15.3 DNA

223

Fig. 15.4 A stack of

polymerized base pairs (left)

distorted (right) by slightly

twisting in order to form the

double helix (after Ageno,

1967; reproduced with

permission of the Accademia

dei Lincei)

gene manipulation, as discussed in Part III. During in vivo replication, as discussed

in the previous chapter, the chains are only separated locally.

Table 15.5 summarizes some significant discoveries relating to DNA.

It is now recognized that the structure, especially the sequence- and modification-

dependent rigidity (bending modulus), plays a profound rôle in the fidelity of repli-

cation, the regulation of transcription,² and the movement of DNA through crowded

milieux. The last aspect is of practical importance in DNA fractionation for sequenc-

ing, and so forth.

2 Protein–DNA structures also play a rôle here (Sect. 14.4.4), as do noncanonical DNA structures

(Makova and Weissenteiner, 2022).