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Step I > molecular biochem > Flashcards

molecular biochem Flashcards

1
Q

histones

A

rich in lysine and arginine
positive charge for neg DNA to wrap around
Methylation -> mute
acetylation -> active

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2
Q

heterochromatin

A 
HeterChromatin = Highly Condensed
Barr bodies (inactivated X)
Darker on EM
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3
Q

Euchromatine

A

Eu = true = truly transcribed

light on EM

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4
Q

Pyrimadines

A

C-U-T the py

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5
Q

purines

A

pure As Gold

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6
Q

which nucleotide has a mehtyl

A

Thymine

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7
Q

which nucleotide bond is stronger

A

G-C

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8
Q

which aa are necessary fro purine synthesis?

A

GAG
glycine
aspartate
glutamine

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9
Q

NucleoSide

A

base + deoxyribose (Sugar)

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10
Q

NucleoTide

A

nucleoside + phosphaTe

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11
Q

leflunomide

A

inhibits dihydroorotate dehydrogenase
cannot make ortic acid from carbamoyl phosphate and aspartate
therefore cannot make pyrimadines

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12
Q

mycophenolate and ribavirin

A

inhibit IMP dehydrogenase

cannot make GMP from IMP

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13
Q

hydroxyurea

A

inhibits ribonucloside reductase
cannot make dUMP from UDP
therefore cannot make dTMP

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14
Q

5-FU

A

inhibits thymidylate synthase

cannot make dTMP

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15
Q

which drugs inhibits Dihydrofolate reductase

A

MTX
TMP
pyrimethamine
cannot regenerate THF therefore cannot make dTMP

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16
Q

what step of nucleotide synthesis is imparied in ortic aciduria?

A

cannot combine ortic acid w/aspartate to make UMP

cannot make pyrimidines

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17
Q

adenosine deaminase deficiency

A

excess ATP and dATP -> feedback inhibition of DNA synthesis -> decreased lymphocyte counts
major cause of AR SCIDs

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18
Q

Lesch-Nyhan syndrome

A

defective purine salvage d/t absent HGPRT
excess uric acid production and de novo purine synthesis
x-linked recessive
Tx: allopurinol or febuxostat (2nd line)

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19
Q

HGPRT acroynm

A 
Hyperuricemia
Gout
Pissed off (aggressive, self-mutilation)
Retardation
dysTonia
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20
Q

allopurinol and febuoxostat

A

xanthine oxidase inhibitors cannot make uric acid

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21
Q

probenecid

A

increases excretion of uric acid in urine

22
Q

DNA topoisomerase

A

create a single or double stranded break in helix to add or remover super coils
type II/DNA gyrase and type IV inhibited by fluoroquinolones

23
Q

DNA polymerase III

A

prokaryotic only
elongates laggin strand until it reaches primer of preceding fragments
5’-3’ synthesis
3’-5’ proof reading

24
Q

DNA polymerase I

A

prokaryotic only
degrades DNA primer and replaces it with DNA
same as III, but ecises RNA primers w/5’-3’ exonuclease

25
Q

telomerase

A

RNA-dependent DNA polymerase that adds DNA to 3’ end of chormosomes to avoid loss of genetic material w/duplication
Eukaryotes only

26
Q

Lac operon

A

E. coli, increases lactose metabolism when needed
low glucose -> increased AC -> increased cAMP -> activation CAP -> increased transcription
high lactose -> unbinds repressor protein -> increased transcription

27
Q

nucleotide excision repair

A

endoneucleases release oligonucelotides w/damaged bases
repairs bulky helix distorting lesions (UV damage)
G1 phase
defective in xeroderm pigmentosum

28
Q

xeroderma pigmentosum

A

prevents repair of pyrimidine dimers d/t UV exposure

29
Q

base excision repair

A

base-specific glycosylase removes altered base
thru-out cell cycle
important in repair of spontaneous/toxic deamination

30
Q

mismatch repair

A

mismatched nucleotides are removed
G2 phase
defective in hereditary non-polyposis colorectal cancer (HNPCC)

31
Q

nonhomologous end joining

A

repairs double stranded breaks
some DNA ma be lost
mutated in ataxia telangiectasia and fanconi anemia

32
Q

DNA/RNA/protein synthesis direction

A

DNA and RNA are both synthesized 5’ -> 3’
5’ end bares triphosphate (energy for bond)
protein synthesis N->C
mRNA read 5’ -> 3’

33
Q

mRNA codones

A

AUG (inAUGurates synthesis)
rarely GUG
in eukaryotes codes for methionine
in prokaryotes codes for fMet

34
Q

mRNA stop codones

A

UGA
UAA
UAG

35
Q

promoter sequence

A

TATA box
RNA polymerase II binds
mutations usually result in dramatic decrease in gene transcription

36
Q

RNA polymerase I

A

makes rRNA (most numerous/Rampant)

37
Q

RNA polymerase II

A 
makes mRNA (largest/massive)
opens DNA at promoter site
38
Q

RNA polymerase III

A

makes tRNA (smallest/tiny)

39
Q

RNA polymerases

A

do not have proof reading ability

prokaryotes have 1 polymerase w/all 3 fnxs

40
Q

alpha-amanitin

A

found in amansita phalloides (death cap mushrooms)

inhibits RNA polymerase -> severe hepatotoxcity

41
Q

rifampin

A

inhibits prokaryote RNA polymerase

42
Q

actinomycin D

A

inhibits RNA polymerases in both prokaryotes and eukaryotes

43
Q

RNA processing in eukaryotes

A

initial transcript is hnRNA which is modified:

  • capping of 5’ end
  • polyadenylation of 3’
  • splicing of introns
  • > mRNA -> transported into cyto for translation
44
Q

anti-snRNPs

A

aka Smith Abs

SLE

45
Q

anti-U1 RNP abs

A

mixed CT disease

46
Q

tRNA structrue

A

cloverleaf form
anti-codon end opposite 3/ aminoacyl end
CCA at 3’ end (Can Carry Aa)

47
Q

charging of tRNA

A

aminoacyl-tRNA synthetase checks to make sure matchis correct

48
Q

wobble

A

accuracy only required for first two base-pairs

49
Q

protein synthesis initiation

A

initiated by GTP hyrolysis, initiation factors help assemble 40s, released when 60s binds

50
Q

elongation

A

aminoacyl-tRNA binds to site A
rRNA catalyzes peptide bond
riboseoms advances 3 nucleotides toward 3’ end of mRNA

Step I (22 decks)

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