ADN renaturé

OBS: Heating DNA molecules to temperatures just below 100 [degrees] C breaks the hydrogen bonds holding the complementary strands together; they then quickly separate from each other (DNA denaturation). If the temperature is gradually lowered, the complementary strands again form the correct hydrogen bonds and the double-helical form is regained (renaturation of DNA). If, however, this gentle cooling is done in the presence of single-stranded RNA that has been synthesized on homologous DNA, then DNA-RNA hybrids form as well as denatured DNA double helices. These DNA-RNA hybrids are very specific and form only if some of the nucleotide sequences in the DNA are complementary to the RNA nucleotide sequences.