DNA Amplification and Tissue Culture -DNA sequence in eukaryotes can be resolved into three distinct classes differing in degree of redundancy: highly repetitive, intermediate, and unique.

Highly repetitive sequences are not transcribed.

The unique sequences belong to structural genes in the strict sense.

The intermediate group comprises interspersed short sequences and reiterated clusters of genes (e.g. ribosomal RNA, 5S RNA, t-RNA, histone messenger RNA).

Several hypotheses have been proposed with regard to the function of the different kinds of sequences. Up to now, however, no unifying theory has been proposed which might explain in teleological terms the reason for the large differences in multiplicity at the inter and intraspecific levels and their influence, if any, on plant developmental processes.