ABSTRACT
Large amounts of DNA are wound up and packed into the average cell. In fact, there is enough DNA in a 2 m. human body to stretch from the earth to the sun and back 50 times. One role of the topoisomerase is to facilitate the central genetic events of replication, transcription, and recombination via geometric manipulation of the DNA. The Crick-Watson DNA double helix consists of two strands of alternating sugar and phosphate units. Each 5-carbon sugar is attached to the phosphate unit on one side by the carbon atom designated 5', and to the phosphate unit on the other side by the carbon atom designated 3'. In order to detect differences in the 3-dimensional configuration of DNA molecules, the main techniques are centrifugation and agarose gel electrophoresis. The action of EB strain can be used in directed synthesis to change the linking and writhing number of circular duplex DNA molecules.
