This article clarifies the difference between DNA and RNA.
RNA is very similar to DNA, but differs in a few important structural details: RNA nucleotides contain ribose sugars while DNA contains de-oxy-ribose (a type of ribose that lacks one oxygen atom) and RNA uses predominantly uracil instead of thymine present in DNA.
RNA is usually single-stranded, while DNA is usually double-stranded. RNA is transcribed from DNA by enzymes called RNA polymerases and further processed by other enzymes. But there are some exceptions where RNA is double stranded and DNA is single stranded. Examples of double stranded RNA are reo-virus, retrovirus, hepatitis-B virus etc. and the single stranded DNA is present in phage FX174 and parvovirus.
Unlike DNA, RNA is not the genetic material of most of the organisms. RNA is the genetic material of only some of the plant, animal and bacterial viruses. Such RNA is called as genetic RNA. However, RNA is present in all the organisms but perform different functions during protein synthesis. In them the genetic message are given by DNA and such RNAs are called as non genetic RNA. RNA serves as the template for translation of genes into proteins, transferring amino acids to the ribosome to form proteins, and also translating the transcript into proteins (Table 5.1, Fig. 5.2).