Ribosome

Ribosomes transcribe RNA into proteins during peptide encoding.

Length Scale

Length scales of the ribosome are quite tiny. Recall:

• An individual amino acid is on the order of $10^{-10}m$ - a couple of angstroms.
• A 30-amino-acid peptide is on the order of $10^{-8}m$
• The size of the mRNA for the protein is significantly smaller than the protein itself.
• The ribosome has two parts: one that reads the mRNA, and one that attaches an amino acid to the growing peptide chain.

The scales are so small that special equipment is needed to determine the ribosome shape/function.

Cartoon

From: Protein Data Bank, Molecule of the month #121

The green part of the cartoon handles the mRNA, and the blue part of the cartoon handles the tRNA.

Translation Process

By Boumphreyfr vector conversion by Glrx - File:Peptide syn.png, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=101457889

For each mRNA codon (nucleobase triplet), the ribosome attaches the corresponding tRNA, building the peptide chain with the tRNA amino acid. The protein databank provides the molecular process of the codon-anticodon binding here.

Translation Animation

The ribosome ratchets mRNA, attaching tRNA based on the anti-codon. From: DNAinteractive: http://www.dnai.org

The ribosome processes approximately 10 amino acids per second. If a typical protein is 300 amino acids, then it takes about 30s to translate it.