The following points highlight the five main steps involved in purification of plant viruses. 1. Infected leaves are thoroughly homogenized in water or preferably in phosphate, borate or citrate buffer in an electric grinder or in a mortar with pestle (Fig. 13.15). 2. Tissue homogenate is strained through a piece of muslin cloth (or cheese cloth). Crude sap which comes [...]
In this article we will discuss about the structure and replication of Tobacco Mosaic Virus (TMV). Structure of Tobacco Mosaic Virus (TMV): TMV is a simple rod-shaped helical virus (Fig. 13.20) consisting of centrally located single- stranded RNA (5.6%) enveloped by a protein coat (94.4%). The rod is considered to be 3,000 Å in length and about 180 Å in [...]
In this article we will discuss about the classification and morphological groups of bacteriophages. Classification of Bacteriophages: On the basis of presence of single or double strands of genetic material, the bacteriophages are categorized as under: 1. The ssDNA Bacteriophages: (i) Icosahedral phages = φx 174, St-1, φR, BR2, 6SR U3 and G series, e.g., G4, G6, G13, G16. All [...]