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Biochem - First Aid Flashcards

1
Q

Inhibition of dihydroorotate dehydrogenase

Result?

Pathway?

Use?

A

Leflunomide

Inhibited conversion of carbamoyl phosphate into orotic acid

Pyrimidine synthesis

Rheumatoid arthritis

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2
Q

Inactive/mutate UMP synthase

Result? Pathway?

Symptoms?

IF hyperammonemia instead of refractory anemia?

A

Orotic aciduria

Inhibited conversion of orotic acid to UMP (pyrimidine synthesis)

Orotic acid in urine, megaloblastic anemia refractory to folate and B12 supplementation

Ornithine transcarbamylase deficiency (urea cycle)

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3
Q

Inhibition of ribonucleotide reductase

Result?

Uses?

A

Hydroxyurea

Inhibits DNA (purine and pyrimidine) synthesis

Melanoma, CML, sickle cell disease

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4
Q

Inhibition of thymidylate synthase

Result?

A

5-fluorouracil

Inhibits synthesis of dTMP from dUMP (pyrimidine synthesis)

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5
Q

Inhibition of dihydrofolate reductase (3)

Result?

A

Methotrexate, Trimethoprim, Pyrimethamine

Inhibition of restoration of THF from DHF, thus inhibition of dTMP formation from dUMP (thymidylate synthase)

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6
Q

Inhibition of conversion of PPRP to IMP

Result?

A

6-mercaptopurine, Azathioprine (pro-drug)

Inhibition of purine synthesis (IMP)

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7
Q

Inhibition of inosine monophosphate dehydrogenase (2)

Result?

Use of Mycophenolate?

A

Mycophenolate, Ribavirin

Inhibition of purine synthesis (GMP)

Organ transplant prophylaxis

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8
Q

Adenosine deaminase deficiency

Result?

A

SCID (autosomal recessive)

Impaired purine salvage –> build-up of dATP –> lymphocyte toxicity

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9
Q

Intellectual disability, self-mutilation, aggression, hyperuricemia, orange crystals in diaper, gout, dystonia

Cause?

Result?

A

Lesch-Nyhan syndrome

HGPRT deficiency

Impaired purine salvage (hypoxanthine, guanine) –> excessive uric acid and de novo purine synthesis

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10
Q

Inhibition of xanthine oxidase (2)

Result?

Uses?

A

Allopurinol, Febuxostat

Inhibition of uric acid formation from hypoxanthine (purine degradation)

Lesch-Nyhan, Gout, others

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11
Q

Increased excretion of uric acid

A

Probenecid

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12
Q

Inhibition of prokaryotic topoisomerase II and IV

Other name of topoisomerase II

Normal function?

A

Fluoroquinolones

DNA gyrase

Add single or double strand breaks in DNA helix during replication fork formation to avoid supercoils

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13
Q

Inhibition of eukaryotic topoisomerase II

A

Etoposide, Teniposide

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14
Q

Sickle cell disease…mutation type?

A

Missense (GLU –> VAL)

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15
Q

Duchenne muscular dystrophy…mutation type?

A

Frameshift in DYSTROPHIN (X-recessive)

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16
Q

Tay-Sachs…mutation type?

A

Frameshift in HEXOSAMINIDASE A

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17
Q

Deficient nucleotide excision repair…disease?

Defect?

When does this usually happen?

A

Xeroderma pigmentosum

Endonuclease –> can’t remove damaged DNA bases (UV light) –> neoplasia

G1 phase

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18
Q

Deficient mismatch repair…disease?

What does this mean?

Genes mutated?

When does this usually happen?

A

Lynch syndrome (HNPCC)

Can’t remove mismatched nucleotides after DNA synthesis –> neoplasia (ascending colon, endometrium, other)

MSH, MRH

G2

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19
Q

Deficient repair of double strand DNA breaks…diseases?

A

Ataxia telangiectasia (ATM), Fanconi anemia

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20
Q

Alpha-amanitin

Function? Result?

