Biochem Flashcards
Pt presents with self mutilation, mental retardation, dystonia, and gout.
What is elevated in blood stream?
What is mechanism?
FA 64
Results in excess uric acid production and de novo purine synthesis.
Defective purine salvage due to absent HGPRT:
converts Hypoxanthine into IMP
converts Guanine into GMP
X-linked recessive. Lesch-Nyhan syndrome
Pt with joint pain and hematuria has rhomboid crystals are in urine as well as hyperuricemia.
How to treat the urine crystals?
How would you treat the pt’s joint pain that they are having and what’s its mechanism?
Uric acid precipitates at acidic / low pH. Treatment is alkalinization of urine. (FA 544)
Treat gout with allopurinol which blocks xanthine oxidase to stop hypoxanthine from being converted into uric acid (FA 64)
Child is found to have cherry-red spots on macula as well as progressive neurodegeneration, hepatosplenomegaly, and foam cells.
What is the enzyme deficiency?
Classic presentation with Cherry red macula of either Tay-Sachs or Niemann-Pick (FA 624)
Niemann-Pick has hepatosplenomegaly and lipid-laden macrophages.
Enzyme deficiency is sphingomyelinase resulting in accumulation of sphingomyelin.
Cherry-red spot on macula found.
What is differentiation symptom between Niemann-Pick and Tay-Sachs disease?
Niemann-Pick has hepatosplenomegaly (sphingomyelinase deficiency) (FA 111)
Pt with developmental delay, gargoylism, and hepatosplenomegaly is found to have abnormal urine sample.
What is in urine sample / is the accumulated substance?
What could be the two diseases?
Heparan sulfate and dermatan sulfate. (FA 111)
Hurler syndrome
vs
Hunter syndrome (no corneal clouding)
Child boy with gargoylism, hepatosplenomegaly, and no corneal clouding is found to have elevated heparan sulfate and dermatain sulfate.
Enzyme deficiency? Inheritance?
Hunter syndrome: Iduronate sulfatase deficiency.
X-linked recessive. (FA 111)
Draw out diagram of lysosomal storage diseases
at top: GM2
FA 111
Classical symptoms of Gaucher disease.
Enzyme deficiency?
FA 111, 625
10 y/o pt with:
Hepatosplenomegaly
Pancytopenia (anemia, leukocytopenia)
osteoporosis
aseptic necrosis of femur ('flask' looking)
Bone section taken and histo slide is shown: Shows crumpled tissue paper macrophages
Enz: GlucocerebrosidaseFindings of Fabry
Enzyme deficiency
Peripheral neuropathy of hands/feet angiokeratomas cardiovascular/renal disease alpha - galactosidase A FA 111
10 y/o pt with angiokeratomas, peripheral neuropathy of hands and feet, and heart problems.
What enzyme deficiency?
Accumulated substrate?
alpha galactosidase A
ceramide trihexosidase
FA 111
Classic presentation of Niemann-Pick disease
enzyme deficiency
sphingomyelinase deficiency child pt with hepatosplenomegaly foam cells (lipid-laden macrophages) cherry red spot on macula FA 111, 626
Hereditary nonpolyposis colorectal cancer
enzyme deficiency
what part of cell cycle
defective mis match repair enzymes
G2
FA 67, p 113
Colorectal cancer arises de novo (not from adenomatous polyp), young age, and on right side
defective mismatch repair enzyme, G2
hereditary nonpolyposis colorectal cancer
FA 67, p113
Rifampin
inhibits prokaryotic RNA polymerase
FA 68
Amanita phalloides
death cap mushroom
alpha amanitin toxin which inhibits RNA polymerase II
hepatotoxicity
FA 68
Actinomycin D
inhibits RNA polymerase in both prokaryotes and eukaryotes
chemotherapeutic
FA 68
Pt with butterfly rash, endocarditis, fever, arthritis.
antibody testing is done. what are these antibodies specific against and what is its role?
anti smith antibodies are specific against spliceosomal snRNP’s.
these remove introns as Lariat-shaped bodies
FA 69
What is on the 3’ end of tRNA? (aminoacyl end)
what direction is the anticodon?
