Basic Molecular Biology: Basic Science – RNA Structure

Ribonucleic acid, or RNA, is similar in structure to DNA, but is involved in very different cellular functions. Similar to DNA structure, RNA consists of the same basic elements, a sugar-phosphate However, there are three major differences that account for the very different functions of the two molecules. RNA is a single-strand nucleic acid, which, while more unstable than DNA, allows flexibility to bend back on itself, forming weak bonds with another part of the same molecule. Secondly, RNA has a ribose sugar instead of deoxyribose sugar like DNA, which is important for enzymes that distinguish DNA from RNA. Lastly, RNA has a uracil-nitrogen base instead of the thymine, allowing the base-pair complementary rule. Adenine binds to uracil, and cytosine binds to guanine. For orientation purposes, the carbon atoms in the ribose sugar are numbered similarly 1-5 with corresponding 3' and 5' ends. Adjoining nucleotides add on to the 3' hydroxyl group of the previous nucleotide. Functionally, cells contain a variety of forms of RNA including messenger RNA or mRNA, transfer RNA or tRNA, and ribosomal RNA or rRNA. Each form assists in the many functions of the cell such as coding, decoding, regulating, and expressing genes.