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M2M Biochemistry and molecular biology > Translation LO > Flashcards

Translation LO Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is the central dogma?

A

DNA to RNA to Protein

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2
Q

how many high-energy bonds are formed for each peptide bond?

A

4

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3
Q

True of False

the basic process of translation is highly conserved between all forms of life

A

True

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4
Q

what is the function of messenger RNA (mRNA)?

A

carries codons that code for the amino acid sequence of a protein

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5
Q

how many possible codons are there?

A

4^3= 64 possible codons

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6
Q

What is the start codon?

A

AUG

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7
Q

what are the “non-sense” or stop codons on RNA?

A

UGA
UAA
UAG

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8
Q

what is the function of transfer RNA (tRNA)?

A

“read” the message and deliver the right amino acid to the ribosome

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9
Q

what dictates the function of tRNA?

A

the three-dimensional folded structure

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10
Q

why can some tRNA’s recognize more than one codon?

A

wobble-pairing at the third location on the codon

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11
Q

what is the function of aminoacyl tRNA synthetases?

A

protein enzymes that put the right amino acid on the right tRNA

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12
Q

what is the function of the ribosome?

A

catalytic center for translation

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13
Q

what synthetase puts a valine on a val-tRNA?

A

valyl-tRNA synthetase

aminoacid-tRNA synthetase

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14
Q

what are the 2 subunits in prokaryotic ribosomes?

A

30S and 50S

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15
Q

what are the 2 subunits in eukaryotic ribosomes?

A

30S and 60S

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16
Q

which subunit contains the catalytic center?

A

the large subunit

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17
Q

what is another name for the catalytic center of a ribosome?

A

peptidyl transferase center (PTR)

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18
Q

what type of enzyme is a ribosome and why?

A

ribozyme because it uses RNA to perform catalysis

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19
Q

what is the function of initiating factors in translation?

A

bring ribosome to the message and assist in getting the machinery assembled

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20
Q

what is the function of elongation factors and their partners?

A

deliver tRNAs and move ribosome down the message

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21
Q

what is the function of termination/recycling factors?

A

end the process at stop codon, disassociate subunits so they can be used again

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22
Q

where is the amino acid attached on tRNA?

A

the acceptor stem

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23
Q

which portion of the tRNA reads the mRNA?

A

anticodon loop

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24
Q

what is the start codon and which amino acid does it code for?

A

AUG

methionine

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25
Q

what is the final assembled ribosome called in prokaryotes?

A

70S

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26
Q

what is the final assembled ribosome called in eukaryotes?

A

80S

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27
Q

how many tRNA binding sites does a ribosome have?

A

3

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28
Q

what are the 3 binding sites on a ribosome?

A

A- aminoacyl site
P - peptidyl site
E - exit site

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29
Q

what are the 4 phases of translation?

A
  1. initiation
  2. elongation
  3. termination
  4. ribosome recycling
30
Q

which step in translation differs the most between eurkaryotes and prokaryotes?

A

initiation

31
Q

what is the point of the initiation step?

A

assemble ribosome at start codon (AUG) with initiator methionine tRNA in P-site and next aa-tRNA in the A-site

32
Q

what initiation factor proteins are used in prokaryotes to bind the 30S subunit?

A

IF1 and IF3

33
Q

what is the function of IF2 in prokaryotes?

A

delivers special “initiator” formylmethionine tRNA to P-site to pair with AUG codon

34
Q

what does GTP hydrolysis of IF2 lead to?

A

release of all initiation factors and binding of 50S subunit forming 70S ribosome

35
Q

why does the ribosome in prokaryotes bind directly to the AUG codon?

A

Shine-Dalgarno sequence about 8 bp upstream from AUG codon

36
Q

what initiation factor in eukaryotes binds the 7-methyl guanosine cap to the 5’ end of RNA?

A

4E

37
Q

what does polycistronic mean?

A

mRNA can have many genes expressed on just one strand such as in prokaryotes (have many shine-dalgarno sites) (lac operon)

38
Q

how is eukaryotic initiation different than prokaryotic initiation?

A

eukaryotic more complex, ribosome scans downstream to find AUG codon after small subunit binds and then large subunit can bind, prokaryotes bind directly to AUG codon

39
Q

which step of translation is considered to have the most control and regulation?

A

initiation

40
Q

what is elongation?

