Ribosomes are the organelles found in both the prokaryotic and eukaryotic cells, that are responsible for the synthesis of the proteins. Chemically they are made up of RNA and proteins, that’s why they are also known as ribonucleoproteins. These organelles are synthesized in the nucleolus inside the nucleus. It has two subunits the large ribosomal subunit(the 60S) and the small ribosomal subunit(40S). Once they are synthesized, they are exported out of the nucleus through the nuclear pores into the cytoplasm, where they attach to the endoplasmic reticulum or are randomly scattered in the cytoplasm.
Ribosomes are the machinery for one of the important steps of the central dogma i.e. translation. Once the information has been transcribed from the DNA into the mRNA, it is further processed by the ribosomes to translate the information inside the mRNA into the polypeptide chains. The mRNA has specific codons that code for different and specific amino acids. The two subunits of the ribosome attach to the mRNA sequence, reading the codon and specific tRNA with the anticodon binding onto the mRNA sequence on the ribosome. The tRNA exists as an aminoacyl tRNA complex, which means that each anticodon tRNA carries with itself a specific amino acid. As the mRNA codon is read, specific anticodon of tRNA with the amino acids keep attaching. The amino acids are linked to each other by means of a peptide bond and the tRNA is thrown for reusing. The process of translation stops when the mRNA shows its stop codon sequence. This sequence has no anticodon and hence no amino acid, so this puts a stop to the process of polypeptide synthesis.
Note that the protein synthesized depends on the message and information brought by the mRNA. For example, if you want to make some muscle protein, the message would be transcribed by the DNA into an mRNA, and then it would be translated into the protein, so it’s a step-wise process and a very specific one as well. Once the protein is synthesized it can be further processed by the Golgi apparatus and then exported out of the cell, where it can be used for different structural and functional roles.
