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USMLE Organ Systems > BioChem > Flashcards

BioChem Flashcards

0
Q

Microtubules are used for what main function (and 5 subcategories)?

A

Movement

[cilia, flagella, mitotic spindle, axonal trafficking, centrioles]

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1
Q

Actin/Myosin are used for what 4 things?

A

muscle contraction, microvilli, cytokinesis, adherens junction

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2
Q

Intermediate filaments are used for what main function?

A

Structure

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4
Q

Intermediate filaments have what 5 types? Each is located where?

A
  • Vimentin - connective tissue
  • DesMin - Muscle
  • Cytokeratin - epithelial cells
  • Gfap- NeuroGlia
  • Neurofilaments - Neurons
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5
Q

Type 1 collagen: What 7 functions?

A

bone, skin, tendon,

dentin, fascia, cornea, late wound repair

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6
Q

Type 2 collagen: what 3 uses?

A

cartilage,

vitreous body, nucleus pulposus

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7
Q

Type 3 collagen: what 5 uses?

A

Reticulin

[BLOOD VESSELS, skin, uterus, fetal tissue, granulation tissue]

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8
Q

Type 4 collagen: what 3 uses?

A

basement membrane,

basal lamina, lens

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9
Q

ADPKD: chromosome & char?

A

PKD1 (85%)=16, PKD2=4.

  • Always bilateral enlargement due to large cysts
  • Think of “cysts in kidney, liver, and brain (aneurysms) plus mitral prolapse”
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10
Q

Fam Aden Polyposis: chromosome & char?

A
  • 5
  • Colon covered in polyps post-puberty. -> Cancer.
  • Also other GI, thyroid, CNS tumors
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11
Q

Fam Hypercholesterolemia: char?

A
  • Defective or absent LDL receptor

- Xanthomas/athero, esp achilles

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12
Q

Hereditary hemorrhagic telangiectasia: char?

A
  • think of complications of vessels. A.k.a. Osler-Weber-Rendu
  • Telangiectasia
  • RECURRENT epistaxis
  • Lip splotches
  • skin discoloration, arteriovenous malformations, GI bleed, hematuria
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13
Q

Hereditary spherocytosis: char?

A

1) ankyrin 2)spectrin. Up MCHC (heme conc.)

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14
Q

Huntington: chromosome & char?

A
  • Hunting 4 food
  • Depressed, crazy, & dancing (chorea) in a CAGe w/ caudate atrophy & down GABA, ACh
  • Hypermethylation of histones -> Gene silencing
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15
Q

Marfan: chromosome & char?

A
  • Fibrillin-1

- Cystic medial necrosis of aorta->dissection, floppy mitral. Sublux of lens up and temporally. Other classic things.

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16
Q

Tuberous sclerosis: char? (yes all are important to memorize)

A
  • benign hamartomas (neurocutaneous & ANY organ system)
  • Renal angiomyolipomas
  • Ash leaf spots
  • rhabdomyoma
  • adenoma sebaceum in nasolabial folds (acne-like papules)
  • seizures
  • incomplete penetrance AND variable expression
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17
Q

von Hippel-Lindau

A
  • 3p (3 words) VHL gene (tumor suppressor deletion) auto dominant
  • Abnormal vessel growth -> Tumors everywhere benign/malignant!
  • Hemangioblastomas in CNS
  • Bilateral renal cell carcinoma (“3p is for peeing”)
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18
Q

Achondroplasia: gene and char?

A
  • FGFR3
  • Normal trunk, tiny limbs, bulging forehead.
  • Due to advanced paternal age! 70% are spontaneous mutations.
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19
Q

i cell dz: defect? clinical presentation?

A
  • Golgi phosphotransferase (phosphorylates mannose residues to send to lysosome)
  • Coarse facial features, clouded cornease, restricted joint movement, high plasma lysosomal enzymes
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20
Q

Drugs that act on microtubules?

A

“microtubules get constructed very poorly”

  • mebendazole (helminth)
  • griseofulvin (fungal)
  • colchicine (gout)
  • vincristine/vinblastine (cancer)
  • paclitaxel (cancer- uniquely, prevents DEpolymerization)
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21
Q

Collagen synthesis steps?

A
  1. Make Gly - X - Y (often X and Y are proline, lysine)
  2. Hydroxylate (vit C)
  3. Glycosylate hydroxylysine then PROCOLLAGEN H and disulfide bonds form (triple helix, prob=osteogenesis imperfecta)
  4. Exocytosis
  5. Cleave disulfide terminal regions ->insoluble tropocollagen
  6. Covalent-link tropocollagens (staggered) at lysine-hydroxylysine by Cu-containing (Menke’s Dz=Cu deficiency) lysyl oxidase ->collagen. (prob crosslinking= Ehlers Danlos)

[recall Zn is needed to break down collagen (wound healing]

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22
Q

Osteogenesis Imperfecta clinical presentation?

A

“Osteogenesis Imperfecta degrades you FAST”

  • Fractures
  • Auditory ossicles (hearing loss)
  • Sclera (BLUE!!)
  • Teeth (lack dentin)
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23
Q

Which connective tissue component is NOT hydroxylated at proline?

