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Biochem
Biochem for Step 1 of USMLE
76
Medical
Graduate
06/05/2010

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Cards

Term
Direction of DNA replicaion
Definition
5' -> 3'
Term
DNA pol III
Definition
Prok only
elongates leading and lagging strands by adding deoxynucleotides to the 3' end (5' -> 3' synthesis)
Has 3'-> 5' exonuclease/proofreading capability
Term
DNA Pol I
Definition
prok only
degrades RNA primers and fills in the gaps w/ DNA 5' -> 3' exonuclease
Term
problem in xeroderma pigmentosum
Definition
nucleotide excision repair
Term
Direction of mRNA reading
Definition
5' -> 3'
Term
Where Transcription factors bind
Definition
Enhancer site
Term
where suppressors bind
Definition
silencer site
Term
where silencers and enhancers are located in relation to the gene
Definition
anywhere: close to, far way or w/i a gene
Term
Types of RNA polymerase in euks
Definition
RNA pol I- makes rRNA
RNA pol II- makes mRNA
RNA pol III- makes tRNA
Term
where RNApol binds tin initiate transcription
Definition
promoter- TATA or CAAT boxes
Term
snRNPs
Definition
make up the spliceosome and carry out splicing of introns
Term
MOA of tetracyclines
Definition
bind the 30S subunit and inhibit the attachement of aminoacyl-tRNA
Term
Catalyzes the peptide bond formation and moves the growing chain from the tRNA in the P site to the A site
Definition
peptidyltransferase
Term
binds to the 50S subunit and prevents translocation
Definition
Clindamycin and Macrolides
Term
inhibits 50S peptidyltransferase
Definition
Chloramphenicol
Term
inhibits the formation of the initiation complex
Definition
AGs
Term
Inhibit G1 -> S progression
Definition
Rb and p53
Term
Name of RER in neurons
Definition
Nissel substance
Term
Targets proteins to lysosome
Definition
mannose-6-phosphate residue
Term
AA that is sulfated
Definition
Tyronsine
Term
aa to which O-oligosaccharides are attahced
Definition
serine and threonine
Term
aa to which N-oligosaccharides are attahced
Definition
asparagine
Term
coarse facial features
restricted joint movements
clouded corneas
high plasma lysosomal enzyme levels
Definition
I cell dz
failure to add mannose-6-phospate to lysosomal enzymes so they are secreted from cells rather than targeted to lysosomes
Term
retrograde motor protein
Definition
dynein
Term
anterograde motor protein
Definition
kinesin
Term
drugs that act on MTs
Definition
1. mebendazole/thiabendazole (anti-helminth)
2. griseofulvin (anti-fungal)
3. vincristine/vinblastine (anti-cancer)
4. paclitaxel (anti-breast cancer)
5. colchicine (anti-gout)
Term
cytoskeletal elements involved in muscle contraction, microvilli, tight jxns
Definition
actin and mysin
Term
drug that inhibits Na/K ATPase by binding the the K+ binding site
Definition
Ouabain
Term
Flat facies, prominent epicanthal folds, simian crease
Definition
Down Syndrome (21)
Term
microagnathia and clenched hands
Definition
Edwards Syndrome (18)
Term
Cleft lip/palate, holoprosencephaly, polydactyly
Definition
Patau syndrome (13)
Term
Thiamine
Definition
B1
In thiamine pyrophosphate (TPP)
Cofactor for: pyruvate dehydrogenase, AKG dehydrog, transketolase (HMP shunt), branched chain AA dehydrog.
Term
riboflavin
Definition
B2
cofactor in FADH2 and FMN for oxidation and reduction rxns
dificieny results in chelosis and corneal vascularization
Term
Niacin
Definition
B3
Part of NAD and NADP (redox rxns) derived from tryptophan and requires B6 for synthesis
deficiency causes glossitis, can lead to pellagra (which can be caused by Hartnup's dz, malignant carcinoid syndrome and INH)
Term
Pantothenate
Definition
B5
component of CoA for acyl transfers
deficiency causes dermititis, enteritis, allopecia and adrenal insufficiency
Term
Pyridoxine
Definition
B6
Part of pyrodoxal phosphate which is needed for transamination, decarboxylation, glycogen phosphorylase, and heme synthesis.
Also required for niacin (B3) production from tryptophan
deficiency causes convulsions, hyperirritability, peripheral neuroathy
Term
drugs causing B6 deficiency
Definition
OCPs and INH
Will B3 deficiency
Term
Biotin
Definition
Needed for carboxylation rxns
Pyruvat carboxylase allows progression of TCA
Acetyl-CoA carboxylation allows for oxidation of FA
Propinoyl-CoA allows for the connection of FA oxydation to the TCA cycle
Term
Vitamin C
Definition
needed for:
1. needed for hydroxylation in collagen synthesis
2. needed for B-hydroxylase of dopamine to NE
3. keeps Fe in +2 valence state
Term
Vitamine needed to protect erythrocytes from free radical damage
Definition
Vit E
Term
Excess Ile, Leu and Val in blood
Definition
Maple Syrup urine dz
inability to degrade branched amino acids b/c of no alpha-ketoacid dehydrogenase
Term
Sever combined Immune difficiency
Definition
Adenine deaminase difficiency causes a defect in DNA synthesis which lowers lymphocyte count
Term
Self-mutilation
Definition
Lesch-Nyhan deficiency
Term
diffeciency in Glucose-6-phosphatase
Definition

