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2024 - élo - usmle rx qbank > biochem usmle rx > Flashcards

biochem usmle rx Flashcards

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USMLE® Step 1 flashcards
1
Q

deficiency of iduronate sulfate … accumulation of heparan sulfate

A

Hunter syndrome … XLR

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2
Q

DD hunter vs hurler synd

A

Hunter NO corneal clouding

Hurler YES corneal clouding

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3
Q

what happens to the potein in alpha 1 antutrypsin def

A

misfolded protein

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4
Q

centriacinar emphysema

A

smoking

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5
Q

paraacinar emphysema

A

alpha1 antitrypsin def

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6
Q

lead poisoning (enzyme)

A

aminolavilunic acid dehydratase

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7
Q

lead poisoning symptoms

A

stomach ache, vomitting, constitpation, loss of development milestones

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8
Q

type 1 glycogen storage disease

A

glucose 6 phosphatase , final step of gluconeogensis

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9
Q

MSUD deficiency of ….

A

alpha ketoacid dehydrogenase (B1)

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10
Q

def of cystathione cynthase

A

homocystinuria …. thrombosis, marfan habitus, intellect disab

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11
Q

increased Km means

A

lower affinity …. affected by competitive inhibitors

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12
Q

vascular type ehlers danlos

most common cause of death

A

type 3 collagen

rupture of berry anneurysm

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13
Q

aortic anneurysm

A

marfan synd (fibrillin 1) ch 15

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14
Q

what step in gluconeogensis requires acetyl coA

A

pyruvate carboxylase —– this yields oxaloacetate

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15
Q

which enzyme undergoes feedback inhibition by glucose 6 phosphate and which enzyme doesnt have feedback inhibition

A

hexokinase

glukokinase

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16
Q

where is glucokinase found

A

liver and B pancreatic cells

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17
Q

pyruvate kinase

A

converts phosphoenylpyruvate into pyruvate

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18
Q

mechanism of fibrates

A

activate PPAR which increases lipoprotein TG lysis via lipoprotein lipase

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19
Q

niacin mechanism

A

inhibits lipolysis via hormone sensitive lipase…. this reduces transp of free fatty acids to liver hence LOW TG

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20
Q

lactic acid production under anaerobic conditions takes place in which part of the cell

A

cytoplasm

pyruvate converted into lactic acid by lactate dehydrogenase

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21
Q

detox drugs and steroid synthesis takes place in

A

smooth endoplasmic reticulum

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22
Q

21 hydroxylase def

A

hypotension, virilization, electrolyte abn

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23
Q

retinoblastoma mechanism

A

point mutation inactivates RB tumor suppressor gene

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24
Q

Rb on chrmosome 13 can develop into

A

osteosarcoma

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25
Q

VHL

A

angiomatosis of retina, renal malignancy

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26
Q

what symptms arise in a molar pregnancy

A

hyperthyroidism due to high level of BHCG

triad of hyperemesis, hyperthyroidism and vaginal bleeding

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27
Q

PCR is used to amplify region of interest this could be usd to detect what disease

A

Cystic fibrosis

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28
Q

what is the cause of pellagra

A

tryptophan deficiency

tryptophan is used to make niacin

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29
Q

intellectual disability and hypopigmentation

A

PKU

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30
Q

coarse facial features, agg behaviour, pearly skin lesions

A

hunter )iduronate sulfatase

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31
Q

mcArdle disease

A

def of myophosphorylase

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32
Q

def of phosphoglycerate kinase

A

similar to mcARDLE BUT ALSO HAVE hemolytic anemia and CNS dysf

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33
Q

acid alpha glucosidase def

A

pompe disease

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34
Q

Very Poor Carb Metabolism

A 
von gierke ( glucose 6 phosphatase) impaired gluconeogenesis
Pompe ( acid alpha glucosidase)
Cori ( debranching ezyme) intact gluconeog... no lactate
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35
Q

