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Biochem stuff for COMLEX
Biochem stuff that might actually matter for COMLEX
59
Medical
Professional
05/28/2012

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Term
A baby presents in the neonatal unit with failure to thrive. Upon more testing you figure out that they have increased orotic acid in their urine and megaloblastic anemia. How is this disease inherited?
Definition
autosomal recessive - they have orotic aciduria
Term
How can you treat orotic aciduria?
Definition
oral uridine admin
Term
A child presents to your clinic with retarded mental development, self-mutilation, aggression, hyperuricemia, gout and choreoathetosis... what does he have?
Definition
Lesch-Nyhan Syndrome - defective purine salvage pathways (absence of HGPRT)
Term
What drugs inhibit DNA gyrase?
Definition
flouroquinolones (ciprofloxacin, levofloxacin, etc)
Term
What DNA repair mechanism is mutated in xeroderma pigmentosum?
Definition
nucleotide excision repair is messed up leading to dry skin with melanoma and other cancers (can't repair thymidine dimers)
Term
What kind of DNA repair is mutated in hereditary nonpolyposis colorectal cancer?
Definition
mismatch repair
Term
What substance is found in death cap mushrooms and what does it do?
Definition
alpha-amantin, inhibits RNA polymerase II (inhibiting mRNA => bad.)
Term
Which kinds of RNA polymerase make what?
Definition
RNA pol 1 - rRNA, RNA pol 2 - mRNA, RNA pol 3 - tRNA
Term
What do patients with lupus make antibodies to that is involved in splicing mRNA?
Definition

spliceosomal snRNPs

 

Term
What mechanism of protein production allows for disorders such as beta-thallasemia to exist? (hint - it has 4 different forms because of...)
Definition
alternative splicing
Term
What is the MOA of tetracycline antibiotics?
Definition
bind 30s subunit of ribosome, preventing attachment of tRNA
Term
What is the acronym for protein synthesis?
Definition
going APE-shit - A site holds amino-acyl RNA, P site holds growing polypeptide, E site holds empty tRNA as it exits. That's all.
Term
What syndrome involves a dynein arm deffect that leads to male and female infertility, sinus infections, and bronchiectasis?
Definition
Kartagener's Syndrome
Term
On initial exam a baby is found to already have multiple fractures and blue sclera. He seems to not hear anything and has abnormal teeth. What does he have? How is this usually inherited?
Definition
Osteogenesis Imperfecta, autosomal dominant
Term
This disorder is associated with nephritis and hearing loss due to problems with type IV collagen...
Definition
Alport's syndrome (can also have visual disturbances)
Term
Southern and Northern Blots have DNA probes to look at certain ______ and _______ samples respectively, Western blot involves...
Definition
DNA and RNA, antibody annealing to a suspected protein
Term
what is achondroplasia?
Definition
dwarfism with head and trunk normal size, cell signaling defect of fibroblast growth factor 3, aut dom
Term
What is Autosomal dom polycystic kidney disease? what's it associated with?
Definition
bilateral enlargement of kidneys due to large cysts, 90% of cases due to mutations in APKD1, berry aneurysms are associated
Term
What is familial hypercholesterolemia?
Definition
defective or absent LDL receptor, heterozygotes chol is about 300, homozygotes - 700+, results in atherosclerotic disease and tendon xanthomas
Term
What is curative for hereditary spherocytosis?
Definition
splenectomy
Term
What does Huntington's disease result from?
Definition
problem with gene on chrom 4 (trinucleotide repeats) leads to decreased levels of GABA and ACh in the brain (leads to depression, dementia, choreiform movements, etc)
Term
This disease results in cafe-au-lait spots, neural tumors, Lisch nodules and skeletal disorders while ____________ results in bilateral acoustic schwannomas and juvenile cataracts...?
Definition
neurofibromatosis type I, neurofibromatosis type II
Term
What is the most common problem with the CFTR gene in CF? Where is CFTR located?
Definition
Phe 508 deletion, chromosome 7
Term
What drug is used to treat CF and why?
Definition
N-acetylcysteine because it loosens mucous plugs by cleaving disulfide bones within mucous glycoproteins
Term
What is Duchenne's muscular dystrophy due to?
Definition
decrease in dystrophin, leads to weakness beginning in pelvic girdle, fibrofatty replacement of muscle (hypertrophied calves)
Term
What is the difference between duchenne's and becker's muscular dystrophy?
Definition
becker's is just a mutation in dystrophin, not a deletion, and is therefore less severe, presenting in adolescence/adulthood
Term
What is the acronym for Fragile X Syndrome?
Definition
Fragile X - Xtra large testis, jaw, ears
Term
the trinucleotide repeat expansion diseases are...
Definition
huntington's (CAG), myotonic dystrophy (CTG), Fragile X syndrome (CGG), and freidrich's ataxia (GAA)
Term
What are the symptoms of Edward Syndrome?
Definition
trisomy 18 --> rocker bottom feet, micrognathia (small jaw), clenched hands, prominent occiput, CHD...
Term
What substances are electron transport inhibitors (bad)?
Definition
Rotenone, CN-, antimycin A, and CO all inhibit electron transport, causing a decreased proton gradient and decreased ATP synth
Term
What drug is an ATPase inhibitor? (stops the electron transport chain...)
Definition
oligomycin
Term
What substances can uncouple the electron transport chain?
Definition
2,4-DNP, aspirin (overdose causes fever) and thermogenin in brown fat
Term
What does pyruvate carboxylase do?
Definition
changes pyruvate to oxaloacetate and requires biotin and ATP
Term
What does PEP carboxylase require? (changes oxaloacetate to PEP)
Definition
 GTP
Term
A patient comes in with tremor, slurring of speech, somnolence, vomiting and cerebral edema. You decide to limit protein in their diet and give phenylbutyrate because you think they have... which results in...
Definition
hyper ammonemia, excress NH4 depletes alpha ketoglutarate, leading to inhibition of the TCA cycle
Term
What are the symptoms of homocystinuria?
Definition
increased homocysteine in urine, mental retardation, osteoporosis, tall stature, kyphosis, lens subluxation (down and in), atherosclerosis
Term
What results in cystinuria?
Definition
defect in amino acid transport in PCT of the kidneys, leads to cysteine kidney stones, treat with acetazolamide to alkalinize the urine
Term
What results in severe CNS defects, mental retardation, death and urine that smells like maple syrup?
Definition
decreased degradation of branched chain amino acids ILV
Term
How do glucagon and insulin work on a cellular level in muscle?
Definition

