With the exception of some viruses, all organisms originally store their genetic information as DNA (deoxyribonucleic acid) before making RNA (ribonucleic acid) through a process called ‘transcription’. RNA is then used to make proteins by a process called ‘translation’. Chemically, DNA and RNA both consist of nucleotides linked together. A nucleotide comprises a ribose sugar, a phosphate group and a nitrogenous base. The ribose sugar in DNA is different to that of RNA because it is missing a hydroxyl group (-OH – one oxygen joined to a hydrogen atom). This missing hydroxyl group from DNA makes it less reactive than RNA, making DNA a more stable carrier of genetic information.
Both have bases called adenine, cytosine and guanine; however, DNA has a base called thymine while RNA has a base called uracil, similar to thymine but lacking a methyl group (-CH3 – one carbon atom joined to three hydrogen atoms). DNA is also doublestranded and longer than RNA, usually single-stranded but able to fold back in on itself and catalyse reactions.
Answered by Chi Wing Man.