A

Death cap mushrooms (Amanita phalloides)

Inhibits RNA polymerase 2 (DNA transcription) –> severe hepatotoxicity

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21
Q

Inhibition of prokaryotic RNA polymerase ONLY

Inhibition of prokaryotic AND eukaryotic RNA polymerase

A

Rifampin

Actinomycin D

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22
Q

Anti-Smith antibodies…what are they?

A

Antibodies to spliceosomal snRNPs

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23
Q

Anti-U1 RNP antibodies…what are they?

What disease?

A

Antibodies to a specific spliceosomal snRNP (snRNP70)

Mixed connective tissue disease

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24
Q

Which ribosome subunits are eukaryotic vs prokaryotic?

How to remember?

A 
Eukaryotic = 40S and 60S
Prokaryotic = 30S and 50S
Eukaryotes = Even
prOkaryotes = Odd
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25
Q

Permanent cell types

A

Neurons, skeletal muscle, cardiac muscle, RBCs

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26
Q

Stable cell types

A

Hepatocytes, lymphocytes

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27
Q

Labile cell types

Importance?

A

BM, gut epithelium, skin, hair follicles, germ cells

MOST affected by chemotherapy

28
Q

Coarse facial features, clouded corneas, restricted joint movement, high plasma levels of lysosomal enzymes

Explain

A

I-Cell Disease

Defect in N-acetylglucosaminyl-1-phosphotransferase

Failure of Golgi to add mannose-6-phophate to lysosome-bound enzymes –> get released into extracellular space

29
Q

Vimentin

Desmin

Cytokeratin

GFAP

Neurofilaments

A

Mesenchymal tissue (ex. sarcoma)

Muscle (ex. rhabdomyosarcoma)

Epithelial (ex. SCC)

Neuroglia (astrocytoma, glioblastoma)

Neurons (ex. neuroblastoma)

30
Q

Drugs that inhibit microtubules (6)

A 
Mebendazole (helminth)
Griseofulvin (fungal)
Colchicine (gout)
Vincristine (cancer)
Vinblastine (cancer)
Paclitaxel (cancer)
31
Q

2 molecular motor proteins

What do they do?

A

Dynein (retrograde), Kinesin (anterograde)

Move things along the microtubule

32
Q

Defective dynein (ATPase) in cilia

A

Kartagener syndrome (primary ciliary dyskinesia)

33
Q

Inhibition of K+ binding site of Na-K ATPase

A

Ouabain

34
Q

Direct inhibition of the Na-K ATPase

Result?

A

Cardiac glycosides (digoxin, digitoxin)

Inhibition of Na/Ca exchanger –> increased Ca++ –> increased cardiac contractility

35
Q

Deficient type 1 collagen

Where is it used?

A

Osteogenesis imperfecta type 1

Bone, skin, tendon, dentin, fascia, cornea, late wound repair

36
Q

Deficient type 3 collagen

Where is it used?

A

Ehlers-Danlos (vascular type) – vascular and organ rupture symptoms

Skin, BLOOD VESSELS, uterus, fetal tissue, granulation tissue

37
Q

Deficient/destroyed type 4 collagen (2)

Where is it used?

A

Alport syndrome, Goodpasture syndrome

Basement membrane, basal lamina, lens

38
Q

Deficient hydroxylation of proline and lysine residues

What process?

A

Scurvy (requires Vitamin C as cofactor)

Collagen synthesis

39
Q

Deficient glycosylation of pro-alpha-chain hydroxylysine residues (forming triple helix)

Genes?

What process?

A

Osteogenesis imperfecta

COL1A1, COL1A2

Collagen synthesis (procollagen formation)

40
Q

Deficient lysine-hydroxylysine cross-linking (2)

Enzyme? Needs what?

What process?

