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USMLE Step I > Biochem > Flashcards

Biochem Flashcards

(59 cards)

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1
Q

Interfere with nucleotide synthesis: Leflunomide

A

qinhibits dihydroorotate dehydrogenase

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2
Q

Interfere with nucleotide synthesis:Mycophenolate and ribavirin

A

inhibit IMP dehydrogenase

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3
Q

Interfere with nucleotide synthesis:Hydroxyurea

A

inhibits ribonucleotide reductase

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4
Q

Interfere with nucleotide synthesis:6-Mercaptopurin(and prodrug azathioprine

A

inhibit de novo purine synthesis

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5
Q

Interfere with nucleotide synthesis:5-FU

A

inhibit thymidyalte synthase (decreases dTMP)

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6
Q

Interfere with nucleotide synthesis:Methotrexate, thrimethoprim, and pyrimethamine

A

inhibit dihydrofolate reductase in humans, bacteria, and protozoa

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7
Q

abnormal splicing variant disease example

A

beta-thalassemia

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8
Q

t-arm of tRNA

A

thymine psuedouridine cytosine

necessary for ribosome binding

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9
Q

d- arm of t RNA

A

dihydrouracil

recognition by aminoacyle trNA synthase

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10
Q

variable phase of cell cycle

A

G1 and G0

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11
Q

shortest phase of cell cycle

A

mitosis

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12
Q

Li Fraumeni syndrome

A

mutations in p53 and Rb =unrestrained cell division

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13
Q

N-linked oligosaccarhide addition

A

occurs in RER

adds to ASPARAGINE

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14
Q

O-linked oligosaccarhide addition

A

occurs in GA

adds to serine and threonine

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15
Q

I cell disease

A

inherited lysosomal storage disorder
GA fails to phophorylate mannose residues on glycoproteins
proteins excreted extracellularly
coarse facial features, clouded corneas, stiff joints, high plasma levels of lysosomal proteins
fatal in childhood

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16
Q

Drugs that act on microtubules

A

Mebendazole (anti-helminthic)
Griseofulvin (anti-fungal)
Colchicine (anti gout)
Vincristine and Vinblastine (anti cancer)
Paclitaxel (anti cancer)
(Microtubules Get Constructed Very Poorly)

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17
Q

cilia structure

A

9+2 arrangement of microtubules with axonemal dynein ATPase links

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18
Q

Kartagener syndrome (primary ciliary dyskinesia)

A

immotile cilia due to dynein arm defect
male and female infertility (sperm, fallopian tube)
increased risk of ectopic pregnancy, bronchiectasis, recurrent sinusitis etc

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19
Q

Ouabain

A

inhibits Na/K ATPase by binding to K site

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20
Q

digoxin and digitoxin

A

directly inhibit Na/K ATPase = indirect inhibition of Na/Ca exchange = increased intracellular Ca = increased cardiac contractility

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21
Q

Type three collagen defects

A

vascular type of Ehlers-Danlos

defect in cross linking of collagen;in osteogenesis imperfect T1 collagen and can’t form collagen triple helix

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22
Q

Type four collagen defects

A

Alport syndrome

targeted by autoantibodies in Goodpasture

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23
Q

Copper is a necessary cofactor for…

A
  • lysyl oxidase

- deficiency in copper = kinky hair, growth retardation, and hypotonia

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24
Q

alpha antitrypsin deficiency

Study These Flashcards
A

emphysema; due to excess elastase activity

25
confirmatory test for HIV
Western blot; after ELISA
26
codominance examples
A,B, O and alpha anti-trypsin
27
variable expressivity
variable phenotype with same genotype; NF1
28
incomplete penetrance
BRCA
29
pleiotropy
one gene produces multiple unrelated phenotypic effects; PKU = mental retardation, light skin, and musty odor
30
dominant negative mutation
nonfunctional protein produced from the mutant gene prevent the the normal protein product from working
31
locus heterogeneity
different loci produce the same phenotype; albinism
32
allelic heterogeneity
different mutation at the same locus produce the same phenotype; beta-thal
33
carrier frequency (autosomal recessive)
2pq
34
x linked recessive frequency males
q
35
x linked recessive frequency females
q^2
36
chromosome 15
Prader-Willi and angelman; both can also be caused by uniparental disomy instead of imprinting
37
Prader-Willi syndrome
maternal gene is noramlly silent and the paternal gene gets deleted -hypogonadism, hypotonia, obesity, and hyperphagia
38
Angelman
paternal gene is normally silent and the maternal gene gets deleted -inappropriate laughter and seizures
39
x-linked dominant example
hypophosphatemic rickets; affected father will always transmit to daughter and never transmit to son; affected mother can transmit to daughter or son at 50% risk
40
mitochondrial inheritance
mitochondrial myopathies= ragged red fiber, lactic acidosis and CNS disease
41
polycystic kidney disease
autosomal dominant, chrom 16, PKD1 | always bilaters, massive enlargement due to multiple large cysts
42
familial adenomatous polyposis
autosomal D, chrom 5 , APC | progress to cancer unless resected
43
familial hypercholesterolemia
AD absent LDL receptor endon xanthomas
44
hereditary hemorrhagic telangiectasia
AD | telangiectasia, recurrent epistaxis, skin discolorations, GI bleeds, hematuria
45
hereditary sphereocytosis
AD elevated MCHC treatmetn splenectomy
46
Huntingtons
AD, chrom 4, CAG repeat disorder caudate atrophy decreased GABA and ACh in the brain
47
Marfan
AD, | pectus excavatum, hypermobile joints, long fingers, floppy mitral valve , subluxation of lenses
48
multiple endocrine neoplasias
AD, Men2A and B = ret gene | tumor of multiple different endocrine genes
49
Neurofibromatosis T1
AD, chrom 17, NF1 100% penetrance with variable expression cafe au lait and cutaneous neurofibromas
50
Neurofibromatosis T2
AD, chrom22, Nf2 | bilateral acoustic schwannomas, juvenile cataracts, memingiomas, and ependymomas
51
tuberous sclerosis
AD, incomplete penetrance, with variable expression neurocutaneous disorder with multi organ system involvement characterized by numerous benign hamartomas
52
von Hippel-Lindau
AD, chrom 3, deletion of VHL gene (tumor supressor gene) | numerous tumors both begin and malignant
53
cystic fibrosis
AR, defect CFTR, chrom 7 , commonly deletion of 508
54
x linked recessive disorders
Be Wise, Fools GOLD Heeds Sily H0pe brutons agam, wiskott-ald, fabrys, G6PD, ocular albinism, Lesch-Nyhan, Duchhens and Beckes, Hunters , Hemophil A and B, and ornithine transcarbamylase
55
myotonic type 1 muscular dystrophy
CTG trinucleotide repeat expansion in the DMPK gene myotonia, , muscle wasting, frontal balding, catarats, testicular atrophy, arrythmias ***think of the D in DMPK as degenerative = symptoms associated with old age
56
Trinucleotide repeat expansions
Huntingtons = CAG Fragile X= CGG Myotonic dystrophy= CTG Friedrich axtaxia = GAA
57
Robertsonian translocation
commonly involves 13,114,15,21,22
58
Cri du chat
congential micro deletion of chromosome 5 (46XX/XY 5p-) | high pithed cry, microcephaly, intellectual disability, and epidcanthal folds, cardiac abnormalities
59
Williams syndrome
congential micro deletion of long arm of jchromosome 7 (deleted region inculdes elastin gene) distinctive elfin facies, extreme friendliness with strangers, well developed verbal skills, intellectual disability, cardiovascular problems, hypercalcemia

USMLE Step I (2 decks)

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