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Flashcards in Biochem Deck (48)
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1
Q

α-amanitin

A
  • found in death cap mushroom.
  • inhibits RNA pol 2 (makes mRNA).
  • hepatotoxic.
2
Q

P-bodies

A
  • mRNA quality control.
  • cytoplasmic.
  • contain exonucleases, decapping enzymes, and microRNAs
  • mRNAs may be stored here for future translation.
3
Q

spliceosomal snRNPs

A
  • Abs against these = anti-smith Abs

- specific for SLE

4
Q

Trimming

A
  • post-translational modification.

- Removal of N- or C-terminal propeptides from zymogen to generate mature protein (e.g., trypsinogen to trypsin).

5
Q

Ingredients to make Niacin (B3)

A

Tryptophan
B2 (riboflavin)
B6 (pyridoxine)

6
Q

Base excision repair

A
1-glycosylase = strips off base
2-endonuclease = cleaves 5' end
3-lyase = cleaves 3' end
4-DNA pol
5-ligase
7
Q

Enhancers and silencers (of gene expression)

A

Variable locations

8
Q

COP1

A

Retrograde

  • Golgi => Golgi
  • Golgi => ER
9
Q

COP2

A

Anterograde

  • Golgi => Golgi
  • ER => Golgi
10
Q

Ribozyme (rRNA)

A

Catalyzes peptide bond formation btwn amino acids

11
Q

Ouabain

A

Inhibits Na/K ATPase by binding to K site.

12
Q

Type 3 Cartilage

A

Reticulin:

  • blood vessels
  • uterus
  • fetal tissue
  • granulation tissue
13
Q

Problems forming triple helix in RER (collagen).

A

Osteogenesis imperfecta

14
Q

Problems cross-linking collagen (lysyl oxidase)

A

Ehlers Danlos

15
Q

Menkes Disease

A
  • CT disease
  • impaired copper absorption and transport.
  • leads to dec. lysyl oxidase activity (cross links collagen)
  • brittle, “kinky” hair, growth retardation and hypotonia.
16
Q

Pleiotropy

A

One gene contributes to multiple phenotypic effects.

ie. PKU

17
Q

Dominant negative mutation

A

Exerts a dominant effect. A heterozygote produces a nonfunctional altered protein that also prevents the normal gene product from functioning.
-Mutation of a transcription factor in its allosteric site. Nonfunctioning mutant can still bind DNA, preventing wild-type transcription factor from binding.

18
Q

McCune-Albright syndrome

A

-lethal if themutation is somatic, but survivable if mosaic.
-polyostotic fibrous dysplasia with cafe-au-lait skin
pigmentation and endocrinopathies.

19
Q

Locus heterogeneity

A

Mutations at different loci can produce a similar
phenotype.
-ie. albinism

20
Q

Allelic heterogeneity

A

Different mutations in the same locus produce the same phenotype.
-ie. beta-thal

21
Q

Heteroplasmy

A

Presence of both normal and mutated mtDNA, resulting in variable expression in mitochondrial inherited disease.

22
Q

Heterodisomy

A

meiosis 1 error

23
Q

Isodisomy

A

meiosis 2 error

24
Q

Prader-Willi & angelman

-which chromosome?

A

15

-or uniparental disomy. Inherit two methylated copies.

25
Q

Hypophosphatemic rickets

A

Formerly known as vitamin D–resistant rickets. Inherited disorder resulting in  phosphate wasting at proximal
tubule. Results in rickets-like presentation.

26
Q

Mitochondrial myopathies

A

rare disorders; often present with myopathy, lactic acidosis and CNS disease. 2° to failure in oxidative
phosphorylation. Muscle biopsy often shows “ragged red fibers.”

27
Q

FAP

-which chromosome?

A

5

-5 letters in “polyp”.

28
Q

Osler-Weber-Rendu Syndrome

A

aka Hereditary hemorrhagic telangiectasia

  • Inherited disorder of blood vessels.
  • Findings: telangiectasia, recurrent epistaxis, skin discolorations, arteriovenous malformations (AVMs), GI bleeding, hematuria.
29
Q

NF1

-which chrom?

A

17

-17 letters in “von Recklinghausen.”

30
Q

NF2

-which chrom?

A

22

-NF2 = 22

31
Q

VHL

-which chrom?

A

3

-VHL = 3 letters

32
Q

Hardy Weinberg

A

The frequency of an X-linked recessive disease

in males = q and in females = q^2.

33
Q

Cystic Fibrosis

A
  • infertility in males due to abscence of vas deferens and therefore absent sperm.
  • Tx of CF = N-acetylcysteine, dornase alfa
34
Q

Duchenne MD

A
  • Frameshift mutation

- Dilated cardiomyopathy = common cause of death.

35
Q

Becker MD

A

-X-linked point mutation

36
Q

Myotonic type 1 MD

A
  • CTG trinuc. repeat in DMPK gene.
  • abnormal expression of myotonin protein kinase.
  • frontal balding, testicular atrophy, arrythmia.
37
Q

Fragile X

-whats the trinuc?

A

CGG

38
Q

Down’s Syndrome

A

-Brushfield spots, gap btwn first 2 toes, hirschsprungs.
-meiotic nondisjunction, robertsonian translocation, mosaicism.
-First-trimester ultrasound commonly shows:
 nuchal translucency and hypoplastic nasal
bone; dec. PAPP-A, inc. b-hCG.
-Second-trimester quad screen shows:
 dec. α-fetoprotein, inc. b-hCG,  dec. estriol, inc.
 inhibin A.

39
Q

Edwards syndrome

A
  • micrognathia, low set ears, congenital heart disease, clenched hands,
  • PAPP-A and b-HCG = both dec in 1st trimester.
  • Quad screen: everything dec. (AFP, B-hCG, estriol, inhibin A).
40
Q

Patau syndrome

A
  • microphthalmia, microcephaly, cleft lip/palate, holoprosencephaly, polydactyly, congenital heart disease.
  • dec. b-hcg & PAPP-A.
  • inc. nuchal translucency.
41
Q

Cri-du-chat syndrome

A

-5p microdeletion
-microcephaly, intellectual disability, high-pitched
crying/mewing, epicanthal folds, cardiac abnormalities (VSD).

42
Q

Williams syndrome

A
  • 7q microdeletion (incl. elastin gene).
  • “elfin” facies, intellectual disability, hypercalcemia (sensitivity to vitamin D), well-developed verbal skills, extreme friendliness with strangers, cardiovascular problems.
43
Q

Vitamin A

A

treates measles & AML-M3

44
Q

B2 deficiency

A

Cheilosis, Corneal vascularization.

45
Q

Vitamin C: uses

A
  • Reduces ferric to ferrous
  • hydroxylation of lysine & proline
  • dopamine => NE
46
Q

Vitamin E

A

-can enhance anti-coag effects of warfarin. May lead to bleeding problems.

47
Q

hyPOphosphorylated Rb

A
  • No passage from G1 to S.
  • Cell stopped.
  • Abnormal cell.
48
Q

hyPERphosphorylatd Rb

A
  • inactive
  • Cell can progress
  • everything is normal