In DNA<span>, the code letters are A, T, G, and C, which stand </span>for<span> the chemicals </span>adenine<span>, thymine, guanine, and cytosine, respectively. In base pairing, </span>adenine always pairs<span> with thymine, and guanine </span>always pairs<span> with cytosine.</span>
Enzymes speed up the chemicaal reaction .
When you get a bruise, capillaries the smallest blood vessels get busted and release blood which will be trapped beneath the skin as a result of the trauma or impact which may be a blow or a cut
