Page 77 - Miracles Within the Molecule

The arms of the DNA lad der
con sist of sugar and phos phate
mol e cu les. Some bases com -
bine with these arms with
hydro gen bonds.
As a result of this spe cial cre a -
tion, DNA is suf fi cient ly flex i ble
to rep li cate and trans mit data.

In every sin gle cell in your body, you have one of these mol e cu les,
far more intel li gent than you. That mol e cule is DNA.
The DNA mol e cule resem bles the sides of two spi ral stair cas es
revolv ing around each other in a helix. The "steps" are formed of sugar
and phos phate mol e cu les, attached to one anoth er with a rath er strong
spe cial bond known as the ester bond. This bond is a rath er strong one.
There is no hap haz ard sequence in the steps, or rungs between the two
arms of DNA. The rungs are joined togeth er with a spe cial lock ing sys -
tem and have four sep a rate ele ments: ade nine, gua nine, cyto sine and
thi a mine. Of these four nucle ot i des, Adenine and Guanine are large
mol e cu les and Cytosine and Thiamine are small. In order for rungs to
form in a reg u lar man ner, gua nine always appears oppo site cyto sine
and ade nine oppo site thi a mine. In this way—since small bases are
always oppo site larg er ones—the dis tance remains sta ble at all points,
the result being a reg u lar dou ble helix.
The chem i cal bond formed among these four con tra posed nucle ot -
i des is a hydro gen bond, and that the DNA mol e cule con sists of hydro -
gen bonds is par tic u lar ly sig nif i cant. As you'll recall, the dis tin guish ing

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