A ribosome is an internal component of a biological cell (known as organelles) that is responsible in assembling molecules of specific amino acid to form a certain protein molecule, which will be determined by the nucleotide sequence of an RNA molecule.
Ribosomes are also called as the workbenches wherein proteins are manufactured. It is primary composed of several ribonucleic acid and proteins that reads messenger RNA and thus synthesizes proteins. All cells including archeabacteria have ribosomes. They are one of the numerous types of ribozymes, which are RNA molecules that catalyzes chemical reactions.
Free ribosomes freely float in the cytoplasm of the cell and the membrane-bound ribosomes bind to the nuclear membrane or to the endoplasmic reticulum. Ribosome function is vital for the production of proteins, or polypeptide chains, from the mRNA. They are composed of one or two very huge rRNA molecules and numerous smaller protein molecules. Proteins that are smaller act as building blocks in creating polypeptides using the rRNA as a scaffold.
The rRNA in ribosomes, for the eukaryotes, is organized into four strands, and three stands in prokaryotes. Eukaryote ribosomes are being produced and assembled in the nucleolus. Ribosomal proteins entering the nucleolus will combine with the four rRNA strands in order to produce the two ribosomal subunits, wherein one small and one large, that will make up the completed ribosome. The units of ribosomes will leave the nucleus via the nuclear pores and will unite once again in the cytoplasm for protein synthesis purposes. The two subunits of a ribosome are separated when the production of protein is not being carried out.
Since a ribosome is not just a single piece, scientists named the two pieces or subunits as 60-S for the large part and 40-S for the small part. When the cells is about to create protein, mRNA is then created in the nucleus. The mRNA will be sent to the ribosomes and into the cell. The two subunits will come together and combine with the mRNA when it is already time to make protein. The subunits will be locked onto the mRNA and protein synthesis will begin.
The ribosome structure model 60-S/ 40-S works only for the eukaryotic cell because prokaryotic cells have ribosomes made of 50-S and 30-S subunits. Scientists used the difference in the size of ribosome in the development of drugs that treat diseases caused by prokaryotic microorganisms.