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UWorld Review > Molecular biochem > Flashcards

Molecular biochem Flashcards

1
Q

AA necessary for purine synthesis

A

glycine
aspartate
glutamine

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2
Q

term: most AA are coded by multiple codons

A

Degenerate/redundant

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3
Q

what AA are only coded by one codon

A

methionine (AUG)

tryptophan (UGG)

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4
Q

term: each condone specifies only 1 AA

A

unambiguous

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5
Q

term: read from a fixed starting point as a continuous sequence of bases

A

comma less
nonoverlapping
exceptions: some viruses

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6
Q

In both prokaryotes and eukaryotes, DNA replication is

A

semiconservative
both continuous and discontinuous (Okazaki fragments)
5’ to 3’ direction

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7
Q

Bloom syndrome (BLM gene mutation)

A

helicase deficiency

cannot unwind DNA template at replication fork

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8
Q

Makes RNA primer so DNA polymerase III can initiate replication

A

Primase

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9
Q

Prevents strands from reannealing

A

single-stranded binding proteins

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10
Q

DNA polymerases that prokaryotes only have

A

Polymerase I and III

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11
Q

Create single or double stranded break in helix to add or remove supercoils

A

DNA topoisomerase

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12
Q

Irinotecan/topotecan MOA

A

(eukaryote) inhibit topoisomerase I

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13
Q

etoposide/teniposide MOA

A

(eukaryote) inhibit topoisomerase II

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14
Q

fluoroquinolone MOA

A

(prokaryotes) inhibit TOP II (DNA gyrase) and TOP IV

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15
Q
  • Elongates leading strand by adding deoxynucleotides to 3’ end
  • Elongates lagging strand until reaches primer of preceding fragment
A

DNA polymerase III

prokaryotes only

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16
Q

DNA polymerase III synthesizes in what direction

A

5’ to 3’

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17
Q

DNA polymerase III proofreads in what direction

A

3’ to 5’ exonuclease

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18
Q

Drugs blocking DNA replication often have

A

modified 3’ OH that prevents addition of next nucleotide = chain termination

affects DNA polymerase III

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19
Q

Degrades RNA primer and replaces w/DNA

A

DNA polymerase I
prokaryotes only
same functions as DNA polymerase III
excises RNA primer w/ 5’ to 3’ exonuclease

20
Q

T or F: All prokaryotic DNA polymerases can proofread using 3’ to 5’ exonuclease activity

A

True

21
Q

Reverse transcriptase (RNA dependent DNA polymerase) that adds DNA (TTAGGG) to 3’ end of chromosomes to avoid loss of genetic material w/every duplication

A

telomerase

eukaryotes only

22
Q

what is often dysregulated in cancer cells, allowing unlimited replication

A

telomerase

23
Q

RNA processing that happens in the nucleus

A

capping of 5’ end w/7-methylguanosine cap
polyadenylation of 3’ end
splicing out introns

24
Q

mRNA quality control occurs at

A

cytoplasmic processing bodies (P-bodies)

25
Q

P-bodies contain

A

exonucleases
decapping enzymes
microRNAs
mRNA may be degraded or stored in P-bodies for future translation

26
Q

fMet in prokaryotes stimulates

A

neutrophils chemotaxis

27
Q

transcription and translation occurs in (gene expression)

A

G1, S, G2

never in M

28
Q

Chemodrugs that affect S phase

A

5-FU (inhibits thymidylate synthase)

MTX (inhibits DHF reductase)

29
Q

Chemodrugs that affect G2 phase

A

Bleomycin
Hodgkin lymphoma
causes pulmonary fibrosis

30
Q

Chemodrugs that affect S phase

A

Paclitaxel
Vincristine
Vinblastine

31
Q

Chemodrugs that are non-cell cycle dependent

A

cyclophosphamide
cisplatin
(blocks cycle nonspecifically)

32
Q

DNA replication occurs during

A

S phase

33
Q

Lynch syndrome (hereditary nonpolyposis colorectal cancer) has defect in what kind of DNA repair

A 
Mismatch repair (single strand)
S phase
34
Q

Dry skin, extreme light sensitivity, skin cancer has defect in what kind of DNA repair

A

nucleotide excision repair (single strand)

G1 phase

35
Q

DNA repair important for spontaneous/toxic deamination

A

Base excision repair (single strand)

throughout cell cycle

36
Q

Ataxia-telangiectasia has defect in what kind of DNA repair

A

Nonhomolgous end joining (double strand)

37
Q

Brings 2 ends of DNA fragments to repair double strand breaks

  • no homology requirement
  • some DNA may be lost
A

Nonhomologous end joining (double strand)

38
Q

Requires two homologous DNA duplexes

  • strand from damaged dsDNA repaired using complementary strand from intact homologous dsDNA as template
  • restores duplexes accurately without loss of nucleotides
A

Homologous recombination (double strand)

39
Q

Breast/ovarian cancer w/BRCA1 mutation and Fanconi anemia have defect in what kind of DNA repair

A

Homologous recombination (double strand)

40
Q

alpha-amanitin found in Amanita phalloides death cap mushrooms inhibits

A

RNA polymerase II = no mRNA

severe hepatotoxicity

41
Q

Actinomycin D or dactinomycin inhibits

A

RNA polymerase in both prokaryotes and eukaryotes

42
Q

variants in splicing occurs in oncogenesis and many genetic disorders

A

beta thalessemia
Gaucher disease
Tay-sachs disease
Marfan syndrome

43
Q

microRNAs are

A
  • small non-coding RNA
  • post transcriptionally regulate gene expression
  • targets 3’ untranslated region of specific mRNA for degradation or translational repression
44
Q

Part of tRNA necessary for tRNA ribosome binding

A

T-arm

45
Q

Part of tRNA that has dihydrouridine residues necessary for tRNA recognition by correct aminoacyl tRNA synthetase

A

D-arm

UWorld Review (35 decks)

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