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WHAT IS THE DIFFERENCE BETWEEN DNA & RNA
The main difference between DNA and RNA is the sugar present in the molecules. While the sugar present in an RNA molecule is ribose, the sugar present in a molecule of DNA is deoxyribose. Deoxyribose is the same as ribose, except that the former has one more OH.

DNA does not usually exist as a single molecule, but instead as a tightly-associated pair of molecules. These two long strands entwine like vines, in the shape of a double helix. This arrangement of DNA strands is called antiparallel. The asymmetric ends of DNA strands are referred to as the 5? (five prime) and 3? (three prime) ends. One of the major differences between DNA and RNA is the sugar, with 2-deoxyribose being replaced by the alternative pentose sugar ribose in RNA. The four bases found in DNA are adenine (abbreviated A), cytosine (C), guanine (G) and thymine (T). A fifth pyrimidine base, called uracil (U), usually takes the place of thymine in RNA and differs from thymine by lacking a methyl group on its ring.
Deoxyribose sugar in DNA is less reactive because of C-H bonds. Stable in alkaline conditions. DNA has smaller grooves, which makes it harder for enzymes to "attack" DNA.
Ribose sugar is more reactive because of C-OH (hydroxyl) bonds. Not stable in alkaline conditions. RNA has larger grooves, which makes it easier to be attacked by enzymes.
DNA is self replicating where as RNA is synthesized  from DNA when needed.


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