A

Ehlers-Danlos, Menkes disease

Lysyl oxidase – needs COPPER

Collagen synthesis (collagen fibril formation)

41
Q

Deficient type 5 collagen

A

Ehlers-Danlos (classical type) – joint and skin symptoms

42
Q

Brittle kinky hair, growth retardation, tortuous arteries, hypotonia

Cause?

Findings?

A

Menkes disease

ATP7A mutation –> impaired copper absorption and transport –> dysfunctional lysyl oxidase –> poor collagen

Low ceruloplasmin

43
Q

Defect in a glycoprotein that forms a sheath around elasin

What is the defect?

A

Marfan syndrome

Fibrillin

44
Q

Excessive elastase (elastin breakdown) activity

A

Alpha-1 antitrypsin deficiency

45
Q

Decreased production of collagen and elastin in the skin over time

A

Wrinkles (aging)

46
Q

PCR commonly used to diagnose what? (2)

A

Neonatal HIV, herpes encephalitis

47
Q

Confirmatory test for HIV after ELISA

A

Western blot

48
Q

Ordering, numbering, and staining chromosomes during metaphase

A

Karyotyping

49
Q

Lab electrophoresis test between a protein and a DNA probe

A

Southwestern blot

50
Q

Blood group alleles are a good example of ____

A

Codominance (both contribute to phenotype)

51
Q

2 patients with NF1 have different degrees of the disease

A

Variable expressivity

52
Q

Not everyone with the BRCA1 mutation has breast cancer

A

Incomplete penetrance

53
Q

Mutations in PKU, Marfans, and CF cause a wide variety of symptoms across multiple organ systems

A

Pleiotropy

54
Q

The onset of Huntington’s gets earlier each generation

A

Anticipation

55
Q

A patient with an inherited RB mutation eventually develops a full-on retinoblastoma or osteosarcoma

A

Loss of heterozygosity

56
Q

Unilateral brown macules on skin
Malformation of bones
Precocious puberty
Endocrine anomalies

If alive, what must be the case?

Mutation?

A

McCune-Albright syndrome

Must be a MOSAIC (fatal if before fertilization)

Mutated G-protein signaling

57
Q

A patient w/ Downs syndrome tests negative, then later tests positive on skin cell sampling…explanation?

A

MOSAIC (1-3% of cases)

58
Q

Presence of normal AND mutated mitochondrial DNA, causing variable expressivity of mtDNA disease

A

Heteroplasmy

59
Q

X-linked recessive disease…

  • Frequency of the disease in males?
  • Frequency of the disease in females?
A 
Males = q
Females = q^2
60
Q

Hyperphagia, obesity, intellectual disability, hypogonadism, hypotonia

Causes?

A

Prader-Willi syndrome

75% = Imprinting of maternal gene, loss of paternal gene
25% = Uniparental disomy (both imprinted maternal genes)
61
Q

Inappropriate laughter, seizures, ataxia, intellectual disability

Causes?

A

Angelman syndrome

95% = Imprinting of paternal gene, loss of maternal gene
5% = Uniparental disomy (both imprinted paternal genes)
62
Q

Imprinting…what is it?

A

Cytosine methylation of a gene, thus silencing it

63
Q

Diseases of ____ are often pleotropic and variably expressed

A

Autosomal dominant

64
Q

Ragged red fibers…inheritance?

A

Mitochondrial

65
Q

Algorithm for determining inheritance pattern?

A
  1. Is parent affected? (Y = dominant, N = recessive)
    2a. Male to male transmission? (Y = Auto dominant, N = X-Dominant)
    2b. All/mostly males? (Y = X-recessive, N = auto recessive)
66
Q

Short stature, normal head/torso

Mutation? Inheritance?

A

Achondroplasia

FGFR3 – autosomal dominant

67
Q

**How does alcohol consumption cause hypoglycemia?

A

Uses NAD+ to be metabolized to acetic acid. Low NAD+ and high NADH cause impaired gluconeogenesis due the shift of 3 metabolic reactions…

- DHAP --> glycerol-3P
- Pyruvate --> lactate
- Oxaloacetate --> malate

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