Biochemistry

Molecules R US
This is a very important site for anyone interested in examining the three-dimensional structure of biological molecules. This site from the Computational Molecular Biology group at the National Institutes of Health (NIH) provides access to the Brookhaven Protein Data Bank (PDB). The files in the database -- called PDB files -- contain information on the 3D structure of molecules and can be used in a variety of ways including:

within a web browser as a GIF image
as an interactive 3D model within a web browser by using the Chime plugin
as a downloadable file to be used in an external modeling application like RasMol, MacMolecule/PCMolecule or MolView

The main interface is very simple in that you enter the name of a molecule you are interested in (in spite of database's name, you are not limited to protein molecules). The database returns a list of files that match the search criterion and a short description of the file. Clicking on a file's name takes you to a screen where you select the format in which you want the information displayed. There is also a new interface ("PDB At A Glance") under development that lists the PDB files by type of molecule and is more suited to browsing the database. Recommended: Chime plugin

RasMol Home Page
Wow, this is a must-see site. RasMol is a free application (Windows, UNIX and Macs) for 3D visualization of molecules. With it you can open downloadable files that contain information on the three-dimensional structure of molecules and then use the program to rotate the molecule and change its appearance (e.g., space-filling model, ball-and-stick model, etc.) There is a "Quickstart" guide for using the application that will get you up to speed in no time. There are also other free applications from other sources that do similar things including MacMolecule/PCMolecule and MolView

Chime is a free browser plugin that is built upon RasMol and allows for viewing of the 3D structure files directly within a web browser. After installation of the plugin, the user can download and view structure files from the web (e.g., from Molecules R US) or take advantage of one of the many tutorials available from this site. (Note: you do not need RasMol installed on your computer to use the Chime plugin.)

Internet Chemistry
Reduction/oxidation reactions are the topic at this site provided by Kapiolani Community College. This is a very thorough treatment of the subject and is enhanced with interactive quizzes.