ríbósómum

A ribosome is a complex molecular machine found within all living cells, responsible for protein synthesis. It is composed of ribonucleic acid (RNA) and proteins, and its primary function is to translate genetic information from messenger RNA (mRNA) into amino acid sequences, which ultimately form proteins. Ribosomes are essential for life, as proteins are crucial for the structure, function, and regulation of the body's tissues and organs.

Ribosomes are typically divided into two main types: cytoplasmic ribosomes, which are found in the cytoplasm of cells, and mitochondrial ribosomes, which are located within the mitochondria. Cytoplasmic ribosomes are further classified into two categories based on their location: free ribosomes, which float freely in the cytoplasm, and bound ribosomes, which are attached to the endoplasmic reticulum (ER).

The structure of a ribosome is complex and highly conserved across different species. It consists of two distinct subunits, often referred to as the large and small subunits. In eukaryotic cells, the small subunit is composed of a single RNA molecule and approximately 33 proteins, while the large subunit contains three RNA molecules and around 46 proteins. In prokaryotic cells, the numbers are slightly different, with the small subunit containing one RNA molecule and 21 proteins, and the large subunit containing two RNA molecules and 31 proteins.

The process of protein synthesis occurs in three main stages: initiation, elongation, and termination. During initiation, the small ribosomal subunit binds to the mRNA and the start codon, which signals the beginning of the protein sequence. The large subunit then joins the complex, and the process of elongation begins. During elongation, the ribosome reads the mRNA sequence in groups of three nucleotides, known as codons, and adds the corresponding amino acid to the growing protein chain. This process continues until the ribosome reaches a stop codon, which signals the end of the protein sequence. The ribosome then dissociates from the mRNA, and the newly synthesized protein is released into the cytoplasm.