Becker MD mode of transmission

A

XLR non frameshift

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36
Q

b3 def maybe seen in

A

hartnup and carcinoid

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37
Q

triad of eczema, pyogenic inf and thrombocytopenic purpura

A

wiskot aldrich … elevated igA and igE BUT LOW igM

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38
Q

CATCH 22

A

cardiac abn, abn facies, thymic aplasia, cleft palat, hypoclacemia

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39
Q

What is involved in movement of vesicles down axons

A

Microtubules… made from tubulin

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40
Q

Dyenin

Kinesin

A

Dyenin towards center minus end

Kinesis away from center positive end

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41
Q

movement from golgi to lysosome

A

Clarithin

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42
Q

Ltb4 is a

A

Neutrophil Chemotactic agent

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43
Q

CVID

A

maturation defect of B lymphocytes, poor response to immunization

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44
Q

chediak higashi is a disorder of?

A

phagocyte function … cannot empty lysosomes

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45
Q

what happens in carbomyl phosphatase synthase 1 def

A

build up of ammonia

46
Q

def of adenosine deaminase

A

SCID – inhibits purine salvage pathway

47
Q

def of ATM kinase

A

ataxia telangectasia , susceptible to XRAY damage —- later leukemia and lymphoma

48
Q

MSH2 MLH 1 DNA mismatch repair

A

lynch syndrome

49
Q

porphobilinogen demaniase

A

acute intermittent porphyria….. abd pain, red urine, neuropathy

50
Q

which blotting technique is reflective of gene expression

A

northern blot — RNA

51
Q

6 month inf hypoglycemia, seizures, hepatomegaly

A

von gierkes glucose 6 phosphatase

52
Q

galactose 1 phosphateUDT has smthn specific

A

infantile cataracts

53
Q

pt has parasthesia, confusion, ataxia, convulsions wat drug is she taking ?

A

isoniazid b6 def

54
Q

bruton agammaglobulinemia has a mutation in

A

tyrosine kinase

55
Q

thromboxane A2 role in DVT

A

causes platelet agg and vasoconstriction

56
Q

which 3 processes take place in mitochondria

A

FA oxidation, acetyl coa production and krebs cycle

57
Q

BRCA1 BRCA2 tumor suppressive or oncogene

A

tumor suppressive

58
Q

MYC gene

A

oncogene

59
Q

MEN2A

A

medullary thyroid carcinoma, pheo, parathyroid

60
Q

wasting of lysine, arginine, cysteine and ornithine

A

amino acid reabsp disorder, risk of kidney stones

61
Q

pt has a depigmented nevus, angiofibroma, epilepsy,cardiac rhabdomyoma in childhood and MRI shows multiple glial nodules
skin findings also include ash green spot and shagreen patch

A

Tuberous sclerosis, ch 9,16

62
Q

VHL most common finding

A

hemangioblastoma in retina brain and spinal cord

63
Q

alpha amanitin

A

inhibits rna pol 2 …. wch mkes mrna

64
Q

mechanism of fluoroquinolones

A

DNA gyrase (toposioneras2)

65
Q

irinotectan/topotectan

A

topoisomeras 1

66
Q

etoposide tenoposide

A

topoisomerase 2

67
Q

discoloration of teeth , injuries from minor trauma

A

osteogenesis imperfecta , lead to hearing loss

68
Q

how to treat choreiform movements in VHL

A

tetrabenazine (VMAT inhibotr) to reduce dopamine levels

69
Q

protein malnutrition is …

A

kawashiorkor

70
Q

marasmus

A

muscle wasting, anemia, growth retardation

71
Q

GLUT 4 is insulin dependent or independent

A

DEPENDENT

72
Q

malignant prolif of neuroectodermal cells is seen in

A

Ewings sarcoma

73
Q

NF 1 clinical mannifestation

A

skin changes, scoliosis, iris hamartomas (lisch nodules), risk of early bone fracture

74
Q

mutation of CD40 L

A

hyper igM syndrome —- prevent isotype class switching

75
Q

candida infection or pneumocystis jorveci , rash baby boy … decreased B and T cell count

A

SCID

76
Q

incorrect protein splicing seen in

A

B thalassemia

77
Q

truncate protein seen in

A

duchenne muscular dystrophy

78
Q

high foot arch, gait instability in a child whose uncle had similar condition

A

GAA … freidrich ataxia

79
Q

pt has svt.. after treatment complains of weight loss and feeling hot … what drug is this?

