Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MOLBIO > PHILLIPS CH11 > Flashcards

PHILLIPS CH11 Flashcards

1
Q

anticodon

A

on tRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

codon

A

on mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

aminoacyl-tRNA synthetase

A

attach amino acids to tRNA (require ATP)
recognize both AA and rRNA, one for each AA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

2 subunits of ribosomes

A

small subunit deciphers mRNA
large subunit mediates chemical bond formations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

rate of protein synthesis

A

15 AAs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

translation factors

A

often GTPases, associate with ribosomes and help with translation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

4 regions of tRNA structure

A

acceptor stem and 3 stem-loops (D-loop, T-loop, anticodon loop)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

D-loop

A

contains dihydrouridine (D)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

T-loop

A

contains ribothymidine (T) and pseudouridine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

anticodon loop

A

contains a hypermodified purine (H) after the anticodon to prevent this from base-pairing with mRNA codon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

acceptor stem

A

5’ and 3’ ends base pair, 3’ CCA tail binds the AA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

draw structures of dihydrouridine, pseudouridine, inosine

A

see notes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

discovery of triplet code

A

three insertions or three deletions restores function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

number of codons

A

61 sense codons (AA)
3 antisense codons (stop/nonsense - end of protein)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

wobble pairing

A

non Watson-Crick base pairing
can occur on the third position of codon
(e.g. UUC and UUU can pair with AAG)
each codon does not need own tRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

isoacceptors

A

different tRNAs that carry the same amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

how do aminoacyl-tRNA synthetases recognize tRNAs?

A

by sequence and structural features called identity elements, often found n anticodon loop or acceptor stem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

EFTu

A

protect highly-reactive aminoacyl-tRNAs and deliver to ribosome A site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

size exclusion

A

keeps non-cognate AAs that are too big out of the aminoacylation site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

editing site

A

site on aminoacyl-tRNA synthetase that accomodates similar or smaller non-cognate AAs to prevent errors in aminoacylation
pre- or post- transfer
(essentially gives another site for wrong AAs to go)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

process of aminoacyl-tRNA synthetase adding a correct AA

A

via ATP, AA enters aminoacylation site, tRNA attaches to it, AA cannot enter the editing site, remains attached to tRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

16S rRNA

A

mediates interaction between tRNA and mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

23S rRNA

A

found in peptidyl transferase center, interacts with tRNAs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

3 binding sites in ribosomes for tRNAs

A

A: aminoacyl site
P: peptidyl site
E: exit site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

initiation (translation in bacteria)

A

initiation factors load initiator methionine tRNA into the P site of the small subunit and the large subunit joins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

elongation (translation in bacteria)

A

1) elongation factor Tu loads next aminoacyl tRNA into A site of ribosome
2) ribosomal peptidyl transferase catalyzes peptide bond formation
3) elongation factor G (EFG) promotes movement of the mRNA - tRNA complex places next codon into A site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

termination (translation in bacteria)

A

class I release factors recognize the stop codon, tRNA releases polypeptide chain, recycling factors promote dissociation of ribosomal subunits from one another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

ribosome recycling

A

dissociation of ribosomal subunits and release of tRNA and mRNA

29
Q

polysomes

A

many ribosomes piled up on the same mRNA (elongates simultaneously)
transcription and translation occur simultaneously only in bacteria

30
Q

GTPases

A

catalyze the hydrolysis of GTP to GDP
EFTu, eIF2, EFG

31
Q

EFTu

A

protects and delivers aminoacyl-tRNA to ribosome A site

32
Q

eIF2

A

loads tRNA methionine into P site during initiation

33
Q

EFG

A

promotes directional movement of mRNA-tRNA complex through ribosome
binds in A site

34
Q

GAPs

A

GTPase activating proteins, promote GTP hydrolysis

35
Q

GEFs

A

guanine-nucleotide exchange factors, promote exchange of GDP to GTP

36
Q

initiator tRNA

A

distinct from tRNA(met), structure prevents binding by elongation factors

tRNA(fMet) in bacteria, tRNAi(Met) in eukaryotes

37
Q

polycistronic

A

having several open reading frames, each frame has its own start and stop codon (e.g. bacterial mRNAs)