A

moving along the mRNA and making the encoded protein

41
Q

where does the energy for peptide bond formation come from?

A

ATP used in tRNA charging

42
Q

what moves the mRNA and tRNAs exactly one codon in the 3’ direction?

A

EF2 and GTP hydrolysis

43
Q

what are the 4 high energy bonds expended to form a peptide bond?

A
  1. charge tRNA (2 ATP to AMP)
  2. deliver aa-tRNA to A site (1 GTP to GDP)
  3. translocation (1 GTP to GDP)
44
Q

which factors bind to the stop codon and terminate the polypeptide synthesis?

A

release factors

45
Q

what is a missense mutation?

A

mutation resulting in amino acid change

46
Q

what is a silent mutation?

A

codon is changed but same amino acid is encoded (the mutation is in the wobble position)

47
Q

what is a frame-shift mutation?

A

an addition or deletion of a nucleotide causes a shift in the reading frame

48
Q

what is a non-sense mutation?

A

mutation resulting in a premature stop codon

49
Q

what is a sense mutation?

A

mutation resulting in a removed stopped codon

50
Q

what mutation is Hemoglobin Wayne a result of?

A

3’ terminal frameshift mutation

51
Q

what mutation is Hemoglobin Constant Spring a result of?

A

Sense mutation (UAA stop to CAA Gln)+

52
Q

what presentation do both Hemoglobin Wayne and Hemoglobin Constant Spring have?

A

chronic anemia

53
Q

why can production of protein be slowed if a mutation gives rise to a “rare” codon?

A

because there are a limited number of tRNA for each amino acid

54
Q

what determines the strength of expression of different AUG’s in eukaryotes?

A

Kozak Context

55
Q

what is RNA editing and why is it significant?

A

transcribed RNA modified so that coding is affected. important because some proteins are tissue specific, can have 2 types of protein from 1 gene that is tissue specific (apoB)

56
Q

transferrin

A

binds iron

57
Q

transferrin receptor (TFR)

A

transports Fe into the cell

58
Q

ferritin

A

sequesters excess FE

59
Q

iron repsponse element (IRE)

A

RNA stem-loop structure found in mRNAs that can bind to IRPs

60
Q

Irons Response Binding proteins (IRE-BPs) 1 and 2

A

bind FE and regulate expression of ferritin and TFR

61
Q

under high Fe conditions, what is the relationship between IRE-BPs, Fe, and IRE RNA

A

IRE-BPs bound to Fe

IRE-BPs cannot bind to IRE RNA

62
Q

under low Fe conditions what is the relationship between IRE-BPs, Fe, and IRE RNA?

A

IRE-BPs not bound to Fe

IRE-BPs can bind to IRE RNA

63
Q

What happens to the level of transferrin receptor protein in low iron conditions?

A

protein level increases

64
Q

what happens to the level of transferrin receptor protein in high iron conditions?

A

protein level decreases

65
Q

what is the mechanism of transferrin receptor protein regulation?

A

in low iron situations, IRE-binding protein binds to IRE of mRNA protecting the mRNA strand from being degraded and thus synthesis continues (opposite in high iron situations)

66
Q

what happens to ferritin levels in low iron concentrations?

A

decrease

67
Q

what happens to ferritin levels in high iron concentrations?

A

increases

68
Q

what is mechanism of ferritin regulation?

A

in low iron situations, IRE-BP binds to IRE thus inhibiting ferritin synthesis because IRE prior to start codon (opposite in high concentration)

69
Q

what is cap-independent translation?

A

mRNA does not require cap to initiate synthesis, instead has internal ribosomal entry site (IRES) which can recruit the subunit

70
Q

why is cap-independent translation important for viruses?

A

because virus can shut down cap-dependent translation by cleaving eIF4G in the eukaryotic cell but continue replicating its own RNA

71
Q

how does mTOR regulate eIF4E?

A

mTOR can induce phosphorylation on the eIF4E-binding protein thus dissociating the binding protein from the initiating factor thus allowing translation to occur

72
Q

what is the process of interferon signaling?

A

cell infected by virus, infected cell creates interferons which signals other cells to create anti-viral measures (eIF2 kinase), virus cannot proliferate in cells notified by initial infected translation machinery shut off

M2M Biochemistry and molecular biology (19 decks)

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