glucagon activates AC to increase cAMP which actives PKA which phosphorylates glycogen phosphorylase kinase

 

insulin causes dimerization of tyr kin, which dephosphorylates glycogen phosphorylase --> less breakdown of glycogen

 

also remember that increased muscle calcium --> activates phosphorylase kinase for more glycogen breakdown to go with muslce movement

Term
What disease results in severe fasting hypoglycemia, greatly increased glycogen in the liver, increased blood lactate, and hepatomegaly?
Definition
Von Gierke's Disease - Glucose-6-phosphatase def
Term
What glycogen storage disease results in cardiomegaly and systemic findings resulting in early death?
Definition
Pomp's disease - def of lysosomal alpha-1,4-glucosidase (acid maltase)
Term
What is the difference between Von Gierke's and Cori's disease?
Definition
Cori's is a milder form of Von Gierke's that doesn't increase blood lactate, debranching enzyme is def
Term
What does McArdle's disease result in?
Definition
increased glycogen in muscle, but can't break it down leading to painful muscle cramps, myoglobinuria with strenuous exercise, skeletal muscle glycogen phosphorylase is def.
Term
What lysosomal storage disease results in peripheral neuropathy of hands and feet and cardiovascular/renal disease?
Definition
Fabry's disease - alpha galactosidase A def leading to build up of ceramide trihexoside
Term
What lysosomal storage disease results in hepatosplenomegaly, aseptic necrosis of the femur, bone crisis, and macrophages that look like crumpled paper?
Definition
Gaucher's disease - beta glucocerebrosidase def, glucocerebroside accumulates
Term
Niemann-Pick disease (AR) results in what symptoms due to a sphingomyelinase deficiency?
Definition
progressive neurodegenerative, hepatosplenomegaly, cherry red spot on macula, foam cells...
Term
What disease presents like Niemann-Pick but without the hepatosplenomegaly?
Definition
Tay-Sachs Disease, hexosaminidase A deficiency causes build up of GM ganglioside
Term
What lysosomal storage disease results in peripheral neuropathy, developmental delay, optic atrophy, and globoid cells?
Definition
Krabbe's disease - galactocerebrosidase def results in accumulation of galactocerebroside
Term
What symptoms does Metachromatic leukodystrophy result in ?
Definition
central and peripheral demyelination with ataxia, dementia due to arylsulfatase A def, cerebroside sulfate builds up
Term
What syndrome results in gargoylysm, developmental delay, airway obstruction, corneal clouding, and hepatosplenomegaly?
Definition
Hurler's syndrome
Term
what enzyme is deficient in Hurler's syndrome? what builds up?
Definition
alpha-L-iduronidase; heparin sulfate and dermatan sulfate
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