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Step 1 Crush 250! - Hans > Biochem > Flashcards

Biochem Flashcards

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1
Q

what enzyme is def in Fabry dz?

A

alpha-galactosidase A

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2
Q

what enzyme is def in Krabbe?

A

galactocerebrosidase

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3
Q

what are the clinical symptoms of Krabbe?

A

globoid cells, optic atrophy, developmental delay, peripheral neuropathy

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4
Q

what substrates are accumulated in Krabbe?

A

galactocerebroside, psychosine

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5
Q

what substrates are accumulated in Fabry?

A

ceramide, trihexoside

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6
Q

what enzyme is def in metachromatic leukodystrophy?

A

arylsulfatase A

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7
Q

what are the clinical symptoms of metachromatic leukodystrophy?

A

central and peripheral demyelination with ataxia, dementia

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8
Q

what substrates are accumulated in metachromatic leukodystrophy?

A

cerebroside sulfate

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9
Q

what are the second trimester quad screen values in Down?

A

low alpha fetoprotein
low estriol
high beta hCG
high inhibin A

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10
Q

quad screen values in Edward?

A

all low (low or normal inhibin A)

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11
Q

what is the unique quad screening test for Patau?

A

low PAPP-A

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12
Q

what paths are associated with inc nuchal translucency?

A

Down and Patau

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13
Q

5% of the causes for Down are

A

4%: Robertsonian translocation (2n=46)

1%: mosaicism (no maternal association, post-fertilization mitotic error)

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14
Q

what path is associated with inc sensitivity to vit D (hypercalcemia) and elfin facies?

A

Williams (microdeletion of ch#7)

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15
Q

trinucleotide repeat for friedreich ataxia?

A

GAA

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16
Q

trinucleotide repeat for huntington?

A

CAG

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17
Q

trinucleotide repeat for myotonic dystrophy?

A

CTG

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18
Q

what is the gene involved in myotonic dystrophy?

A

CTG expansion in the DMPK gene which leads to abnormal expression of myotonin protein kinase

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19
Q

what causes Prader Willi?

A

Maternal imprinting and Paternal deletion

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20
Q

what causes AngelMan?

A

Maternal deletion and Paternal imprinting

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21
Q

25% of the cause for Prader Willi is due to

A

Maternal uniparental disomy (Two imprinted maternal genes are inherited, no paternal gene received)

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22
Q

5% of the cause for AngelMan is due to

A

Paternal uniparental disomy (Two imprinted paternal genes are inherited, no maternal gene received)

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23
Q

what vit overdose lead to symptoms of pseudotumor cerebri (inc ICP, hydrocephalus, headache)?

A

vit A

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24
Q

what are symptoms of chronic vit A toxicity?

A

alopecia, dry skin (scaliness), hepatic toxicity and enlargement, arthralgias, pseudotumor cerebri

