Acellular organism - Virus viroids and Prions

🌑Overview 

🔴There are so many structure which are non cellular or acellular.

🔴They exist their presence around the cellular organism. They have some significant impact on living organism.

🌑Virus 

🔴A   Virus is non cellular organism that have a crystalline structure outside the living cell. 

🔴Once it come with contact of living cell than it uses the system of host cell and start to replicate with in host cell.

Remember 👌👌Acellular organism like virus, Viroids and Prions are not  getting any place in any Classification.

🔴Term virus has been taken from the word "Venom" by the Louis Pasteur. 

🔴Dmitri Ivanowsky in 1892 identified some disease causing particle from Tobacco mosaic disease. 

🔴These particles are smaller than bacteria because they can pass bacteria proof filters.

🔴M.W. Beijerineck in 1898 extracted the some fluid from plant affected  by Tobacco Mosaic disease. This infected fluid was renamed by "Contagium Vivum Fluidium" 

🔴W.M. Stanley in 1935 crystallized the virus particle and these Crystal are made up of protein. 

🔴Virus is non living outside the living cell and behaves like obligate parasite.

🔴Virus has a protein coat and its infectious genetic material is enclosed inside the protein cost. 

🔴The protein coat is called capsid which is made up of small subunit called capsomere. 

🔴Capsomeres are arranged helically or polyhedral geometric form.

🔴The genetic material or nucleic acid inside the protein is either DNA or RNA which contain nucleoprotein.

🔴Since virus has no ribosome , mitochondria or other cell organs hence virus is fully depend on cellular machinery on host for replication or protein synthesis.

🔴Virus with genetic material single stranded RNA infect the plants. 

🔴Mosaic formation, leaf curling or rolling, yellowing and vein clearing, dwarfism  stunted growth are symptoms of virus infection.

🔴Virus with genetic material single stranded or double stranded RNA and double stranded DNA  infect the animals. 

🔴Mumps, small pox, herpes influenza are vital disease.

🌑Viroids - 

🔴T. O. Dienier discovered a new infectious agent in spindle tuber disease of potato. 

🔴This agents is smaller than virus. It is devoid of protein coat but has free infectious RNA. Its RNA has low molecular weight.

🌑Prions - 

🔴It has been found that certain neurological infectious disease is transmitted by folded protein. 

🔴These infectious protein is called Prions. The size of prions are similar to virus. 

🔴Bovine Spongiform encephalopathy or mad cow disease in cattle is caused by Prions. Cr Jacob disease in human is also caused by the its variants.

1.Which of the following statement is not  correct.

A.  Virus is non cellular structure, may found In form of crystal out the living cell.

B.Term virus has been taken from the word venom by Jenner.   

C.  Virus uses the system of host cell and start to replicate with in host cell

D.  Virus are smaller than bacteria because they can pass bacteria proof filters.

Answer : B  

2. Dmitri Ivaonowsky  discovered virus which were causing

A. Spindle tuber disease

B. Late blight of Potato

C. Loose smut of wheat.

D. Tobacco Mosaic disease.

Answer: D  

 

3. M.W. Beijerineck used term "Contagium vivum fluidium" for 

A. Infected fluid of virus

B. Naked genetic material 

C. Infected protein coat.

D. Infected fluid exist in various disease.

Answer: A  

4.Who of the following crystallises virus particle out side the living cell.

A. Louis Pasteur

B. M.W. Beijerineck 

C. W.M. stanley

D. Dmitri Ivanowsky 

Answer: C  

5. How many statement is /are correct .

1. Virus is obligate parasite. 

2. Viral protein coat is called capsomere which is made up of small unit capsid.

3. Capsomere are hellically or  polyhedral geometrically arranged.

4. Virus has  both DNA and RNA. 

5. Virus containing double stranded RNA generally causes disease in plants.

A. Two         B. Four 

C. Three       D. Five 

Answer: A  

6. Virus that causes disease in animal including human  have 

A. Single stranded RNA

B. Double stranded RNA

C. Double stranded DNA

D. All of the above.

Answer : D  

7. Virus that causes disease in plants   have 

A. Single stranded RNA

B. Double stranded RNA

C. Double stranded DNA

D. All of the above.

Answer : A   

8. Which of the following pair of disease is not caused by the virus.

A. Pneumonia and Typhoid

B. Small pox and Herpes

C. Mumps and influenza 

D. All of the above. 

Answer: A  

9. Consider the following symptoms in plants of viral disease and select the correct code;

1. Leaf curling 

2. Leaf rolling 

3. Vein clearing

4. Yellowing of leaf

A. 1,2  and 3 

B. 2, 3  and 4

C. 1,3 and 4

D. 1, 2,3 and 4 

Answer: D  

 10. Consider the following statement and select the correct code:

1. T.O. Dienier discovered viroids.

2. He discovered this infectious agent from spindle tuber disease of potato.

A. Only 1   B. Only 2 

C. Neither 1 nor 2

D. Both 1 and 2 

Answer: D  

11. Which of the following statement is not correct for the viroids.

A. Viroids is smaller than virus.

B. It has infectious genetic material only

C. It is devoid of protein coat.

D. Its RNA has high molecular weight.

Answer: D  

12. Which of the following infectious agent causes neurological diseases.

A. Virus     B. Viroids

C. Prions    D. Bacteria

Answer : C  

13. Bovine Spongiform encephalopathy or mad cow disease in cattle is caused by 

A. Bacteria    B. Virus 

C. Viroids      D. None of the above

Answer: D  

14. How many statement is / are correct.

1. Prions are folded infectious protein.

2. The size of prions is small than virus.

3. Prions has RNA or DNA.

4. Cr Jacob disease in human is caused by variant of prions.

A. One       B. Two 

C. Three    D. Zero

Answer: B