Chapter 1: DNA structure

DNA is an icon of the 20th century and is familiar to most people. However, this familiarity does not generally extend to an understanding of DNA structure. The purpose of this book is to focus on higher order structural features of DNA, such as supercoiling, knotting and catenation. However, in order to deal with these topics we must first understand the primary and secondary features of DNA, which are the subject of Chapter 1.

We begin with describing the constituents of DNA (sugar, bases, phosphate) and how these are linked together to make the DNA polymer. We show how two strands of DNA can be linked together by hydrogen bonding to form the DNA double helix. We describe the principal helical forms of double-stranded DNA and discuss their properties. Following this, alternative DNA structures are described: cruciforms, triplexes and quadruplexes, and their biological significance is discussed. The chapter ends with descriptions of DNA curvature and flexibility, setting the scene for issues that come up in later chapters.

Click on the thumbnails below for full-size versions of the illustrations in Chapter 1.

Alternatively, you can download a zip file containing all the figures for Chapter 1.

Figures

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Figure 1.10