The length of the TMV is about 17 times the width. Width 15-18 nm and length 280-300 nm. It consists of two parts. Nucleic acid and capsid.
1. Nucleic acid: The core of nucleic acid in the center of the virus is called nucleoid. At its center is a single-stranded RNA. The cone-shaped cavity between the patches of RNA is 4nm in diameter. RNA content in TMV is 5%. The RNA sequence is made up of 6500 nucleotides. Its molecular weight is 2.4 million daltons. It carries the genetic characteristics of the virus and plays a role in the synthesis of new viruses.
2. Capsid: The outer coat of nucleic acid is called capsid. It is made up of numerous protein molecules. It contains 95% protein. Each protein molecule in the capsid is called a capsomer. TMV contains 2130-2200 capsomeres. Each capsomer is composed of 158 amino acids. Each protein subunit has a molecular weight of 17,000 daltons. The capsid acts as an antigen and protects the acid core. Dr. Siddiq Publications