DNA and RNA are somewhat similar organic molecules, both involved in the storage and transfer of genetic information. According to About.com, DNA’s primary function is to store genetic information over the long term, while RNA’s primary function is to transfer this information to the ribosomes, where proteins are made. Because they perform different functions, they have different structures, chemistry and characteristics.
About.com states that DNA stands for deoxyribonucleic acid, while RNA stands for ribonucleic acid. The difference in their names indicates the primary chemical difference between them, with RNA possessing the sugar ribose and DNA possessing deoxyribose. Ribose contains one more –OH group of atoms in each molecule than deoxyribose does, but it is missing a -H ion that is present in deoxyribose. DNA is susceptible to being damaged by ultraviolet rays, whereas RNA is somewhat resistant to damage from these rays. RNA molecules are susceptible to pH imbalances and do not remain stable when exposed to alkaline conditions, whereas DNA molecules remain stable under such conditions.
Structurally, the two look very different. As explained by About.com, RNA molecules are helically shaped, whereas DNA molecules take the form of a double helix. DNA molecules are able to produce RNA molecules by virtue of this double-sided design.