IB Biology Topic B2.2.7 Structure and Function of…

Ribosomes: The Protein Synthesis Machinery

A ribosome is a complex of ribosomal RNA (rRNA) and proteins that catalyses translation, the synthesis of polypeptides from an mRNA template.
1. The small subunit binds mRNA and ensures correct codon-anticodon matching.
2. The large subunit catalyses peptide bond formation and provides an exit tunnel for the growing polypeptide chain.
Eukaryotic ribosomes are 80S (a 40S small subunit and a 60S large subunit), while prokaryotic ribosomes are 70S.
1. Ribosomes are not permanently free or bound: the same ribosome can be free in one round of translation and bound in the next.
2. What determines where it ends up is the protein it is making.

A ribosome is a complex of ribosomal RNA (rRNA) and proteins that catalyses translation, the synthesis of polypeptides from an mRNA template.
1. The small subunit binds mRNA and ensures correct codon-anticodon matching.
2. The large subunit catalyses peptide bond formation and provides an exit tunnel for the growing polypeptide chain.
Eukaryotic ribosomes are 80S (a 40S small subunit and a 60S large subunit), while prokaryotic ribosomes are 70S.
1. Ribosomes are not permanently free or bound: the same ribosome can be free in one round of translation and bound in the next.
2. What determines where it ends up is the protein it is making.