Discovery of Ribosomes and Their Role in Protein Synthesis

The combination of cell fractionation and electron microscopy revolutionized biology, allowing scientists to visualize and understand cellular structures. In 1930, Albert Claude at Rockefeller University developed cell fractionation, a process that grinds and centrifuges cells to separate their components based on weight.

His student, George Palade, refined this technique in 1955 and used an electron microscope to examine the separated cell components. In 1958, Palade identified and named ribosomes, the granular structures responsible for protein synthesis. Both Claude and Palade were awarded the 1974 Nobel Prize for their contributions.

Ribosomes: The Cell’s Protein Factories

Ribosomes are universal organelles found in all living organisms, acting as protein synthesis factories. Their function involves:

1. DNA encoding instructions for protein synthesis.
2. mRNA (messenger RNA) carrying these instructions to the ribosome.
3. tRNA (transfer RNA) bringing amino acids to build proteins.

Cells with high protein synthesis rates (like those in the pancreas) contain millions of ribosomes.

Eukaryotic vs. Prokaryotic Ribosomes

• In eukaryotic cells (animals, plants, fungi), ribosomes are attached to rough endoplasmic reticulum.
• In prokaryotic cells (bacteria), they float freely in the cytosol.
• Despite differences in density and structure, their function remains the same.

Medical Significance of Ribosomal Differences

Palade discovered structural variations between bacterial (prokaryotic) and human (eukaryotic) ribosomes, which is crucial for medicine. Antibiotics like erythromycin and tetracyclines exploit these differences by targeting bacterial ribosomes while leaving human ribosomes unaffected, making them effective treatments for bacterial infections.

The primary function of ribosomes is the manufacture of proteins. The image depicts a model of a eukaryotic ribosome, which differs in structure from a prokaryotic ribosome.