First molecules of life – Life's origin – (RNA)
One view is that an RNA world existed on Earth before modern cells arose. According to this hypothesis, RNA stored both genetic information and catalyzed the chemical reactions in primitive cells. Only later in evolutionary time did DNA take over as the genetic material and proteins become the major catalyst and structural component of cells.
All modern life on Earth uses three different types of biological molecules that each serve critical functions in the cell. The structure of the nucleic acids in a cell determines the structure of the proteins produced in that cell. Since proteins are the "building blocks" of life, nucleic acids can be considered the "blueprints" of life.
Proteins are the workhorse of the cell and carry out diverse catalytic and structural roles, while the nucleic acids, DNA and RNA, carry the genetic information that can be inherited from one generation to the next.
Many people are familiar with deoxyribonucleic acid (DNA), which is often referred to as the 'building blocks of life' because it contains the genetic material for its parent organism. RNA is equally important, even if it is lesser known, because RNA plays a critical role in helping DNA to copy and express genes, and to transport genetic material around in the cell.
RNA, which stands for ribonucleic acid, is a polymeric molecule made up of one or more nucleotides A strand of RNA can be thought of as a chain with a nucleotide at each chain link. Each nucleotide is made up of a base (adenine, cytosine, guanine, and uracil, typically abbreviated as A, C, G and U), a ribose sugar, and a phosphate.
RNA also has a number of independent functions which are no less important .Ribonucleic acid (RNA) is a chain of nucleotides present in the cells of all life. RNA has a number of important functions for living organisms, ranging from the regulation of gene expression to assistance with copying genes.