RNA is an acronym for ribonucleic acid, a nucleic acid. Many different kinds are now known.
RNA is physically different from DNA: DNA contains two intercoiled strands, but RNA only contains one single strand. RNA also contains different bases from DNA. These bases are the following:
(A) Adenine
(G) Guanine
(C) Cytosine
(U) Uracil
Adenine often forms bonds with uracil, and guanine often forms bonds with cytosine. In this way, we say that adenine is complementary to uracil and that guanine is complementary to cytosine. The first three bases are also found in DNA, but uracil replaces thymine as a complement to adenine.
RNA also contains ribose as opposed to deoxyribose found in DNA. These differences result in RNA being chemically more reactive than DNA. This makes it the more suitable molecule to take part in cell reactions.
RNA is the carrier of genetic information in certain viruses, especially the retroviruses like the HIV virus. This is the only exception to the general rule that DNA is the hereditary substance.

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