A

amiodarone, potassium blockers… prolong phase 3 ….. SE include- hyperthyroidism, pulm fibrosis, neurological effects, constipation

80
Q

what confirms immunity against hepatitis B

A

antibody against surface

81
Q

5 yr old boy has orange granules in diaper and bites his nails and lips

A

lesch nyhan ….. problem HGPRT of the purine salvage pathway …. this puts strain on denove purine synthesis and uses up all folate and b12 —– HYPERSEGMENTED neutrophils can be seen on smear

82
Q

wch antibiotic forms free radical toxic metabolites that damage cell wall

A

metronidazole rmmber its disulfram reaction with alcohol consmp

83
Q

inhibit DNA dependent RNA polymerase

A

rifampin

84
Q

inability to repair thymidine dimers leads to

A

xeroderma pigmentosa

85
Q

17 alpha hydroxylase def

A

hypokalemia …. this enzyme is used to make corticosteroids in zona fasiculata and androgens in zona reticularis

86
Q

folate deficiency describe what happens to homocysteine and methymalonic acid

A

homo is high but methyl is not

87
Q

def of lysosomal alpha 1,4 glucosidase

A

pompe

88
Q

fructose intolerance presents with hypoglycemia or hyperglycemia and why

A

hypo … aldolase b def …. fructose 1 phosphate accumulates means low levels of phosphate hence loe gluconeogenesis and glycogenolysis

89
Q

homeless man … got into a fight… bleeding gums recently … but aptt and bleeding time all normal

A

vitamin c deficiency …. problem with hydroxylation of proline residues … no proper collagen

90
Q

painless bump on penis

A

think syphilis

91
Q

anticardiolipin antibodies

A

detected in syphilis, phopholipid found in the inner mitochondrial membrane ….

92
Q

diagnose diabetes typ1

A

glucose>200, ph<7.4, bicarb, 15

93
Q

histology of the organ involved in diabetes typ1

A

lymphocytes can be seen (T cell mediated)

94
Q

histology of type 2 diabetes

A

amyloidosis

95
Q

GLUT 2 expressed on?

A

liver cells (bidirectional) , pancreatic b cells and renal tubular cells

96
Q

glitazones mechanism and SE

A

increase insulin senstivity … bind to PPAR gamma nuclear transcription regulator …..
weight gain edema and risk of fractures
SAFE IN RENAL IMPAIRMENT

97
Q

Meglitinides ( repaglinide) normally combined with metformin

A

different site from sulfanylureas but same effect –> increase post prandial insulin
SE.. hypoglycemia specially in renal imp

98
Q

GLP analog ( Exenatide)

A

inc glucose dependent insulin releae, dec glucagon, inc statiety and dec gastric emptying
SE —- rmmber pancreatitis

99
Q

DDP4 inhibitors (LIPTINS)

A

ddp4 breaks down GLP normally — they block this enzyme

SE —- urinary and resp infection

100
Q

pt given nitroprusside … can lead to what toxicity?

A

cyanide

101
Q

symp of cyanide toxicity

A

headache, cherry red lips, seizures and vomiting

102
Q

txt of cyanide tox

A

poisoning inhibits mitochondrial cytochrome oxidase which is last enzyme in ETC

103
Q

arsenic toxicity due to inhibition of

A

lipoic acid (neede in PDH complex)

104
Q

kid intellectual disability, spasticity, painful joints

A

HGPRT lesch nyhan ….. URIC acid causes pain in joints

105
Q

left shif in Hb curve means?

A

increase in affinityh for oxygen

106
Q

tumor suppressor gene p53 is located on wch chromosome

A

17

107
Q

steroid hormones from what complex

A

hormone receptor complex

108
Q

which electron carrier is used to make steroids

A

NADPH

109
Q

NADPH is a prodict of

A

HMP shunt

110
Q

NADPH can be used in

A

anabolic process

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2024 - élo - usmle rx qbank (29 decks)

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