Читать книгу Cell Biology - Stephen R. Bolsover - Страница 63

The two strands of DNA are said to be antiparallel because they lie in the opposite orientation with respect to one another, with the 3′‐hydroxyl terminus of one strand opposite the 5′‐phosphate terminus of the second strand. The sugar‐phosphate backbones do not completely conceal the bases inside. There are two grooves along the surface of the DNA molecule. One is wide and deep – the major groove – and the other is narrow and shallow – the minor groove (Figure 3.4). DNA‐binding proteins can use the grooves to gain access to the bases and bind to specific sequences. This is important in initiating replication (page 51) and transcription (page 69) and is also used when manipulating DNA in the laboratory.

Figure 3.4. The DNA double helix is held together by hydrogen bonds.