Tobacco mosaic virus (TMV) is a simple rod-shaped helical virus that contains single stranded RNA situated at its middle and is surrounded by a protein coat called capsid. After tobacco mosaic virus enters its infected host cells through mechanical inoculation, it removes its capsid to release its single stranded viral nucleic acid which is then transported into the nucleolus. The single stranded viral RNA actuates the production of specific enzymes (RNA polymerases) and it also produces another RNA strand (replicative RNA). The new viral-RNAs are transported from the nucleus into the cytoplasm and functions as messenger-RNAs (mRNAs). Each mRNA, ribosomes, and t-RNA, of the infected host cell all controls the production of protein subunits (capsomeres). After the production of the preferred capsomeres, the new viral-RNAs arrange the capsomeres around it which lead to the production of a complete virus particle (virion). The viruses then migrate from one cell to another. Hence, creating organized infection.
The general shape of the epithelial cells that are nearest
to the lumen in an empty urinary bladder is in multiple cell layers which are
considered to be a stratified tissue and the cells in it are shaped in terms of
the organ’s distention. This type of epithelial cell is the transitional
epithelium.
