ribosomes

Ribosomes are microscopic cellular structures responsible for protein synthesis in all living organisms. Composed of ribosomal RNA (rRNA) and proteins, ribosomes serve as the site where genetic information encoded in messenger RNA (mRNA) is translated into amino acid sequences to form proteins. They are found in both prokaryotic and eukaryotic cells, either free-floating within the cytoplasm or attached to the endoplasmic reticulum in eukaryotes, known as rough endoplasmic reticulum.

Structurally, ribosomes consist of two subunits: a small subunit that binds to the mRNA and a large subunit that facilitates the formation of peptide bonds between amino acids. The size of ribosomal subunits is measured in Svedberg units (S), with prokaryotic ribosomes being 70S and eukaryotic ribosomes being 80S.

The process of protein synthesis begins when the small ribosomal subunit attaches to the mRNA. Transfer RNA (tRNA) molecules then deliver specific amino acids to the ribosome, where they are assembled into polypeptides based on the sequence dictated by the mRNA. This process, called translation, involves initiation, elongation, and termination phases.

Ribosomes are vital for cellular function and growth, facilitating the expression of genes into functional proteins necessary for structural, enzymatic, and regulatory roles. Their high conservation across species highlights their fundamental importance in biology. Advances in microscopy and molecular biology have enhanced understanding of ribosome structure and function, contributing to fields such as genetics, medicine, and biotechnology.