Group carriers are important in catalytic processes, preventing the loss of substrates. This allows enzymes to identify where the substrate is, allowing the two to be brought together - as opposed to waiting for a successful binding. With small substrates, that may be in low concentrations, this increases rate as the substrate can be ‘found’ easily.
Group carriers are involved in genetic information storage, by helping in the synthesis of nucleotides, bases, and other molecules found in or associated with DNA. Group carriers are not (known to be) directly involved in DNA once the molecule has been synthesised.