Tobacco mosaic virus is a tubular filament of size : -
A
300 × 10 nm
B
300 × 5 nm
C
300 × 20 nm
D
700 × 30 nm
The answer is C.
Solution
Tobacco mosaic virus (TMV), the first virus to be discovered and crystallised (Stanley, 1935), is a rod-shaped (helical) virus. It is about 300 nm long and about 18 nm in diameter (often rounded to 20 nm). It consists of a single strand of RNA (about 6400 nucleotides) wound in a helix, surrounded by about 2130 identical protein subunits (capsomeres). So TMV is a tubular filament of size about 300 × 20 nm.
ConceptDimensions of TMV
Biological Classification in past papers
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