<Dd> The ability to conjugate an amino acid to the 3' - end of an RNA in order to use its chemical groups or provide a long - branched aliphatic side - chain . </Dd> <Dt> Peptide bond formation </Dt> <Dd> The ability to catalyse the formation of peptide bonds between amino acids to produce short peptides or longer proteins . This is done in modern cells by ribosomes, a complex of several RNA molecules known as rRNA together with many proteins . The rRNA molecules are thought responsible for its enzymatic activity, as no amino acid molecules lie within 18 Å of the enzyme's active site, and, when the majority of the amino acids in the ribosome were stringently removed, the resulting ribosome retained its full peptidyl transferase activity, fully able to catalyze the formation of peptide bonds between amino acids . A much shorter RNA molecule has been synthesized in the laboratory with the ability to form peptide bonds, and it has been suggested that rRNA has evolved from a similar molecule . It has also been suggested that amino acids may have initially been involved with RNA molecules as cofactors enhancing or diversifying their enzymatic capabilities, before evolving to more complex peptides . Similarly, tRNA is suggested to have evolved from RNA molecules that began to catalyze amino acid transfer . </Dd> <P> RNA is a very similar molecule to DNA, and only has two chemical differences . The overall structure of RNA and DNA are immensely similar--one strand of DNA and one of RNA can bind to form a double helical structure . This makes the storage of information in RNA possible in a very similar way to the storage of information in DNA . However, RNA is less stable . </P>

Is mrna the only type of rna found in the living system