

histamine (need B6)

113
Q

What compounds can be made from tryptophan?

A

niacin (requires B6, B2) –> NAD/NADP

serotonin (requires BH4, B6) –> melatonin

114
Q

Essential Amino Acids

A

PVT TIM HaLL - phenylalanine, valine, tryptophan, threonine, isoleucine, methionine, histadine, lysine, leucine

115
Q

Acidic Amino Acids

A

Aspartate, Glutamate (negative charge at body pH)

116
Q

Basic Amino Acids

A

Arginine, Lysine, Histadine

117
Q

Amino acids that are present in histones

A

lysine, arginine

118
Q

Amino acids needed during growth

A

arginine, histadine

119
Q

Rate limiting enzyme in urea cycle

A

carbamoyl phosphate synthetase I

  • converts CO2 + NH3 (ammonia) to carbmoyl phosphate
  • found in mitochondria
120
Q

Presents with increased orotic acid in urine and blood, decreased BUN, symptoms of hyperammonemia, presents in first few days of life

A

Ornithine transcarbamylase deficiency

  • normally converts ornithine –> citrulline for elimination of ammonia
  • tx = limit protein in diet
121
Q

Tremor, slurring speech, somnolence/lethargy, vomiting, cerebral edema, blurring vision

A

hyperammonia - due to defect in urea cycle or liver disease

122
Q

Presents with dermatitis, dementia, and diarrhea but not due to deficient Vit B3

A

Hartnup disease

123
Q

Deficiency in Hartnup disease

A

deficiency in neutral amino acid transporters in the proximal tubule and on enterocytes –> decrease tryptophan for conversion to niacin –> pellegra results

124
Q

Presents with vomiting, poor feeding, urine smells sweet; can lead to CNS defects, intellectual disability, death

A

Maple syrup urine disease

125
Q

Deficiency in maple syrup urine disease

A

decreased branched-chain alpha-ketoacid dehydrogenase –> blocked degradation of branched amino acids (leucine, isoleucine, valine)

-tx = restrict branched chain amino acids

126
Q

Presents with intellectual disability, growth retardation, seizures, fair skin, eczema, and musty body odor if untreated

A

Phenylketonuria (PKU)

127
Q

Deficiency in PKU

A

decrease in phenylalanine hydroxylase or decrease in BH4 (tetrahydrobiopterin) –> can’t make tyrosine from phenylalanine

  • tx with decrease phenylalanine (aspartate, meat, dairy), increase tyrosine
  • causes build up phenylketones –> in urine
128
Q

Presents with recurrent cystine hexagonal kidney stones

A

Cystinuria

129
Q

Defect in cystinuria

A

defect in renal PCT and interstitial AA transporter that prevents reabsorption of COLA - cysteine, ornithine, lysine, arginine

tx = acetazolamide to alkalinize the urine

130
Q

Presents with increased homocysteine in the urine, intellectual disability, osteoporosis, marfanoid habitus, kyphosis, lens subluxation (downward and inward), thrombosis, atherosclerosis

A

Homocystinuria

131
Q

Defect in homocystinuria

A

Cystathionine synthase deficiency, or
decreased affinity of cystathionine synthase for pyridoxal phosphate (B6), or methionine synthase

Tx = pyridoxine (Vit B6) supplements or decrease methionine intake

132
Q

Presents with bluish-black connective tissue (skin) and sclera (onchronosis), urine turns black on prolonged exposure to air, arthalgias

A

Alkaptonuria

133
Q

Defect in alkaptonuria

A

deficiency in homogentisate oxidase –> can’t break down tyrosine –> homogentistic acid builds up in tissues

benign

134
Q

Defect in albinism

A

decreased tyrosinase activity or defected tyrosine transport –> can’t make melanin

135
Q

Cherry red spot on macula, lysosomes with onion skin, progressive neurodegeneration

A

Tay-Sachs disease

deficiency in hexosaminidase A - accumulate GM2 ganglioside

136
Q

Peripheral neuropathy, developmental delay, optic atrophy, globoid cells

A

Krabbe disease

deficiency of galactocerebrosidase - build up galactocerebrosidase

137
Q

Central and peripheral demyelination, with ataxia and dementia, vision loss

A

Metachromatic leukodystrophy

deficiency of arylsulfatase A - cerebroside sulfate

138
Q

Progressive neurodegeneration (dysphagia, dysarthria, ataxia), hepatosplenomegaly, foam cells, cherry spot on macula

A

Niemann-Pick disaese

deficiency of sphingomyelinase- build up sphingomyelin

139
Q

Hepatosplenomegaly, pancytopenia, osteoporosis, lipid-laden macrophages that resemble crumpled tissue paper

A

Gaucher disease

deficiency in glucocerebrosidase - build up glucocerebroside

140
Q

Triad of episodic peripheral neuropathy, angiokeratomas (little papules around buttock/groin), hypohidrosis

-later leads to renal failure and CV dz

A

Fabry disease (X-linked)

alpha-galactosidase A - build up ceramide trihexoside

141
Q

Developmental delay, gargoylism (course facial features and short statures), corneal clouding, hepatosplenomegaly

A

Hurler syndrome

alpha-L-iduronidase deficiency

142
Q

Mild Hurler syndrome + aggressive behavior, without corneal clouding

A

Hunter syndrome (X-linked)

iduronate sulfatase

Boards (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions