NCERT Class XII Chemistry
Chapter - Biomolecules
Questions with Solutions

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Question : 24
Total: 33
Write the important structural and functional differences between DNA and RNA.
Solution:  
Difference between DNA and RNA.
   DNA  RNA
 1.  It usually occurs inside nucleus and some cell organelles.  Very little RNA occurs inside nucleus. Most of it is found in the cytoplasm.
 2.  DNA is the genetic material.  RNA is not the genetic material except in certain viruses, e.g., TMV, Reovirus.
 3.  It is double stranded with a-helix structure in which two strands are coiled spirally.  RNA is single stranded with the exception of some viruses (e.g., double stranded in Reovirus).
 4.  DNA shows regular helical coiling.  There is no regular coiling except in parts of tRNA.
 5.  DNA is of only two types, nuclear and extra-nuclear.  There are at least three types of RNA-mRNA, rRNA and tRNA.
 6.  It contains deoxyribose sugar.  It contains ribose sugar.
 7.  Nitrogen base thymine occurs in DNA along with three other -adenine, cytosine and guanine.  Thymine is replaced by uracil in RNA. The other three are adenine, cytosine and guanine.
 8.  It has a unique property of replication.  It does not replicate.
 9.  DNA transcribes genetic information to RNA.  RNA translates the transcribed message for forming polypeptides.
 10.  DNA controls heredity, evolution, metabolism, structure and differentiation.  RNA controls only protein synthesis.
 11.  DNA controls metabolism and genetics including variations.  It only controls metabolism under instructions from DNA.
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