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25
what are symptoms of acute vit A toxicity?
nausea, vomiting, vertigo, blurred vision
26
what vit def lead to nyctalopia?
nyctalopia (night blindness), vit A def
27
what are symptoms of vit A def?
bitot spots on conjunctiva, frequent infection (immunesuppressed), corneal degeneration, xerosis cutis (scaly skin)
28
what vit def is associated with corneal vascularization and inflammation of lips?
vit B2 (riboflavin)
29
what vit is req for glycogen phosphorylase and decarboxylation rxn?
vit B6 (pyridoxine)
30
vit B6 (pyridoxine) can be used to treat what glycogen storage dz?
McArdle
31
what enzyme is def in Fabry?
alpha galactosidase A
32
what are the clinical symptoms of Fabry dz?
peripheral neuropathy of hands/feet, angiokeratomas, cardiovascular/renal dz
33
3 glucogenic aa?
methionine, valine, histidine
34
amino acids necessary for purine synthesis?
GAG (Glycine, Aspartate, Glutamine)
35
what drug blocks dihydroorotate dehydrogenase?
leflunomide
36
two drugs that block IMP (inosine monophosphate dehydrogenase)?
mycophenolate, ribavirin
37
clinical applications of ribavirin?
HCV, RSV(though palivizumab is preferred in children)
38
2 DOC for Lesch-Nyhan syndrome?
allopurinol, febuxostat (both xanthine oxidase inhibitor)
39
what enzyme excises RNA primer with 5' --> 3' exonuclease?
DNA pol 1
40
fluoroquinolones targets
prokaryotic enzymes topoisomerase II (DNA gyrase) and topoisomerase IV
41
what enzyme degrades RNA primer?
DNA pol I
42
3 drugs that block dihydrofolate reductase?
methotrexate, trimethoprim, pyrimethamine
43
what is the precursor of 6-mercaptopurine?
azathioprine
44
ribonucleotide reductase is inhibited by
hydroxyurea
45
2 pathologies associated with mutations in nonhomologous end joining
ataxia telangiectasia, Fanconi anemia
46
major cause of autosomal recessive SCID?
adenosine deaminase deficiency
47
explain the pathophysiology of adenosine daminase deficiency?
excess ATP and dATP imbalances nucleotide pool via feedback inhibition of ribonucleotide reductase --> prevents DNA synthesis and thus decreases lymphocyte counts
48
what 2 conditions can trigger the inc transcription in Lac operon?
1. low glucose | 2. high lactose
49
example of a frameshift mutation?
Duchenne muscular dystrophy
50
what is the name of the enzyme that fills the gap in base excision repair?
DNA polymerase beta
51
what is the mechanism of the base excision repair?
base specific glycosylase removes altered base and creates AP sites (Apurinic/apyrimidinic)
52
during what phase of cell cycle does mismatch repair takes place?
G2
53
what type of dna repair fixes bulky helix distorting lesions?
nucleotide excision repair
54
name of the enzyme that makes tRNA?
RNA pol 3
55
what is the target of alpha amanitin?
RNA pol 2
56
what blocks RNA polymerase in both prokaryotes and eukaryotes?
Actinomycin D
57
which enzyme opens DNA at promoter site?
RNA pol 2
58
what is the most common form of osteogenesis imperfecta?
autosomal dominant with dec production of normal type 1 collagen
59
in OI, what causes the hearing loss?
abnormal ossicles
60
describe the tooth abnormalities in OI
opalescent teeth that wear easily due to lack of dentin (dentinogenesis imperfecta)
61
OI can be confused with
child abuse
62
during the cross linking process of collagen what plays an important role?
reinforcement of many staggered tropocollagen molecules by covalent lysine-hydroxylysine cross linkage (by copper containing lysyl oxidase) to make collagen fibrils
63
what are the 2 paths associated with problems in cross linking?
Ehlers Danlos, Menkes
64
In Menkes, what protein causes the problem?
ATP7A protein leads to dec activity of lysyl oxidase which utilizes copper
65
what nutrition can lead to delayed wound healing, hypogonadism, dysgeusia
zinc
66
why is zinc important?
important in the formation of zinc fingers which are transcription factor motif
67
what serves as scaffolding with fibrillin?
tropoelastin
68
name 3 major amino acids that make up elastin?
nonhydroxylated proline, glycine, and lysine
69
what gives elastin its elastic properties?
extracellular cross linking
70
what inhibits elastase?
alpha 1 antitrypsin
71
causes for wrinkles?
due to dec collagen and elastin production
72
urinary cyanide-nitroprusside test came out positive, what is the diagnosis?
cystinuria
73
what is the defect in cystinuria?
hereditary defect of renal PCT
74
name of the rate determining enzyme in glycolysis?
phosphofrucktokinase 1 (PFK-1)
75
rate determining enzyme of gluconeogenesis?
fructose 1,6 bisphosphatase
76
rate determining enzyme of TCA cycle?
isocitrate dehydrogenase
77
what vitamin def leads to broad collar rash?
vit b3, niacin
78
path associated with precocious puberty, multiple endocrine abnormalities, and unilateral cafe au liat spot?
McCune Albright syndrome
79
path associated with "polyostotic fibrous dysplasia?"
McCune Albright syndrome
80
what is another path associated with "cafe au liat spots?"
neurofibromatosis type I (von Recklinghausen dz)
81
what path can mimic pellagra like symptoms? and why?
Hartnup
82
disulfiram blocks what enzyme?
acetaldehyde dehydrogenase
83
what drug blocks alcohol dehydrogenase?
fomepizole
84
what are the clinical applications for fomepizole?
methanol and ethylene glycol antidote
85
apolipoprotein that functions as lipoprotein lipase cofactor?
C-II
86
apolipoprotein that functions LCAT (lecithin-cholesterol acyltransferase) activator?
A-1
87
what apolipoprotein mediates chylomicron secretion?
B-48

Step 1 Crush 250! - Hans (41 decks)

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