MOOCs are Massively Open Online Courses. They don't usually offer real college credit, but are taught at a college level, though entirely online. Often, thousands of students from all over the world participate in a single course. You can audit, or pay a small fee to get a nice certificate if you pass.
Students can discuss issues or ask questions of the staff via online forums.
The professor is Rice University's Dr. Alma Moon Novotny, who is quite a personality. She often uses cartoons drawn by students to illustrate different kinds of cells and their interaction.
At Rice we require students to have passed either Introductory Biochemistry or AP Biology with a score of 4 or better. If you’ve taken Eric Lander’s edX course on “The Secret of Life,” that should do it too. You are welcome in at whatever preparation level you have, but the more you know, the easier it will be to understand the material.
We anticipate spending between 7-10 hours per week, depending on background."
Unlike most MOOCs, the quizzes are closed book, on the honor system.
A second part of the course will start in October.
I didn't have adequate preparation in the 1st offering of the course, but am now finishing up Dr. Eric Lander's MIT course mentioned above.