A

Elastin

[recall alpha 1 antitrypsin inhibits elastase]

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24
Q

What a.a.’s are needed to make purines?

A

“Need these to GED (get) purines” (using their 1-letter codes)
G (glycine)
E (glutamate)
D (aspartic acid)

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25
What drug is used for choreocarcinoma?
methotrexate
26
What 3 drugs affect DNA topoisomerase?
fluoroquinolones, irinotecan, topotecan
27
What amino acids aren't "redundant" in their code?
methionine (AUG), tryptophan (UGG)
28
DNA Pol 3 (prokaryotic) has what kind of exonuclease? Howa about DNA Pol 1?
- 3 to 5 (to proofread) | - 5 to 3 (to excise RNA primer)
29
Nuceotide Excision Repair is for?
- "NER repair= bulky XER disease" - ENDONUCLEASE activity [nucleotide excision repair is for bulky (pyrimidine dimers due to UV) repair. A defect gives xeroderma pigmentosum. (premature skin agin, multiple melanomas, sunburn, dry cracking skin)]
30
Base excision repair is for?
- "Bring cartoons to BASE when they've been spontaneously DE-ANIMATED" - GLYCOSYLASE activity, followed by the normal NER steps.
31
Mismatch repair is for?
- Newly synthesized DNA repair | - "Giving MISMATCHED RECTUMS (HNPCC) to the wrong patient would be disastrous!"
32
Nonhomologous end joining is mutated in what diseases?
ataxia telangiectasia, BRCA, FANCD2, CHK2
33
What would be the Spontaneous Deamination of the following nucleotides? C, adenine, G
C-> U Adenine ->hypoxanthine G -> Xanthine
34
What is the DNA replication termination signal?
AATAAA | "ata' boy, you're all done!"
35
An intron begins with what? Ends with what?
- GU "GT started" (DNA strand will be a GT not GU) | - AG "AG done" (All done, like a child is saying it)
36
Anti-U1 RNP antibodies indicate what dz?
Mixed connective tissue disease
37
Anti-Smith antibodies (lupus) attack what?
snRNP's (normally help splice pre-mRNA)
38
Polyadenylation signal?
AAUAAA (notice similarity to DNA replication termination signal: AATAAA)
39
Rb (tumor suppressor) is on what chromosome?
13 (think cancer and 13! scary!)
40
ouabain: mechanism?
binds K site of Na/K pump
41
digoxin: mechanism?
inhibits ATPase of Na/K pump
42
Auto Recessive diseases? (minus the ones that are obvious)
- albinism - glycogen storage diseases - hemochromatosis - Kartagener - All lysosomal storage dz except Fabry and Hunter - PKU - thalassemias - Wilson dz
43
X-linked recessive disorders?
"Friendly BOG SCOWLD: SHH !!" - Fabry - Bruton - Ocular albinism - G6PD - Sideroblastic anemia due to mutation in rate-limiting Delta-ALA synthase - Chronic Granulomatous dz - Ornithine transcarbamylase deficiency - Wiskott-Aldrich - Lesch-Nyhan - Duchenne (and Becker) - SCID - Hemophilia A & B - Hunter syndrome
44
fomepizole function?
inhibits alcohol dehydrogenase (1st step). Antidote for methanol or ethylene glycol poisoning, NOT isopropyl)
45
Disulfiram function?
inhibit acetaldehyde dehydrogenase
46
Which metabolisms occur in mitochondria?
FA oxidation, acetyl-CoA production, TCA cycle, ox phos
47
Which metabolisms occur in cytoplasm?
glycolysis, FA synth, HMP shunt, protein synth (RER), steroid synth (SER) & cholesterol synth
48
Which metabolisms occur in both places?
HUGs take two. | Heme synth, urea cycle, gluconeogenesis
49
Arsenic function?
glycolysis produces zero net ATP
50
What is carried by CoA & lipoamide?
acyl groups R-C=O
51
What is carried by biotin?
CO2
52
What is carried by THF?
1-carbon units
53
What is carried by SAM?
CH3 groups
54
What is carried by TPP?
aldehydes
55
Arginine can be made into?
creatine urea nitric oxide (req BH4)
56
Glutamate can be made into?
GABA (req B6) | Glutathione
57
Glycine can be made into?
porphyrin (req B6) -> Heme
58
Histidine can be made into?
histamine (req B6)
59
Tryptophan can be made into?
Niacin (req B6) ->NAD+ | Serotonin (req B6 & BH4) -> melatonin
60
Phe requires what cofactor to make tyrosine?
BH4
61
Tyrosine requires what cofactor to make dopa?
B6 | [tyrosine can also make thyroxine or homogentisic acid]
62
Dopa requires what cofactor to make dopamine?
B6 | [Dopa can also make melanin]
63
Dopamine requires what cofactor to make NE?
Vit C
64
NE requires what cofactor to make Epi?
SAM | [Cortisol stimulates this conversion!]
65
metanephrine & normetanephrine are made into?
VMA (vanillymandelic acid)
66
What is made into homovanillic acid (HMA)?
dopamine

USMLE Organ Systems (10 decks)

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