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“Hydrogen bonds

“Hydrogen bonds influence the structure of all living things. The double helix of DNA is held together by hydrogen bonds. The same is true of the structure of all the protein molecules of our body, from those in the largest organs, such as our muscles and our brain, to the smallest components of cells, such as enzymes. Hydrogen bonds are generally formed between molecules containing oxygen and nitrogen atoms, and occur when a hydrogen attached to one of these atoms in a molecule is attracted to an oxygen or nitrogen atom in another molecule. The two molecules are drawn close together by means of a so-called ‘hydrogen bond’.

“In living things the most imortant type of hydrogen bond is between nitrogen and oxygen; these are the ones that hold together the strands of DNA. The genetic code of DNA is represented by the letters A, C, G and T, which stand for the bases adenine, cytosine, guanine and thymine. A and T pair up by forming two hydrogen bonds, while C and G do so by forming three hydrogen bonds. Because these combinations are so well matched, when a strand of DNA separates in order to form a copy of itself, it does so exactly, because each A, C, G and T uses its hydrogen bonds to ensure a match with the right partner.

“Although hydrogen bonds are weak compared with normal bonds, having less than a quarter of the energy of these, there are many of them and quanity makes up for quality.”

Nature’s Building Blocks [pg. 189].