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Biochemistry-Molecular/Genetics Flashcards

1
Q

What is rate limiting step of de novo purine nucleotide synthesis?

A

glutamine PRPP (5-phosphoribosyl-1-pyrophosphate) amidotransferase; inhibited by downstream products: IMP, GMP, AMP; cofactors: THF, glutamine, glycine, aspartate

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2
Q

Lesch-Nyhan Syndrome

A

HGPRT (converts hypoxanthine to IMP and guanine to GMP); tx w/ allopurinol (inhibits xanthine oxidase); X linked recessive

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3
Q

Severe combined T and B immunodeficiency

A

Adenosine deaminase deficiency; causes excess ATP/dATP and inhibits ribonucleotide reductase creating imbalance in nucleotide pool; autosomal recessive

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4
Q

Hereditary orotic aciduria

A

orotate phosphoribosyl transferase and/or OMP decarboxylase deficiency

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5
Q

Amino acids required for purine synthesis

A

glycine, aspartate, glutamate (used by glutamine PRPP amidotransferase)

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6
Q

converts ribonucleotides to deoxyribonucleotides

A

ribonucleotide reductase (inhibited by dATP, feedback)

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7
Q

inhibits dihydroorotate dehydrogenase

A

leflunomide

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8
Q

inhibit IMP dehydrogenase

A

mycophenolate, ribavirin

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9
Q

inhibits ribonucleotide reductase

A

hydroxyurea

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10
Q

inhibits de novo purine synthesis

A

6-MP and azathioprine (6MP prodrug)

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11
Q

thymidylate synthase

A

5-FU

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12
Q

inhibits dihydrofolate reductase in humans, bacteria, or protozoa

A

methotrexate (humans), trimethoprim (bacteria), pyrimethamine (protozoa)

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13
Q

DNA polymerase III

A

5’-3’ DNA synthesis; 3’-5’ exonuclease activity

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14
Q

DNA polymerase I

A

5’-3’ exonuclease activity, excises RNA primer (put down by primase)

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15
Q

endonuclease

A

nucleotide excision repair, base excision repair (glycosylase-AP site)

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16
Q

defective nucleotide excision repair

A

xeroderma pigmentosum–UV induced pryimidine dimers

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17
Q

defective mismatch repair

A

HNPCC

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18
Q

defective NHEJ

A

ataxia telengectasia

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19
Q

drugs that block DNA replication often have what modification?

A

3’-OH group to prevent addition of next nucleotide (DNA/RNA is synthesized 5’-3’

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20
Q

mRNA start codon

A

AUG (rarely GUG)

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21
Q

mRNA stop codons

A

UGA, UAA, UAG

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22
Q

inhibits RNA polymerase II

A

alpha-amantin (from death cap mushrooms); causes severe hepatotoxicity

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23
Q

cytoplasmic P bodies

A

mRNA quality control, contains exonucleases, decapping enzymes, microRNAs

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24
Q

anti smith antibodies

A

antibodies to spliceosomal snRNPs (highly specific for SLE)

