Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BCH311 > Translation > Flashcards

Translation Flashcards

(104 cards)

Start Studying
1
Q

Three sites present in ribosome

A

A site (aminoacyl)
P site (peptidyl)
E site (exit)

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

What does A site stand for?

A

aminoacyl

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

What does P site stand for

A

peptidyl

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

What does E site stand for?

A

exit

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

Function of small ribosomal subunit

A

interact with mRNA

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

Function of large ribosomal subunit

A

catalyze peptide bond formation

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

What are synonyms in genetic code?

A

codons specifying the same aa

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

Featurs of most synonyms

A

different in the last base of triplet

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

Who got the nobel prize for elucidating the genetic code?

A

R. Holley
G. Khorana
M. Nirenberg

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

How did ppl elucidate the genetic code?

A

first made UCC –> Phe,
then tested out other codons

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

how many stop codons are there?

A

3 (UAA, UAG, UGA)

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

Most synoyms present for one aa

A

6 for both serine and leucine

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

What enzymes are invovled in forming aminoacyl-tRNA from tRNA?

A

Aminoacyl-tRNA synthetase

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

least synoyms present for one aa

A

Met, Trp

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

What direction does polypeptide growth occur?

A

from N to C terminal

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

chemicals needed for aminoacyl-tRNA formation (generic sense)?

A

i) ATP (power source for reaction)
ii) Mg2+
iii) tRNA

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

Function of methylation in tRNA structure or function

A

i) prevent base pairing from happening
ii) provide hydrophobicity for interacting with synthetase

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

Structural features of tRNA

A

i) L-shaped
ii) CCA extend from one end of L-shape
iii) anticodon loop at the other end of L-shape
iv) bases in non-helical regions participate in H bond interactions

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

Which bases pariticipate in H bond interactions in tRNA?

A

non helical regions

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

What powers the formation of aminoacyl-tRNA?

A

ATP hydrolysis

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

Steps in synthesis of aminoacyl tRNA with class I synthetases

A

i) 2’OH of AMP on tRNA attack carboxyl group on aa
–> Class I aminoacyl tRNA synthetase
ii) AMP released, forming 2’O aminoacyl tRNA (aa linked to 2’OH of tRNA)
iii) carboxyl on aa attack 3’OH on tRNA
–>3’O aminoacyl tRNA

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

What happens in transesterification step for class I aminoacyl tRNA synthetase?

A

carboxyl group of aa attack 3’OH on tRNA
–> now aa connected to 3’OH of tRNA

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

Difference between class I and class II aminoacyl tRNA synthetase

A

i) only class I has transesterification rxn
ii) in class I, 1st nucleophilic attack from 2’OH of tRNA
in class II, 1st nucleophilic attack from 3’OH of tRNA
iii) Class I bind to front of tRNA, while class II binds to the side of tRNA
iv) Class I is monomeric, class II is dimeric

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

How much ATPs are needed for making one aminoacyl-tRNA?

