Ribonucleic acids, also called RNA, perform multiple important roles in living cells. RNA is needed for protein synthesis and DNA* replication. RNA containing molecules also contribute to the regulation of gene expression and function as enzymes.
Like DNA, RNA polymers are make up of chains of nucleotides*. These nucleotides have three parts: 1) a five carbon ribose sugar, 2) a phosphate molecule and 3) one of four nitrogenous bases: adenine, guanine, cytosine or uracil.
RNA nucleotides form polymers of alternating ribose and phosphate units linked by a phosphodiester bridge between the #3 and #5 carbons of neighboring ribose molecules.
RNA nucleotides differ from DNA nucleotides by the presence of a hydroxyl group linked to the #2 carbon of the sugar. The presence of this hydroxyl group allows RNA polymers to assume a more diverse number of shapes compared to DNA polymers. The extra hydroxyl group also makes RNA polymers less stable than DNA polymers.
The greater variety of shapes RNA polymers are able to form, is part of the reason RNA serves more functions than DNA.
Test your understanding of the concepts covered by answering the Nucleotides in RNA practice problems