Ribonucleic acid (RNA)

RNA is an essential biomolecule involved in heredity and protein synthesis. It resembles DNA in being made of nucleotides, but it differs in sugar type, one nitrogenous base, and overall structural organisation.

• RNA is usually single-stranded.
• It is composed of repeating units called ribonucleotides.

Each ribonucleotide contains:

• one ribose sugar,
• one phosphate group,
• one nitrogenous base.

The nucleotides are joined by phosphodiester bonds to form a polynucleotide chain.

A polynucleotide of RNA:

Nitrogenous Bases in RNA

The nitrogenous bases present in RNA are:

1. Adenine (A)
2. Guanine (G)
3. Cytosine (C)
4. Uracil (U)

In RNA, uracil replaces thymine. Therefore, when complementary pairing occurs in RNA, adenine pairs with uracil.

Sugar-Phosphate Backbone

The backbone of RNA is formed by alternating ribose sugar and phosphate units. This backbone provides structural support to the RNA molecule.

Building blocks of RNA:

Why RNA Is Different from DNA

The major structural differences are:

• RNA contains ribose sugar, while DNA contains deoxyribose sugar.
• RNA contains uracil, while DNA contains thymine.
• RNA is generally single-stranded, while DNA is usually double-stranded.

• RNA is a nucleic acid that is usually single-stranded and made of ribonucleotides linked by phosphodiester bonds.
• RNA contains ribose sugar and the bases adenine, guanine, cytosine, and uracil, with uracil present instead of thymine.
• The backbone of RNA consists of alternating ribose and phosphate groups, forming a flexible single-stranded chain.
• RNA plays a central role in gene expression by acting as an intermediate between DNA and proteins.
• Major types of RNA are mRNA, tRNA, and rRNA, each with specific roles in protein synthesis.