Translation Flashcards
Translation
Synthesis of a polypeptide specified by an mRNA
Codon
A triplet of bases that code for 1 amino acid
Starting point
Sets the reading frame
Characteristics of the genetic code
Universal, non-overlapping, degenerate
Degenerate
More than one codon can code for the same amino acid
Nonsense mutation
Introduces a stop codon which produces an incomplete polypeptide
Frameshift mutations
Deletes or inserts a base which changes the whole amino acid sequence
Transition point mutation
Substituting a purine/pyrimidine for another purine/pyrimidine
Transversion point mutation
Substituting a purine for a pyrimidine or vice versa
Transfer RNA
Has a stem-loop structure, it is made up of an acceptor stem, D loop, anticodon loop, variable loop and Tc loop
Acceptor stem
Site of aminoacylation
D loop
Contains the modified base dihydrouridine which stabilizes the tRNA structure
Anticodon loop
Recognizes codon on mRNA
Variable loop
It varies in size and structure, and its not always present
T¥C loop
Recognition site for enzymes for protein synthesis
Ribosome structure
Made up of r RNA and peptides, and consists of the A site, P site and E site
A site
Binds incoming aminoacyl-tRNA
P site
Binds peptidyl tRNA
E site
Exit site for uncharged tRNA
Sedimentation coefficient (s)
Measures particle’s size by sedimentation rate
N-formylated Met
A formyl group added to a methionine , its tRNA initiates translation since it is the one that is recognized by the start codon
Shine- dalgarno sequence
A purine rich tract in mRNA that helps recruit the ribosome to the start codon, only found in prokaryotes
Initiation factors
Proteins that bind to the small ribosomal unit
Initiation
Inactive ribosomes are dissociated
mRNA, fMet-tRNA, GTP, IFs bind to 30S
GTP releases a phosphate
50S and 30S join, fMet-tRNA enters P site and A site is ready to accept AA-tRNA
Elongation
Uses elongation factors and is done in the steps, AA-tRNA binding, transpeptidation, translocation, and termination
AA-tRNA binding
It binds to the A site and GTP becomes GDP
Transpeptidation
Formation of a peptide bond by peptidyl transferase so that the peptidyl can be transferred to the AA-tRNA
Translocation
Previous peptidyl-tRNA moves to E site to get released and the new one moves to the P site
Termination
Release factors recognize stop codons, this causes peptidyl transferase to transfer the peptidyl group to water.
Release of phosphate by GTP causes the release of the RFs and inactivates the ribosomes
Chloramphenicol
Inhibits peptidyl transferase on prokaryotic large subunit
Cycloheximide
Inhibits peptidyl transferase on eukaryotic large subunit
Erythromycin
Inhibits prokaryotic translocation
Tetracycline
Inhibits binding of AA-tRNA to prokaryotic small subunit
Diphtheria toxin
Catalytically inactivates eEF-2