CCA on 3’ end, and amino acid is added here by aninoacyl-tRNA synthetase. 5’-CCA-3’
anticodon is 3’-5’ match to the 5’-3’ codon
FA 70
mRNA start codon
what does it code for
AUG
codes for methionine in eurkaryotes
codes for fMet (N formylmethionine) in prokaryotes)
mRNA stop codons
UGA, UAA, UAG U Go away U are away U are gone FA 67
mRNA start codon for prokaryotes
what is special about it
AUG codes for fMet
this is a neutrophil chemotaxic agent
FA 67
genetic difference between duchenne’s and becker’s muscular dystrophy
duchenne is frameshift insertion mutation of dystrophin gene
becker’s is non-frameshit insertion
fA 85
Child pt has calf psuedohypertrophy and has gower’s sign
Inheritance?
Frameshift mutation (not divisible by 3)
X-linked recessive
Duchenne’s Muscular Dystrophy, mutation of dystrophin gene
FA 624, 85, 66
Shigella and enterohemorrhagic E. coli (EHEC) release what toxins?
what is mechanism of these toxins?
Shiga toxin and shiga-like toxin
inactivate 60S ribosome by removing adenine from rRNA
FA 124,
symptoms of shigella? Toxin? What is the mechanism?
GI mucosal damage -> dysenterry
enhances cytokine release, causing hemolytic uremic syndrome (HUS)
Findings:
schistocytosis, renal insufficiency (thrombi), fever,
thrombocytopenia with increased bleeding time, NL PT/PTT, megakaryocytes on BM biopsy
poma 33, FA 124
Mechanism of diphtheriae toxin
inactivates elongation factor (EF-2) via ADP-ribosylation of EF-2
Ribosome moves peptidyl tRNA to P-site (translocation) during elongation
FA 124, 71
Mechansim of exotoxin A
what bacteria releases it?
ADP-ribosylation of EF-2
Ribosome moves peptidyl tRNA to P-site (translocation) during elongation
FA 124, 71
Neomycin is used for bowel surgery.
what type of bacteria is it used against?
What is the mechanism?
gram-negative rods
bctericidal; irreversible inhibition of initiation complex thru binding of 30s subunit
child presents with coarse facial features, clouded corneas, and restricted joint movement.
Suspect Hurler’s, but urine does not show ________ or ______ and blood result is high in lysosomal enzymes
enzyme defect? mechansim?
Hurler: heparan sulfate, dermatan sulfate in urine
Enz: N-acetylclugosaminyl-1-phosphotransferase
Golgi cannot phosphorylate mannose residues (decreased mannose-6-phosphate) on glycoproteins
FA 73, FA 111
High glycine content in fibroblasts suggests synthesis of what?
collagen; Gly-X-Y
wound repair
fa 76
Swollen gums, mucosal bleeding, poor wound healing, petechiae
Scurvy
vitamin C deficiency; cannot hydroxylate proline/lysine for collagen synth
FA 628, 76, 93
Blue scera, multiple fractures in child
what organelle
osteogenesis imperfect (AD) defect in collagen I synthesis glycosylation in rough endoplasmic reticulum FA 624, 76, 75
Ehlers danlos
Clinical presentation
deficiency in what
elastic skin, hypermobility of joints, increased bleeding tendency
collagen type V deficiency (III in vascular type)
FA 625, 77
elastic skin, hypermobility of joints
what heart defect?
could lead to what vascular emergency?
Mitral valve prolapse (MVP)
Ehlers-Danlos (defective collagen synthesis / cross-linking, AD or AR)
berry and aortic aneurysm
FA 77, 625
kinky hair, growth retardation, hypotonia
what gene protein defect?
mechanism?
Marfan, XLR
ATP7A - can’t absorb Cu2+, necessary for lysyl oxidase and cross-linkage of collagen
FA 77
Type IV collagen
where is it found?
What diseases?
Basement membrane, basal lamina, Lens.
Alport syndrome (XLR mutation) FA 541
Goodpasture’s (autoantibody, leading to what? FA 541)
FA 75
Hereditary nephritis, sensorineural hearing loss, cataracts
Alport syndrome (collagen IV mutation) FA 626, 75, 541
“can’t seen can’t pee, can’t hear a buzzing bee”
Adrenoleukodystrophy
XLR. Disrupted metabolism of very-long chain fatty acids -> build up in nervous system, adrenal gland, testes
long term coma/death and adrenal gland crisis
FA 489