A

one ATP for synthetase
one for regenerating AMP to ADP
(ATP +AMP –> 2 ADP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Similarities between class I and class II aminoacyl tRNA synthetase
i) AMP released ii) final product is 3'-O aminoacyl-tRNA iii) use nucleophilic attacks to connect aa to tRNA
26
nonmenclature for aminoacyl-tRNA synthetase
add certain aa to tRNA (e.g. Threonyl-tRNA synthetase)
27
Naming for aminoacyl tRNA
for alanine Alanyl-tRNA or tRNA^Ala
28
Naming for wrong aa incorporation into tRNA
e.g. serine added to tRNA for ala Y-tRNA^Ala or Serinyl-tRNA^Ala
29
What lower the chances of valine incorrectly incorporating into tRNA^Thr?
H bond forming between OH of Thr and Asp --> valine cannot form H bond with methyl grp
30
How does cells remove Serinyl-tRNA^Thr?
with help of aaRS, which recognizes it and hydrolyzes --> ignores Threonyl-tRNA^Thr
31
How does aminoacylation proofreading work?
it accepts smaller aa in editing site --> then hydrolyze them
32
How does tRNA move from synthetic domain to editing domain on synthetase?
similar to how DNA polymerase did --> without dissociation from synthetase, moving to editing domain
33
What does activation site (synthesis) of aminoacyl synthetase select for?
rejects large aa like Tyr and Phe, accepting activation sites
34
Unique feature of Thr-tRNA synthetase?
zinc that coordinates with Thr recognition
35
How does zinc interacts with theronine in Thr-tRNA synthetase?
amino grp and OH grp
36
important residues within Thr-aminoacyl synthetase that help with recognition
i) His *2 ii) Asp (interact with OH to form H bond) iii) Cys
37
How to identify nucleotides important for aminoacylation specificity in tRNA?
conducting mutation studies --> see if specificity constant (kcat//Km) is reduced--> efficiency of synthetase
38
important regions in tRNA^Asp for recongition by synthetase?
i) acceptor stem ii) anticodon (rlly important) iii) D loop
39
What region is used for recongition by alanyl-tRNA synthetase?
G:U at the microhelix region --> not including the anticodon region
40
Regions that are recognized by all tRNA synthetases?
nope anticodon not always recognized (e.g. in alanyl-tRNA synthetase)
41
What supported the finding of anticodon not needed for recognition of tRNA^Ala?
Did a mutation study on tRNA^Cys on 3:70 to G:U --> able to recognize as tRNA^Ala
42
Differences between binding configuration of class I and II tRNA synthetases?
Class I bind to the front Class II binds to the side
43
Crucial step before aa can be incorporated into the correct tRNA
aa is first adenylated
44
Structural differences between class I and II tRNA synthetases
class I: monomer class II: dimer
45
What are isoacceptor tRNAs?
diff. tRNAs that attach to the same aa --> tRNA with different anticodons but code for same aa
46
Difference between prokaryotic and eukaryotic ribosomes
i) size: prokaryote -- 70S, eukaryote -- 80S ii) more proteins attached to each subunit in eukaryotes iii) smaller subunit: 30S in pro, 40S in eu iv) larger subunit: 23S rRNA in pro, 5.8, 28S rRNA in eu
47
Where does ribosome function as polysome?
both prokaryotes and eukaryotes
48
What does prokaryotic ribsome recognizes?
Shine-dalgarno sequences
49
Which region recognizes the shine dalgarno sequence?
3' end of 16S rRNA
50
Features of shine dalgarno sequence
purine rich
51
Features for initial tRNA in prokaryotes targeting Met
i) has formyl grp attached
52
What helps with transformylation of methionyl-tRNAi ^ fMet?
Met-tRNA fMet i formyl transferase
53
What is prokaryotic ribosome made of?
50S and 30S subunit
54
Which site does the initiator tRNA in prokaryotes enter?
P site
55
Major steps in prokaryotic translation
i) initiator tRNA connected to Met enter P site, then another tRNA enters A site ii)peptide bond formed iii) translocation to next site is driven by GTP hydrolysis --> help from elongation factor G iv) tRNA at E site leaves ribosome
56
Function of elongation factor G
help catalyze translocation of mRNA and ribosome in prokaryotes
57
What determines the protein sequence?
mRNA sequence --> nothing to do with aa on tRNA
58
Who proposed the wobble hypothesis for codon:anticodon pairing?
Francis Crick
59
What base in anticodon can pair with the most codons?
Inosine --> U,C,A
60
what base can inosine pair with in codon?
U,C,A
61
What base in anticodon can pair with the least codons?
A,C --> can only do Watson crick pairing
62
Residues responsible for checking base pairing between codon and anticodon
A1493,A1492 G530 --> form H bond with them
63
Why only the third position in codon can do wobble pairing?
no residues in ribosome to check codon:anticodon pairing --> more flexibility
64
