Translation Flashcards
What are codons
triplets of nucleotides
genetic code using codons is redundant
one codon = one protein
When do prokaryotes and euk translate
Pro = before transcription
Euk = transcriptio in nucleus, translation in cytoplasm
How is the order of amino acids during translation chosen
Specified by codons in mRNA
tRNA acts as adapter via anticodon-codon interaction, tRNA brings correct amino acid to mRNA codon
what is the tRNA called that attached specific amino acids to their tRNAs
aminoacyl-tRNA synthetases (enzymes)
tRNA charging (aminoacylation) process
Activation
1) Specific amino acidbinds to aminoacyl-tRNA synthetase enzyme
2) ATP activates amino acid to form aminoacyl-AMP
3) Pyrophosphte released as byproduct
Binding of tRNA
4) tRNA enters active site of aminoacyl-tRNA synthetase
5) Matches anticodon and amino acid of tRNA
tranfer
6) enzyme transfers activated amino acid to 3’ end of tRNA
7) AMP released as byproduct
Release charged tRNA
8) tRNA charged and released, ready for translation
what sites does the ribosome have that mRNA meets charged tRNA at
Aminoacyl-tRNA (A)
peptidyl-tRNA (P)
exit (E)
translation three phases
initiation
elongation
termination
Initiation process
initiation complex forms, consisting of the initiator tRNA charged with methionine and the small ribosomal subunit bound to mRNA triggers the beginning of translation
Elongation
Ribosome moves along one codon at a time in 5’ to 3’ direction
Polypeptides grow from N terminus to C terminus
Charged tRNA’s bring amino acids to ribosome
How is specificity provided during elongation
anticodon (tRNA) - codon (mRNA) interaction
accuracy of aminoacyl-tRNA synthetases
what are polysomes
clusters of multiple ribosomes attached to single mRNA strand, simultaneously translating it into protein
