RNA- Properties, Structure, Types and Functions


RNA, or ribonucleic acid, is a type of nucleic acid that plays a vital role in the expression of genetic information. RNA is similar to DNA, or deoxyribonucleic acid, in that it is composed of nucleotides, which are the building blocks of nucleic acids. However, RNA differs from DNA in several aspects, such as its structure, composition, and function.

Structure of RNA

The basic structure of RNA is a single-stranded helix, which means that it has only one strand of nucleotides that forms a twisted shape. Unlike DNA, which has two complementary strands that form a double helix, RNA can fold back on itself and form base pairs within the same strand. This creates regions of double-strandedness and complex shapes in some RNA molecules.

Each nucleotide in RNA consists of three components: a nitrogenous base, a pentose sugar, and a phosphate group. The nitrogenous bases in RNA are adenine (A), guanine (G), cytosine (C), and uracil (U). Uracil replaces thymine (T), which is found in DNA, as the complementary base to adenine. The pentose sugar in RNA is ribose, which has an extra hydroxyl group compared to deoxyribose in DNA. The phosphate group connects the sugar of one nucleotide to the sugar of the next nucleotide, forming a backbone for the RNA strand.

The nucleotides in RNA are linked by 3′ –> 5′ phosphodiester bonds, which means that the 3′ hydroxyl group of one nucleotide is attached to the 5′ phosphate group of another nucleotide. This creates a polarity for the RNA strand, which has a free 5′ phosphate group at one end and a free 3′ hydroxyl group at the other end. The directionality of the RNA strand is important for its interaction with other molecules, such as proteins and enzymes.

The sequence of nucleotides in RNA determines its function and specificity. Different regions of the RNA strand can have different roles and interactions depending on their base composition and structure. For example, some RNA molecules have a 5′ cap and a 3′ poly-A tail that protect them from degradation and facilitate their transport and recognition. Some RNA molecules have a codon region that encodes for amino acids and a non-coding region that regulates their expression. Some RNA molecules have an anticodon region that matches with a codon region and an amino acid attachment site that carries an amino acid.

The structure of RNA is dynamic and flexible, allowing it to adopt various conformations and perform diverse functions. Some RNA molecules can act as catalysts, sensors, regulators, or messengers in various biological processes. The diversity and versatility of RNA make it an essential molecule for life.