Birefringence and elasticity of overstretched DNA

The conformation of DNA when it interacts with enzymes is not yet well known. To find out more about it and the overstretched state during the process several methods can be applied. One of them is to measure the birefringence of an artificially overstretched molecule. This matter is discussed in the following chapters. Parts of the experiments are the chemical treatment of the DNA to attach it to a surface, using a Surface Force Apparatus, focusing a laser to pass DNA within 10 µm, fluorescent microscopy, electrophoresis and to use supermagnetic beads to manipulate the molecules. All these steps are briefly described.We were able to measure birefringence of stretched DNA, but not the birefringence of overstretched DNA. As a results of the research we gained a lot of information about the techniques and the birefringence measurement. This report of research gives an idea of the problems and possible solutions of those processes