Which of the following is correct about viroids? [2020]
They have RNA with protein coat.
They have free RNA without protein coat.
They have DNA with protein coat.
They have free DNA without protein coat.
(2)
Viroids are free RNA particles that lack protein coat. They are infectious agents smaller than viruses.
Mad cow disease in cattle is caused by an organism which has [2019]
inert crystalline structure
abnormally folded protein
free RNA without protein coat
free DNA without protein coat
Which of the following statements is incorrect? [2019]
Prions consist of abnormally folded proteins.
Viroids lack a protein coat.
Viruses are obligate parasites.
Infective constituent in viruses is the protein coat.
(4)
Infective constituent in the viruses is the genetic material, i.e., either DNA or RNA.
Viroids differ from viruses in having [2017]
DNA molecules without protein coat
RNA molecules with protein coat
RNA molecules without protein coat
DNA molecules with protein coat
(3)
Viroids are free RNA particles that lack protein coat. They are infectious agents smaller than viruses.
Which of the following statements is wrong for viroids? [2016]
They cause infections.
Their RNA is of high molecular weight.
They lack a protein coat.
They are smaller than viruses.
(2)
RNA of viroid has low molecular weight.
Select the wrong statement. [2015]
The term 'contagium vivum fluidum' was coined by M.W. Beijerinck.
Mosaic disease in tobacco and AIDS in human beings are caused by viruses.
The viroids were discovered by D.J. Ivanowsky.
W.M. Stanley showed that viruses could be crystallised.
(3)
Viroids are infectious RNA particles which were discovered by T.O. Diener (1971). These are devoid of protein coat and cause diseases in plants only, e.g., potato spindle tuber, chrysanthemum stunt, etc.
Which of the following shows coiled RNA strand and capsomeres? [2014]
Polio virus
Tobacco mosaic virus
Measles virus
Retrovirus
(2)
Tobacco mosaic virus is a RNA virus that causes tobacco mosaic disease. It has a single-stranded coiled RNA molecule as its genetic material, a part of which hangs outside the protein coat. The protein coat consists of approximately 2130 capsomeres, which are helically arranged to form a hollow cylinder of about 4 nm diameter.
Viruses have [2014]
DNA enclosed in a protein coat
prokaryotic nucleus
single chromosome
both DNA and RNA
(1)
Viruses are nucleoprotein entities which are able to utilize synthetic machinery of a living cell of the host organism for its multiplication which does not involve growth and division. They have either RNA or DNA as genetic material and a protein coat.
