Ribosomes


In the biological context, ribosomes are small fractions of molecules where the process of protein synthesis originates. These particles can only be seen through an electron microscope. The first to discover ribosomes was the cell biology specialist George Palade, this happened in 1953, being defined at that time as minute and very abundant globular structures within the cytoplasm of the cell.

Ribosomes originate inside the cell nucleus, and then move to the cytoplasm, where they perform different functions, which will be subject to the cell to which they belong.

As already mentioned, ribosomes have an extremely tiny size, so in order to be observed, it is necessary to use a microscope. their dimension will depend on the cell to which they belong, for example in eukaryotic cells, the ribosome will have a diameter of 320 Angstrom. While in prokaryotes, its size is reduced to 290 Angstrom.

Ribosomes can be distributed in isolation within the cell, or on the contrary they can form polyribosomes. the truth is that they can be found attached to the endoplasmic reticulum or near the cell membrane.

Its main function is to synthesize proteins, this process is known as “translation”. Through this process, the message included in the nuclear DNA and that had previously been reproduced in a messenger RNA is translated in the cytoplasm, together with the ribosomes and the transfer RNAs that transport the amino acids, for the production of cellular proteins. and secretion.

Two classes of ribosomes can be differentiated, depending on their sedimentation coefficient: 70S ribosomes and 80S ribosomes.

Ribosomes are structured by two subunits of different dimensions and varying sedimentation coefficients. One of them represents the large subunit and the other, the small subunit.

On the other hand, it is important to differentiate between polysomes and ribosomes. Polysomes represent a chain of ribosomes linked by a 2mm thick cord or fiber. Another difference that can be observed between them is in their function; ribosomes synthesize export proteins, while polysomes synthesize cellular location proteins.