<P> The GC pair is bound by three hydrogen bonds , while AT and AU pairs are bound by two hydrogen bonds . To emphasize this difference in the number of hydrogen bonds , the base pairings can be represented as respectively G ≡ C versus A = T and A = U. DNA with low GC - content is less stable than DNA with high GC - content ; however , the hydrogen bonds themselves do not have a particularly significant impact on stabilization , the stabilization is due mainly to interactions of base stacking . In spite of the higher thermostability conferred to the genetic material , it has been observed that at least some bacteria species with DNA of high GC - content undergo autolysis more readily , thereby reducing the longevity of the cell per se . Due to the thermostability given to the genetic materials in high GC organisms , it was commonly believed that the GC content played a necessary role in adaptation temperatures , a hypothesis that was refuted in 2001 . However , it has been shown that there is a strong correlation between the prokaryotic optimal growth at higher temperatures and the GC content of structured RNAs ( such as ribosomal RNA , transfer RNA , and many other non-coding RNAs ) . The AU base pairs are less stable than the GC base pairs previously attributed to GC bonds containing 3 hydrogen bonds and AU having only 2 hydrogen bonds , making high - GC - content RNA structures more resistant to the effects of high temperatures . More recently , it has been proved that the most stabilizing factor of thermal stability of double stranded nucleic acids is actually due to the base stackings of adjacent bases , rather than the number of hydrogen bonds between the bases. There is more favorable stacking energy for G : C pairs because of the relative positions of exocyclic groups than in the A : U pairs . Additionally , there is a correlation between the order in which the bases stack and thermal stability . </P>
<P> The GC pair is bound by three hydrogen bonds , while AT and AU pairs are bound by two hydrogen bonds . To emphasize this difference in the number of hydrogen bonds , the base pairings can be represented as respectively G ≡ C versus A = T and A = U. DNA with low GC - content is less stable than DNA with high GC - content ; however , the hydrogen bonds themselves do not have a particularly significant impact on stabilization , the stabilization is due mainly to interactions of base stacking . In spite of the higher thermostability conferred to the genetic material , it has been observed that at least some bacteria species with DNA of high GC - content undergo autolysis more readily , thereby reducing the longevity of the cell per se . Due to the thermostability given to the genetic materials in high GC organisms , it was commonly believed that the GC content played a necessary role in adaptation temperatures , a hypothesis that was refuted in 2001 . However , it has been shown that there is a strong correlation between the prokaryotic optimal growth at higher temperatures and the GC content of structured RNAs ( such as ribosomal RNA , transfer RNA , and many other non-coding RNAs ) . The AU base pairs are less stable than the GC base pairs previously attributed to GC bonds containing 3 hydrogen bonds and AU having only 2 hydrogen bonds , making high - GC - content RNA structures more resistant to the effects of high temperatures . More recently , it has been proved that the most stabilizing factor of thermal stability of double stranded nucleic acids is actually due to the base stackings of adjacent bases , rather than the number of hydrogen bonds between the bases. There is more favorable stacking energy for G : C pairs because of the relative positions of exocyclic groups than in the A : U pairs . Additionally , there is a correlation between the order in which the bases stack and thermal stability . </P>
how many hydrogen bonds form between g and c
how many hydrogen bonds form between g and c
three
three