DNA TRANSLATION
DNA
RNA
Protein
Transcription
Translation
CENTRAL DOGMA
Key molecules of translation
mRNA
Ribosomes
tRNA
Release factor
Key molecules of translation
mRNA(messenger RNA)
Product of transcription
• Convey genetic information from DNA to ribosome.
• Genetic information in the form of nucleotide.
• Three bases for each codon :- amino acids.
• It contain codon to which anticodon of tRNA get attached during translation.
Pre-mRNA
Matured mRNA
Nucleus
Transport to cytoplasm for protein synthesis (Translation)
Key molecules of translation
tRNA(Transfer RNA)
Attachment between Anticodon of tRNA and codon of target gene :-necessary step in translation
Key molecules of translation
Ribosomes
Baterial : 30s + 50s Mammalian : 40s +60s
Composed of rRNA and ribosomal protein
Present in both eukaryotes and prokaryotes
Model showing binding sites on ribosome assembly
Key molecules of translation
Release factor(eRF) Recognize all the 3 stop codons.
Bind to ribosome at site A. Stops protein biosynthesis and
release of the nascent polypeptide chain.
Same process in prokaryotes and eukaryotes
3 separate release factors exist, RF1, RF and RF3.
• Ribosomal assembly around target mRNA • First tRNA recognize and attach at start
codonInitiation• Attachment of second tRNA to target mRNA• Transfer of a.a. from first to second tRNAElongation• Translocation of ribosome to next mRNA
codon.• Formation of Amino acid chain.
Translocation
• Attachment of release factor at stop codon.• Release of polypeptide from ribosomeTermination
Phases of Translation
Initiationincludes
GTP (guanosineTriphosphat
e).
Initiation factors (IF)
Specific initiator tRNA
mRNA
Ribosome
INITIATION
Step for Initiation of Translation.
Interaction b/w small ribosomal subunit and IF-1 & IF-3.
Recognition of AUG(start) codon on mRNA.
Binding of mRNA on small subunit.
Recognition of RBS, upstream to AUG & IF-3 binding.
IF-3 prevents attachment of large subunit
ribosome-binding site(RBS)
Binding of a special initiator tRNA to the AUG start codon.
1st tRNA (tRNA.fMet) binding to small subunit.
methionyl–tRNA synthetase catalyzes the addition of methionine to the tRNA.
Enzyme transformylase adds the formyl group to the methionine.
Dissociation of all the three IF factors.Binding of large subunit by using energy.Energy : GTP hydrolysis to GDP
Russell igenetics molrcular approach
Binding of Aminoacyl–tRNA (charged tRNA)
Formation of peptide bonds
Translocation
ELONGATION AND TRANSLOCATION
Step for Elongation of Translation.
Binding of Aminoacyl–tRNA (charged tRNA) to A site of ribosome.
Formation of peptide bonds
Russell igenetics molrcular approach
Translocation ribosome and release of tRNA for next cycle.
Charging of tRNA
TERMINATION
Stop codon (UAG, UAA, and UGA) gives signals for termination of translationRelease factor recognize stop codon & bind to ribosomes.
Terminates translation with release of polypeptide chain .
Russell igenetics molrcular approach
TERMINATIONIncludes 7 steps
Russell igenetics molrcular approach
THANK YOU -Anjali shah