Translation

Adjunto:

• Transcription

Nota:

• Correspondence between the nucleic acid and the polypeptide sequence. The group of bases a codon is necessary to specify a specific amino acid. Reading frames are the part where it is coded to the glycoproteins.

1. Properties

   Nota:

   • Genetic code is degenerate and non-random. It is read using the code table, it is non-random and the changes in the 3rd codon position signify the changes.

Nota:

• Adaptor molecules Similar structure  of 54- 100 nucleotides or around 74 Normally arranged in a cloverleaf strucutre. It has numerous post-transcriptionally modified bases.

1. Aminoacylation

   Nota:

   • Recognition step: Correct amino acid must be selected by aminoacyl-tRNA synthetase THe aa-trna is paired with a mRNA codon at ribosome. The 1st step where the amino acid binds to tRNA requires one ATP  to convert to AMP that is an activation step Aminoacyl-tRNA recogniser unique structural factors of tRNA and fidelity of the aminoacylation is enhanced by proof-reading.

1. Functions

   Nota:

   • Sites of protein synthesis Binds mRNA that codons can be read with High Fidelity. Specific binding sites for tRNA molecules. Mediates interaction of non-ribosomal protein factors that promote polypeptide chain initiation elongation and termination. Catalyses peptide bond formation.
2. Structure

   Nota:

   • Complexes of RNA and Proteins Comprises of a small subunit and a large subunit. aa-tRNA binds to A site peptiyldl-tRNA binds to P Deacylated tRNA binds to the E-site Subunits: 30s Subunit with 16s rRNA and 21 different different proteins 50s Subunit with 5s and 23s rRNA and 31 different proteins.

Nota:

• Forms in the nucleolus to be transported to the nucleus. Transcription and translation happens at the same time.

1. Structure

   Nota:

   • 2 subunits: Small 40s Subunit consisting of 18S rRNA with 33 different proteins Large 60 S subunit consisting of 5S, 8 S and 28S rRNA with 49 different proteins.
2. Overview

   Nota:

   • Polypeptide synthesis proceeds from N to C-terminus Chain elongation by linking the growing polypeptide to the incoming tRNA's amino acid Generate/Read mRNA in 5' to 3' direction Active translation only occur on polysomes.
   1. Polysomes
3. Peptide Bond Formation

   Nota:

   • A-sides moves on P site, then it then goes to E site to exit.
   1. Initiaition

      Nota:

      • AUG codes for start. But the pyrimidine-rich 3' end of 16s rRNA and purine sequence near the start codon. Shine-Delgarno Sequence to initiate translation HOWEVER not found in eukaryotes. THe tRNA that initiates FMet-tRNA. the 70S ribosome is opened up by IF-3, fMet-tRNA is bound ot the 30S initiation complex 50S then comes in and displace those things and cut it off.
      1. Elongation

         Nota:

         • 3 steps, decoding which uses one GTP, Transpeptidation, and translocation which uses another GTP
         1. Termination

            Nota:

            • Different stop codons hence there are different release factors. Empty A-sites was bound by RF-1 and GTP. GTP is bound with RF-3 and  it is dephosphorylated  to release 30S.

Nota:

• How to fold properly and cellular destination. Chaperones assist with folding process and the post translational processing that includes proteolysis, covalent modification and the translatcation thru membrane and glycosylation.