Translation Flashcards
mRNA’a are decoded in the 5’ to 3’ direction, ____ codon at a time
one
tRNA’s are _______ molecules with a common architecture which allow codon recognition and link _____ codons to specific ___________
adaptor, specific, amino acids
________ _____ _____ allows some tRNA’s to recognize alternative codons
wobble base pairing
linking an ____ ____ to a tRNA molecule requires specific _________ capable of reading the genetic code.
amino acid, enzymes
the ______ is the molecular machine in charge of protein synthesis
ribosome
the ______ polypeptide is the synthezied N term first
nascent
the ribosome is ____ subunits joined together around _____ to make an active site.
two, mRNA
tRNAs are a genetic ________ which assist in translation
dictionary
mRNA is read ____ to ____
5’, 3’
the core structure of the ribosome is formed by ________ _____.
ribosomal RNA
peptidyl transferase center is in the ______ between the _______ of the ribosome.
cleft , subunits
ribosomal proteins are on the surface but extend _____ into core rRNA structure to ________.
fingers, stabilize
the mature mRNA contains the sequence of the ______ in genetic code
protein
mRNA’s are decoded __ to __ direction in sets of ______ nonoverlapping nucleotides
5’, 3’, 3
translation begins at an initiator _____ codon. (MET)
AUG
frame shifting during translation is _______
rare
tRNAs contain the _______ for the mRNA and are linked to the cognate _____ ______ at the acceptor stem
anticodon, amino acid
anticodon loop basepairs with the _______
codon
the amino acid is added to the 3’ _______ sequence - CCA
adaptor
the nascent polypeptide chain the _____ terminus is made first and the __ terminus stays attached to the last tRNA. the chain emerges through ribosome _____ ______ which can protect 40 AA.
N, C, exit tunnel
in peptidyl transferase rxn, the ____ attacks ester linkage of adajacent tRNA, activated peptidyl tRNA bond is maintained
amine
protein folding and chaperone binding begins immediately upon emergance from ______ ______ _______
ribosome exit tunnel
why is translation complicated when the peptide bond is a simple chemical reaction?
you aren’t making any peptide bond but the CORRECT peptide bond; information transfer with speed and high fidelity. so cells expend a lot of energy to get it correct.
translational fidelity
- correct charging of ______ by tRNA synthetases
-codon dictated selection of matching ______ at the ribosome
-speed
tRNAS, tRNA
mechansims of translational fidelity
-tRNA synthetases
-degeneracy of _____ + wobble position
- monitoring of codon-anticodon _____
-________ coupling to irreversible hydrolysis steps- amplify signal of correct pairing
-kinetic proofreading
-ribosome quality control
code, basepairing, allosteric
aminoacyl tRNA synthetases ____ the genetic code and ______ the right amino acid with the right tRNA
read, couple
aminoacyl transferases perform ___ step coupling of AA to tRNAs. first is AA ______ then AA ______
two, activation, transfer
amino acids are couple to tRNA’s via high energy ______ bonds to the ______ of the ribose on the 3’ adenosine
ester, 3’OH
aminoacyl tRNA synthetases are highly ________ for their _______ and ______
specific, tRNA, amino acid
error rate on tRNA selection is better than AA selection, why?
because there is a larger surface are meaning more bond discrimination
double sieve mechanism is to ensure correct selection of _______ _______-
amino acid
at active site, mostly correct amino acids are ______
charged
at editing site, wrong amino acids are ______
removed
degeneracy of genetic code contributes to robustness of information _______-
transfer
like amino acids are encoded by like _______
codons
mutations do not always lead to changes in _______ ______ level
amino acid
wobble base pairing allows a single tRNA to recognize _______ codons
alternative
inosine is a modified base with ______ base pairing capabilities
broader
Inosine (I) can base pair with __, ___, ___.
C, U, A
the small ribosome subunit _____ ________
binds mRNA
the large ribosome subunit _______ the _______ ________ reaction
catalyzes, peptidyl transferase
tRNA’s bind in three sites, _________ , _________, ______
aminoacyl, peptidyl, exit (APE)
__________ proceeds in steps: tRNA ______, peptide bond _______, large+small subunit translation.
elongation, binding, formation
________ _____ around codon-anticodon basepairing of the first two bases in a codon ensures fidelity
induced fit
hydrolysis of GTP by two elongation factors EF-Tu, EF-G ensures ________ accuracy
translation
peptide bond formation is catalyzed by the peptidyl transferase ________ of the ribosome. catalysis by proximity and orientation. the energy for the reaction comes from reactivity of the high energy ester bond between ______ and ________.
center, tRNA, amino acid
mRNA molecules are translated in cycles of _____ steps
four
mRNA translation
1) tRNA binding at ___ site
2) peptide bond ______
3) ______ subunit translocated to ___ site
4) ______ subunit translocated to ___ site
5) ____ is ejected at ___ site
6) newly bound charge ____ binds at ___ site
A
formation
large, P
small, P
tRNA, E
tRNA, A
tRNA’s bind to the ribosome in a ternary complex with _____ and ______
EF-Tu, GTP
correct basepairing of tRNA trigger release of ______
GDP
incorrect basepared tRNA’s preferentially _______-
disassociate
correct codon-anticodon basepairing causes a __________ change that triggers GTP _______ in EF-Tu and disassociation
conformational, hydrolysis
EF-Tu disassociation begins accommodation which is the postioning of AA next to each other in peptidyl transferase site. this will take _______ for incorrect bp matches and allows more time for __________
longer, disassociation
induced fit is folding around _____ ______ that favors catalysis
base pair
kinetic proofreading is an ________ step that happens faster for _______ basepairs, making _______ basepairs have more time to disassociate
irreversible, correct, incorrect
GTP hydrolysis results in conformation changes in EF-G that force tRNA’s and mRNA to move through the ribsome by a distance of ______ codon
one
translocation of mRNA’s and tRNA’s through the ribosome is driven _______ by GTP _______-
forward, hydrolysis
______ _______ are bound by protein release factors (not tRNA’s)
stop codons
release factors force _______ which release the peptide then causing disassociation of the ribosome
hydrolysis
the same ______ can be translated by ________ ribosomes: polyribosomes
mRNA, multiple
problems in translation lead to ribosome _________
stalling
stalling can trigger pathways for
______ and _______ degradation
________ recycling
stress ______
mRNA, protein, ribosome, response
ribosome quality control is the research of identifying factors that recognize _________ ribosomes
stalled
