310

The secondary structures exert important functions of RNA in the regulation of transcrip­

tion, such as catalytic activity of ribosomes (ribozymes). RNA secondary structure folding

is a complex process; in addition to a complementary sequence, the folding energy must

also be considered. Whereby the following always applies: A pairs with U (two hydrogen

bonds), G pairs with C (three hydrogen bonds). But there are also other rules, for example

G pairs with U, only one hydrogen bond. In addition, the folding energy must also be

20  Solutions to the Exercises