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Boards Biochem > Molecular > Flashcards

Molecular Flashcards

0
Q

2 a.a. that histones are rich in

A

Lysine & arginine

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1
Q

neg charged DNA that loops around positively charged histone octamer consisting of [H2A, H2B, H3, H4] x 2

A

nucleosome

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2
Q

what histone binds to the nucleosome and to linker DNA to stabilize chromatin fiber

A

H1

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4
Q

3 necessary a.a. for purine synthesis

A

glycine, aspartate, glutamine

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5
Q

enzyme that converts ribonucleotides to deoxyribonucleotides in pyrimidine synthesis

A

ribonucleotide reductase

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6
Q

carbamoyl phosphate is involved in which 2 metabolic pathways…

A

de novo pyrimidine synthesis

urea cycle

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7
Q

drug that inhibits dihydroorotate dehydrogenase causing a build up of carbamoyl phosphate and low orotic acid (pyrimidine synth)

A

Leflunomide

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8
Q

2 drugs that inhibit IMP dehydrogenase in purine synthesis

A

Mycophenolate

Ribavirin

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9
Q

drug that inhibits ribonucleotide reductase

A

hydroxyurea

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10
Q

2 drugs that inhibit de novo purine synthesis

A

6-mercaptopurine & it’s pro drug azathioprine

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11
Q

drug that inhibits thymidylate synthase thereby decreasing dTMP

A

5-fluorouracil

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12
Q

3 drugs that inhibit dihydrofolate reductase (decr dTMP) in humans, bacteria, protozoa

A

humans- methotrexate
bacteria- TMP
protozoa- pyrimethamine

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13
Q

auto recessive deficiency of adenosine deaminase: excess ATP & dATP causes feedback inhib of ribonucleotide reductase - prevents DNA synth - lowers lymphocyte count

A

SCID

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14
Q

defective purine salvage d/t absent HGPRT which converts hypoxanthine to IMP and guanine to GMP to recycle purines - results in excess uric acid & de novo purine synth
X linked recessive
causes intellect disability, self mutilation, aggression, hyperuricemia, gout, dystonia

A

Lesch Nyhan syndrome

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15
Q

AUG

A

methionine start codon in eukaryotes

codes for N-formylmethionine in prokaryotes - stimulates neutrophil chemotaxis

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16
Q

UGG

A

tryptophan

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17
Q

drug that inhibits prokaryotic enzyme topoisomerase II & IV

A

fluoroquinolones

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18
Q

prokaryotic DNApol with 5’ to 3’ synth and 3’ to 5’ exonuclease proofreading

A

DNA polymerase III

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19
Q

prokaryotic DNApol that degrades RNA primer & replaces it with DNA
same functions as DNApol III but also excises RNA primer with 5’ to 3’ exonuclease

A

DNA polymerase I

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20
Q

catalyzes formation of phosphodiester bond within a strand of dsDNA (joints Okazaki fragments)

A

DNA ligase

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21
Q

RNA-dependent DNA pol that adds DNA to 3’ ends of chrom to avoid loss of genetic material with every duplication (euk only)

A

telomerase

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22
Q

DNA mutation with nt substitution causing changed a.a.

A

missense point mutation

23
Q

DNA mutation with nt substitution causing early stop codon

A

nonsense point mutation

24
Q

low glucose - incr adenylyl cyclase activity - incr generation of cAMP from ATP - activates catabolite activator protein - transcription increases

A

MOA for lac operon in E. coli with glucose absent to do lactose metabolism

25
Q

high lactose - unbinds repressor protein from repressor/operator site - transcription increases

A

MOA for lac operon in E. coli with high lactose to do lactose metabolism

26
Q

defective nt excision repair in G1 preventing repair of pyrimidine dimers from UV light exposure

A

xeroderma pigmentosum

27
Q

defective mismatch repair in G2 phase of cell cycyle

A

hereditary nonpolyposis colorectal cancer

28
Q

mutated non homologous end joining to bring together 2 ends of DNA fragments to repair ds breaks

A

ataxia telangiectasia

Fanconi anemia

29
Q

UGA, UAA, UAG

A

mRNA stop codons
‘U Go Away’
‘U Are Away’
‘U Are Gone’

30
Q

RNA polymerase I

A

makes rRNA in eukaryotes

31
Q

RNA polymerase II

A

makes mRNA in eukaryotes

opens DNA at promoter site

32
Q

RNA polymerase III

A

makes tRNA in eukaryotes

33
Q

toxin found in Amanita phalloides (death cap mushrooms) that inhib RNApol II - causes severe hepatotoxicity

A

alpha amanitin

34
Q

drug that inhibits RNApol in prok

A

Rifampin

35
Q

drug that inhib RNApol in both prok & euk

A

Actinomycin D

36
Q

prokaryotic RNA polymerase

A

1 RNA polymerase (multisubunit complex) makes all 3 kinds of RNA

37
Q

processes that occur in the nucleus to hnRNA to modify it into mRNA

A

capping of 5’ end (add 7-methylguanosine cap)
polyadenylation of 3’ end (AAUAAA)
splicing out introns

38
Q

where does translation occur in the cell?

A

cytosol

39
Q

function of snRNPs in spliceosome forming a lariat

A

splicing of pre-mRNA to remove introns

40
Q

Ab to spliceosomal snRNPs

A

anti-Smith Ab highly specific for SLE

41
Q

anti-U1 RNP Ab

A

mixed connective tissue disease

42
Q

3 base sequence at 3’ end of all tRNA’s to which the a.a. binds

A

CCA

43
Q

T arm of tRNA

A

thymine, pseudouracil, cytosine

necessary for tRNA-ribosome binding

44
Q

D arm of tRNA

A

dihydrouracil residues needed for tRNA recognition by correct aminoacyl-tRNA synthetase

45
Q

aminoacyl-tRNA synthetase

A

1 per a.a.

uses ATP to check a.a. before & after binding tRNA (if incorrect, it hydrolyzes the bond)

46
Q

GTP hydrolysis with initiation factors to assemble 40S with initiator tRNA

A

protein synthesis initiation

47
Q

eukaryotic ribosomes

A

40S + 60S = 80S

48
Q

prokaryotic ribosomes

A

30S + 50S = 70S

49
Q

protein synthesis elongation A site

A

aminoacyl-tRNA binds here (except for methionine)

50
Q

protein synthesis elongation P site

A

accommodates growing peptide - peptide bond formation

51
Q

protein synthesis elongation E site

A

holds empty tRNA as it exits (translocation)

52
Q

removal of N- or C-terminal propeptides from zymogen to make mature protein

A

trimming posttranslational modification

53
Q

intracell protein that facilitates protein folding

A

chaperone proteins

Boards Biochem (6 decks)

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