1. Initiation Translation
To begin translation: large and small ribosomal subunit, along with the initiating tRNA, assembles onto the mRNA 2. Translation Elongation
The next amino acyl-tRNA enters the ribosome at the A site
The amino acid at the P site is transferred to the tRNA at the A site. The ribosome moves one codon farther along the mRNA, releasing the empty tRNA through the E (exit) site. The A site is free for the next incoming RNA.
The cycle is repeated as the ribosome travels along the mRNA, resulting a growing polypeptide chain. 3. Termination
- is triggered by a stop codon (recognized by release factors which help release the fully synthesized polypeptide chain from the ribosome) - the ribosome separates from the mRNA
The first amino acid is always the same: AUG, Met.
Entire Translation Process
oIn translation, the sequence of bases in the mRNA is converted to an amino acid sequence in a protein oEach amino acid is specified by three bases (a codon) in the mRNA, according to a nearly universal genetic code oRibosomes catalyze translation of the mRNA sequence into protein oinside the ribosomes, mRNA are translated to proteins via intermediary molecules - tRNA otRNA carry an amino acid and have three-base-pair anti-codon, which binds to an mRNA codon. othe amino acid carried by the tRNA is then added to the growing protein via formation of peptide bond Moving down to the mRNA
occurs when the ribosome moves down the mRNA in the 5' - 3' direction, moves the empty tRNA into the E site, moves the tRNA containing the growing polypeptide into the P site, and opens the A site to expose a new mRNA codon The three steps in elongation repeat down the length of the mRNA 1.entrance of amino acid containing tRNA
2.peptide bond formation
Lecture #16 October 12/2012
- 1st step of translation: begins when a large and small ribosomal subunit, along with the initiating...