Von Girke's Dz/Type I glycogen storage dz

severe fasting hypoglycemia

↑↑ glycogen in liver

↑ blood lactate levels 

Hepatomegally

Term

Deficiency in lysosomal α-1,4-glucosidase

(acid maltase)

Definition

Pompe's Dz/Type II glycogen storage dz

cardiomegaly and systemic findings leading to an early death

Term

Deficiency in debranching enzyme/ α-1,4-glucosidase

 

Definition

Cori's Dz/Type III glycogen storage dz

milder for of Von Girke's w/ normal blood lactate levels

Gluconeogenesis is in tact

Term
Deficiency in skeletal muscle glycogen phosphorylase
Definition

McArdle's Dz/Type V glycogen storage dz

 

 ↑ glycogen in muscle, but cannot break it down leading to painful muscle cramps and myoglobinuria w/ strenuous exercise

 

Impaired energy production

Term
Cherry Red spot on Macula
Definition
Tay Sach's or Niemann-Pick
Term
Accumulation of ceramide trihexoside
Definition
Fabry's dz (lysosomal storage dz)
Term
accumulation of glucocerebroside
Definition

Gaucher's Dz (MC Lysosomal storage dz)

Sphingolipidosis

Term
Only lysosomal storage dzs w/  non-Auto-recessive MOI
Definition

Fabry's Dz (sphingolipidosis) - X-linked recessive

 

Hunter's Dz (muccopolysaccharidosis) - X-linked recessive

Term
accumulation of sphingomyelin
Definition

Niemann-Pick Dz

Lysosomal Storage dz- Sphingolipidosis

Term

Accumulation of GM2 Ganglioside

 

Definition

Tay Sach's Dz

Lysosomal Storage Dz- sphingolipidosis

Term
accumulation of galactocerebroside
Definition

Krabbe's Dz

Lysosomal storage dz- sphingolipidosis

Term
Accumulation of Cerebroside sulfate
Definition

Metachromatic leukodystrophy

Lysosomal storage dz- phospholipidosis

Term
Accumulation of heparan sulfate and dermatan sulfate
Definition

Hurler's Syndrome or Hunter's syndrome

lysosomal storage dz- mucopolysaccharidosis

 

Diff b/w Huler's and Hunters:

Hunter's is more mild and does not cause corneal clouding, but it does have more aggressive behavior

Also, Hunter's syndrome is X-linked recessive

Term
Apolipoprotein A-1
Definition
activates LCAT
Term
Apolipoprotein B-100
Definition

Binds to LDL receptor

 

Mediates VLDL secretion

Term
Apolipoprotein C-II
Definition
Cofactor for lipoprotein lipase
Term
Apolipoprotein B-48
Definition
Mediates Chylomicron secretion
Term
Apolipoproteins E-3 and E-4
Definition
mediates chylomicron remnant uptake
Term
Apolipoproteins on Chylomicrons
Definition

B-48

A-IV

C-II

E

Term
Apolipoproteins on VLDL
Definition

B-100

C-II

E

Term
Apolipoproteins on IDL
Definition

B-100

E

Term
Apolipoproteins on LDL
Definition
B-100
Term
Lipoprotein lipase deficiency
Definition

Type I Familial Dyslipidemia -hyperchylomicronemia

Elevated blood TG and Cholesterol

Term
Altered Apolipoprotein C-II
Definition

Type I familial dyslipidemia- Hyperchylomicronemia

elevated blood TGs and Cholesterol

Term
Absent or decreased LDL receptors
Definition

Type IIa familial dyslipidemia- familial hypercholesterolemia

 

Elevated Blood cholesterol levels

Term
Hepatic overproduction of VLDL
Definition

Type IV familial dyslipidemia- hypertriglyceridemia

 

Elevated blood levels of TG

Term

hereditary inability to synthesize lipoproteins due to deficiencies in ApoB-100 or ApoB-48

 

Definition

Abeta-lipoproteinemia

findings: FTT, steatorrhea, acanthocytosis, ataxia, night blindness

Term
FTT, steatorrhea, acanthocytosis, ataxia, night blindness
Definition
abeta-lipoproteinemia
Term
Lack of ABC1
Definition

Tangier's Dz

 

inability for cells to excrete cholesterol

 

Low HDL and cholesterol collection in cells

Term
Orange Tonsils
Definition
Tangier's Dz
Term
Diff b/w Orotic Aciduria and Ornithine Transcarbamoylase Deficiency
Definition

Orotic Adicuria: ↑ Orotic acid in urine (and megaloblastic anemia that doesn't improve w/ b12 or folic acid + FTT) and NO hyperammonemia

 

OTC deficiency: ↑ Orotic acid in urine + hyperammonemia

Term
Loss of amino acids in urine
Definition
Hartnup Dz
Term
Pellagra
Definition
low B3/Niacin.
Caused by Hartnup dz b/c Niacin is derived from tryptophan
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