What happens if codon:anticodon pairing is wrong in first two positions of codon?
unable to form H bonds with residues --> leave the ribosome
65
Where does IF1 bind to?
near A site on 30S subunit in prokaryotes
66
Function of IF-3 in translation
prevents premature binding of 50S
67
Function of IF-2
associates with tRNAfMet --> GTP bound Stimulates association of 50S to complex
68
How does translation initiation occur in prokaryotes?
i) IF-3, IF-1 binds to 30S subunit, prevent 50S from binding ii) GTP bound- IF2 binds to initiator tRNA for Met iii) brings it to mRNA with shine dalgarno sequence iv) with GTP hydrolysis, IFs dissociates form complex and 50S binds
69
Function of IF-1
Direct IF-2 bound initiator tRNA to P site
70
What are the targets for EF-Tu?
any aminoacyl-tRNA with correct codon:anticodon pairing --> excluding fMet-tRNAf
71
Function of EF-Tu
i) protects ester linkage in tRNA from hydrolysis ii) bring aminoacyl tRNA to A site of ribosome
72
Why GTP hydrolysis is needed after EF-Tu binds aminoacyl tRNA?
as a confirmation for the correct codon:anticodon pairing
73
Function of EF-T
help regenerate EF-Tu that is bound to GTP, instead of GDP
74
How is EF-Tu regenerated?
i)EF-Tu with GDP is replaced with EF-T that removes GDP ii) GTP joins in and EF-T leaves EF-Tu
75
How does translocation occur in prokaryotes?
i) GTP bound EF-G bind to 50S ii) GTP hydrolysis lead to conformational change in EF-G iii) causes mRNA and tRNA to move by one codon iv) EF-G dissociates to allow ribosome to accept another aminoacyl tRNA
76
Where does EF-G bind to prokaryotes?
A site of 50S ribosome
77
Function of RF-3 in prokaryotes
mediate interaction between RF-1, RF02 and ribosome
78
What compounds have similar structure to EF-G with tRNA?
EF-Tu binding to aminoacyl tRNA
79
What recognizes stop codons?
release factors (RFs)
80
Function of RF-1 in prokaryotes
recognizes UAA, UAG
81
Function of RF-2 in prokaryotes
recognizes UAA, UGA
82
which RFs are GTP-bound?
RF-3
83
How does termination occur in prokaryotes?
i) Once stop codon is at A site, GTP-bound RF-3 with RF-1/2 binds at A site ii) H2O from RF led to hydrolysis of ester linkage in polypeptide chain iii) GTP hydrolysis of RF3 + GTP-RRF --> ribosomal complex dissociates
84
What proteins are GTP bound within prokaryotic translation?
IF2, EF-Tu, EF-G RF-3, RRF (ribosomal release factor)
85
What does eIF4E bind to?
methyl cap
86
Function of eIF2
similar to IF2, it binds to initiator tRNA and 60s ribosome
87
Steps for eukaryotic translation
i) eIF4E in eIF4F complex bind methyl cap ii) 43S ribosome complex (initiator tRNA, GTP-eIF2, 40S subunit) joins eIF4F complex iii) starts to scan for start codon (AUG) with help of ATP hydrolysis iv) 60S subunit joins in with eIF5B + all other eIFs dissociated v)80S ribosome complex formed
88
Function of eIF3
i) prevents 60S recruited in absence of initiation complex ii) promote initiator tRNA and mRNA binding
89
what binds to poly A tail?
PABP (poly A binding protein)
90
Translocation part of eukaryotes
i) instead of EF-Tu, EF1alpha brings in aminoacyl tRNA plus GTP to A site ii) EF1alpha is regenerated with help of EF1betagamma iii) mRNA and tRNA moves with help of EF2 (similar to EF-G)
91
Function of EF1alpha
brings in aminoacyl tRNA plus GTP to A site
92
Function of EF1betagamma
regenerates EF1alpha
93
Function of EF2
mRNA and tRNA moves by one codon
94
Termination of eukaryotes
carried out by one RF, which recognizes stop codon --> hydrolysis removes polypeptide chain from ribosome --->GTP hydrolysis lead to dissociation of ribosomal complex
95
How does puromycin interrupts with translation?
act as analog of aminoacyl tRNA --> lead to pre-mature termination
96
In what organisms is puromycin effective in?
prokaryotes and eukaryotes
97
Why does puromycin lead to pre-mature termination?
NH2 in puromycin attackes carboxyl grp in aa of P site --> forms a peptide bond + cannot carry out nucleophilic attack at 3'OH -- later dissociates
98
How does streptomycin interupts translation?
inhibits intiation in prokaryotes with the highly basic properties
99
In what organisms is streptomycin effective in?
prokaryotes
100
Function of B fragment in diptheria toxin
allow A to enter cytoplasm of cells
101
Function of A fragment in diptheria toxin
catalyze covalent modifications
102
How does diptheria toxin stops translation?
i) first cleaved into A and B after entry ii) A catalyzes covalent modification with NAD+ iii)this blocks EF2 function, stops protein synthesis
103
How does ricin stop translation?
A chai removes a conserved residue (A4324) in 28SrRNA --> doesn't allow EF to bind
103
configuration of ricin
heterodimeric A and B --> A is catalyic

BCH311 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions