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GSBS Biochem > DNA 5 > Flashcards

DNA 5 Flashcards

1
Q

protein synthesis occurs at the

A

ribosome

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2
Q

the ribosome is a

A

complex formed of rRNA and several proteins

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3
Q

what must the ribosome hold to make a polypeptide

A

mRNA and tRNA

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4
Q

the details of the molecular recognition are key to making translation

A

probable

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5
Q

recognition of tRNA happens at

A

the decoding site
A site

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6
Q

catalysis happens at the

A

transferase center
p site

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7
Q

last spot of translation complex

A

exit
e site

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8
Q

ribosome total weight

A

70s

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9
Q

two segments of ribosome

A

30S and 50S

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10
Q

the 50S subunit contains

A

23S RNA
5S RNA
34 proteins

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11
Q

the 30S subunit contains

A

16S RNA
21 proteins

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12
Q

rRNA in the 90’s

A

shown with 50 A by electron microscopy

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13
Q

the secondary structure of such large RNAs can be

A

elaborate

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14
Q

which subunits are on the top and bottom

A

30S bottom
50S top

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15
Q

the 30S subunit holds

A

the mRNA

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16
Q

the 50S subunit catalyzes

A

the peptide bond formation

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17
Q

translocation and successive binding of the next tRNA are

A

GTP dependent

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18
Q

three sites for tRNA binding

A

A
P
E

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19
Q

as the peptide is made it can either

A

coil into an alpha helix or wait to be picked up by a chaperonin

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20
Q

the release factor signals

A

the end of the protein synthesis

21
Q

first the individual subunits must recognize and

A

bind

22
Q

release of the complex follows the stop codon and completion. this allows for

A

ribosome recycling and energy conservation

23
Q

to initiate complexation the tRNA must be… with its correct amino acids

A

charged

24
Q

tRNA is charged with

A

a tRNA synthetase

25
Q

tRNA synthetases are specific to

A

each amino acid which provides a level of proof reading

26
Q

after charging of a tRNA what can occur?

A

formylation

27
Q

first amino acid added

A

formyl methionine

28
Q

formyl methionine initiates

A

complex formation and starts the chain growth

29
Q

the usual lactam condensation is catalyzed at

A

the active site of the ribosome
the peptidyl transferase site

30
Q

when were the first 3 sites shown on EM work

A

1999 at 7.5 A
shows the three sites from the 30S and 50S POV

31
Q

the tRNA must fit in a specific pocket of the

A

70S complex

32
Q

the ribosome atomic structure was solved by

A

x-ray diffraction on 2000 to 2.7 A

33
Q

each of the 30S and 50S subunits have an interesting set of

A

domain structure

34
Q

the domain structures are specialized for

A

holding and release of tRNA

35
Q

how many proteins are in the ribosome in prokaryotes

A

55

36
Q

how many proteins are in the ribosome in eukaryotes

A

79-80

37
Q

proteins in the ribosome are

A

highly conserved across life forms and require chaperones

38
Q

how many subunits are conserved between life forms

A

15

38
Q

absense of some subunits in lower life forms shows evolutionary additions usually on the

A

outside

39
Q

the proteins in the ribosome have different tertiary structures than

A

globular proteins

40
Q

proteins in the ribosome have long strands that reach deeply into the rRNA making

A

favorable contacts

41
Q

there are no proteins in

A

the peptidyl transferase center

42
Q

the ribosome is a

A

ribozyme

43
Q

under stress conditions such as heat or antibiotics

A

ribosomes stall leading to halted protein synthesis

44
Q

to remobilize ribosomes bacteria use

A

rescue factors such as HflXr, a GTPase, that catalyzes the dissociation of translational inactive ribosomes into individual subunits

45
Q

bacterial chromosomes spend a considerable amount of time in an inactive state known as

A

ribosome hibernation

46
Q

during ribosome hibernation

A

the subunits dissociate and bind protein hibernation factors

47
Q

some hibernation factors occupy

A

drug binding sites, antibiotics and recycling affect each other

GSBS Biochem (10 decks)

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