Scitable: expand your learning experience

Bookmark this site and browse its contents. Clear, short easy to read articles on several topics of biology (including genetic expression). You can even engage in networking with students around the world.

In addition, a very useful topic on scientific communication that will help you to improve your communication skills. This is almost as much important as obtaining good experimental data!

Topoisomerases and DNA winding and unwinding

Although this example refers to replication, it fits perfectly to transcription. Note that when in the video it is asked "How does DNA solve this knotty problem?", the author should have posted something like "How is the problem solved?". I mean, how does DNA knows that there is a problem and how does DNA decides to solve the problem? It is just a molecule! What they should have said is that evolution provided mechanisms that solve the problem of torsional tension (winding and unwinding) of DNA during replication and transcription.