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25
anti U1 RNP
antibody to snRNP70--highly associated with mixed connective tissue disease
26
which end of tRNA carries amino acid? what sequence?
ALL tRNAs have a CCA on 3' end that carries AAs
27
T-ARM of tRNA
contains thymidine/pseudourine/cytosine sequence necessary for tRNA ribosomal binding
28
D-ARM of tRNA
contains dihydrouracil residues necessary for tRNA recognition by the correct aminoacle-tRNA synthetase
29
Anticodon loop of tRNA
binds mRNA and is opposite the ACC/amino acid end
30
charging tRNA
aminoacyl-tRNA synthetase, requires ATP, 1 per amino acid matchmaker; requires D-arm of ATP for correct binding
31
tRNA translocation/activation
requires GTP/ATP respectively
32
course facial features, clouded corneas, restricted joint movement, high plasma levels of lysosomal enzymes
I-cell disease: inherited lysosomal storage disorder, defect in phosphotransferase, failure of golgi to phosphorylate mannose residues-->proteins delivered extracellularly instead of to lysosomes
33
What specifics does the Golgi modify?
modifies N-oligosaccharides on asparagine, adds O-oligosaccharides on serine/threonine, adds mannose-6-phosphate to proteins for lysosomal trafficking
34
traffics protein from ribosome to RER
signal recognition particle (SRP); ribonucleoprotein; when deficient-->proteins accumulate in cytosol
35
retrograde trafficking
COP1
36
anterograde trafficking
COP2
37
trans-golgi trafficking
clathrin
38
vimentin
connective tissue
39
desmin
muscle
40
cytokeratin
epithelial cells
41
GFAP
neuroglial cells
42
neurofilaments
neurons
43
Type 1 Collagen; disease?
Bone, skin, tendon, dentin, fascia, cornea, late wound repair; osteogenesis imperfecta type I
44
Type 2 collagen
cartilage (including hyaline); vitreous body, nucleus puplosus
45
Type 3 collagen, disease?
reticulin--skin, blood vessels, uterus, fetal tissue, granulation tissue--Ehler Danlos vascular type
46
Type 4 collagen; diseases?
basement membrane, basal lamina, lens; alport syndrome, goodpasture syndrome
47
which step of collagen synthesis is defective in osteogenesis imperfect?
Glycosylation step; formation of procollagen via hydrogen and disulfide bonds to form triple helix of procollagen
48
which step of collagen synthesis is defective in Ehler Danlos?
Cross linking step; Cu2+ containing lysyl oxidase; final step to make collagen fibrils
49
multiple fractures with minimal trauma occurring during birth process
Osteogenesis imperfecta--autosomal dominant with decreased production of otherwise normal type I collagen; blue sclerae, hearing loss, dental imperfections
50
brittle/kinky hair, growth retardation, low muscle tone as child
Menkes disease--impaired copper absorption and transport--decreased activity of lysyl oxidase; problems crosslinking
51
hyperphagia, obesity, intellectual disability, hypogonadism, hypotonia
Prader Willi syndrome; maternal imprinting (paternal gene is deleted); chromosome 15
52
inappropriate laughter, seizures, ataxia, severe intellectual disability
Angelman Syndrome; paternal imprinting (materal gene deleted); chromosome 15
53
Example of x-linked dominant disorder
hypophosphatemic rickets (increased phosphate wasting at PCT)
54
myopathy, lactic acidosis and CNS disease
mitochondrial myopathy; failure in oxidative phosphorylation; muscle biopsy shows ragged red fibers; mitochondrial inheritance
55
ADPKD
autsomal dominant; PKD1 (chromosome 16); PKD2 (chromosome 4)
56
FAP
autosomal dominant; APC (chromosome 5; polyp has 5 letters)
57
telangectasia, recurrent nosebleeds, skin discoloration, AVMs, gi bleeding, hematuria
Hereditary hemorrhagic telangectasia, autosomal dominant, aka Osler Weber Rendu syndrome
58
Huntington disease
AD; chromosome 4; CAG repeats
59
cystic medial necrosis of aorta; floppy mitral valve, lens subluxation typically upward and temporally
Marfan syndrome--fibrillin 1 defect (sheath for elastin)
60
MEN syndromes inheritance pattern
autosomal dominant
61
cafe au lait spots and cutaneous neurofibromas
NF1, AD, chromosome 17
62
bilateral acoustic schwannomas, juvenile cataacts, meningiomas, ependymomas
NF2, AD, chromosome 22
63
numerous benign hamartomas
tuberous sclerosis--AD, incomplete penetrance, variable expression
64
retinal, medullary, cerebellar angiomas, bilateral renal cell carcinoma
von hippel lindau disease; AD, chromosome 3
65
cystic fibrosis
CFTR gene on chromosome 7; AR
66
Some autosomal recessive diseases:
albinism, ARPKD, CF, glycogen storage diseases, hemochromatosis and Wilsons, Kartagener, mucopolysaccharidoses (except Hunter syndrome X linked R); PKU, sickle cell, sphingolipidoses (except Fabry XLR w/ incomplete penetrance), thalassemias
67
X-linked Recessive disorders
Be Wise Fools GOLD Heeds Silly HOpe: bruton, wiskott-aldrich, fabry, G6PD, ocular albinism, Lesch Nyhan, Duchenne (and becker), hemophilia A/B, Hunter syndrome, OTC deficiency
68
myotonia, muscle wasting, frontal balding, cataracts, testicular atrophy, arrhythmia
Myotonic type 1 dystrophy--CTG repeats in CMPK gene
69
post-pubertal macroorchidism, long face with large jaw, large everted ears, autism, mitral valve prolapse
Fragile X syndrome--X-linked CGG repeats in FMR1 gene
70
What are the trinucleotide repeats in common repeat disorders:
X-Girlfriends First Aid Helped Ace My Test: Fragile X--CGG; Friedrich's ataxia--GAA; Huntington--CAG; Myotonic dystrophy--CTG
71
Imaging and lab findings in Down Syndrome
First trimester US: increased nuchal translucency, hypoplastic nasal bone; serum PAPP-A is decreased, free bHCG is elevated; Quad screen: decreased AFP and estriol; increased bHCG and inhibinA
72
Lab findings in Edwards syndrome
everything is down
73
US and Lab findings in Patau syndrome
everything is down, but increased nuchal translucency
74
microcephaly, moderate to severe intellectual disability, crying/mewing, epicanthal folds, cardiac abnormalities (VSD)
Cri du chat--microdeletion of short arm of chromosome 5 46XX/XY, 5p-)
75
elfin facies, intellectual disability, hypercalcemia, conversant, extremely friendly, cardiovascular problems
Williams Syndrome--microdeletion of long arm of chromosome 7
76
22qll deletion
Cleft palate, abnormal facies, thymic aplasia, cardiac defects, hypocalcemia (parathyroid aplasia)--defects in 3/4th branchial pouch formation--DiGeorge, velocardiofacial syndrome

(First Aid) + Pharm + (Secrets) (36 decks)

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