Ribosomes are small granular molecules that exist freely in the cytoplasm of the cell or are attached to the nuclear envelope of the endoplasmic reticulum and play an important role in protein synthesis.
Physical and chemical structure of ribosomes
Physical structure: Ribosomes are usually round or oval in shape. Its average diameter is 90°A-160°A. Each ribosome is enveloped by a bilayer membrane. Usually, many ribosomes are joined in a row by a RAN formula to form polyribosomes. Each ribosome consists of two subunits. The sub-units are unequal. One of them is large and domed and the other is small and somewhat hemispherical. The small subunit is attached to the large subunit like a cap. The ribosome particle is attached to the core of the endoplasmic reticulum with the help of the large subunit.
Chemical Structure: Ribosomes are mainly composed of RNA and proteins. Analysis of ribosome shows that it contains mRNA, nRNA, protein, lipids, and metal ions (eg magnesium ion Mg + calcium ion Cat'). A true cell's ribosome contains 70-80 proteins.
Functions of Ribosomes : (i) Plays important role in protein synthesis,
(ii) Ribosomes produce cytochromes which transport electrons in cellular respiration.
(iii) Metabolism of neurotransmitters,
(iv) Initiation of replication, amino acids, polymerization and termination of polypeptide chain take place in ribosomes.
(v) Glucose phosphorylation takes place in ribosomes; (vi) Protects mRNA from the action of nuclear enzymes.
I am a student of zoology and credit for this article goes to Madam Rita Parvin, Sir Shamol Shordar, Sir MD Rafikul Islam, Sir Shafiullah Shopon