38
Q

Shine-Dalgarno sequence

A

polypurine tract 6-8 bases upstream of initiator AUG, usually in initiation codons

39
Q

anti-Shine-Dalgarno sequence

A

polypyrimidine region in the 3’ end of the bacterial 16S rRNA, pairs with Shine-Dalgarno sequence

pairing guides initiator AUG mRNA into P site

40
Q

initiation factors that guide tRNA(fMet)

A

IF1, IF2, IF3

41
Q

IF1 and IF3

A

binds the A and E sites (respectively) of the small ribosomal subunit in the absence of mRNA or tRNA(fMet)

direct the initiator tRNA to P side, stops large ribosomal subunit from binding inappropriately

42
Q

monocistronic

A

mRNA only encoding one protein, eukaryotes

43
Q

AUG recognition in eukaryotes

A

scanning mechanism for first AUG
sensitive to sequence context - kozak sequence

44
Q

kozak sequence

A

consensus sequence containing AUG, dictates initiation efficiency

45
Q

eIF4E

A

binds eukaryotic mRNA 5’ cap

46
Q

PABP

A

binds eukaryotic mRNA 3’ poly A tail

47
Q

closed loop complex / elF4 complex

A

eukaryotic mRNA bound by elF4E (on 5’ cap) and PABP (3’ poly A tail) forms the closed loop, functions as quality control to weed out unfinished/damaged mRNAs

48
Q

pre-initiation complex (translation)

A

40S ribosomal subunit bound to initiation factors, primed to scan mRNA
initiator tRNAi(Met) bound to eIF2

49
Q

eIF5

A

stimulates GTP hydrolysis on eIF2

50
Q

initiation (translation in eukaryotes)

A

pre-initiation complex brought to closed loop complex, scans mRNA for AUG

51
Q

eIF4G

A

brings pre-initiation complex to the closed mRNA loop

52
Q

elongation (in bacteria and eukaryotes)

A

decoding, peptide bond formation, translocation, tRNA in E site leaves

53
Q

decoding

A

EFTu loads next charged tRNA into A site

cognate, near-cognate, non-cognate matches
cognate matches bind strongly with ribosome, stimulates conformational change in ribosome and aminoacyl-tRNA is released to A site

54
Q

peptide bond formation

A

catalyzed between the amino acid in the P site and A site

55
Q

translocation

A

mRNA-tRNA through ribosome move the peptidyl-tRNA from A to P site

56
Q

elF4E

A

binds 5’ cap, required to form the closed loop complex

57
Q

hybrid states model

A

in translocation, tRNAs first move independently, then anti-codon end moves (classic > rotated > classic)

58
Q

class I release factors

A

recognize stop codons in termination
RF1: recognizes UAA and UAG
RF2: recognizes UAA and UGA

59
Q

RRF

A

ribosome recycling factor

along with the EFG, acts as a wedge between ribosomal subunits > ribosome disassembly

60
Q

recoding

A

the genetic code is superseded and an mRNA is read differently than expected

61
Q

nonsense suppression

A

stop codons are misread and termination fails to occur

62
Q

peptidyl transferase

A

catalyzes peptide bond formation in growing polypeptide

63
Q

frameshifting

A

the mRNA shifts so the peptide synthesis proceeds in a different reading frame
ribosome moves by a number that is not 3, usually +1 or -1

64
Q

selenocysteine

A

“21st AA,” similar to cysteine but has selenium instead of sulfur, needed in the catalytic site of some enzymes

65
Q

how is selenocysteine loaded?

A

selenocystein-tRNA matches UGA stop codon, specialized loading protein SelB delivers it (can only deliver when there is a specific hairpin element in RNA)

66
Q

pyrrolysine

A

modified lysine, found in methyltransferase genes at catalytic sites

67
Q

how is pyrrolysine loaded?

A

it has its own aminoacyl-tRNA synthetase and tRNA which recognizes UAG stop codon, EFTu helps load

68
Q

programmed frameshifting of RF2 (termination factor)

A

high RF2: recognizes stop codon
low RF2: +1 frameshift so translation continues to produce RF2

MOLBIO (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions