Dna translation

DNA TRANSLATION

DNA

RNA

Protein

Transcription

Translation

CENTRAL DOGMA

Key molecules of translation

mRNA

Ribosomes

tRNA

Release factor


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)


tRNA(Transfer RNA)

Attachment between Anticodon of tRNA and codon of target gene :-necessary step in 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


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


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 .


TERMINATIONIncludes 7 steps


THANK YOU -Anjali shah

Science

Dna translation