MIT News ran this nice profile of the 7.00x Introduction to Biology course a while back.  A glimpse into the thinking behind MITx offerings:

The MIT introductory biology course now being offered online through edX is simultaneously something old and something new: a version of a beloved MIT course that for decades has been taught by senior faculty to packed lecture halls, and the latest offering of the interactive learning platform launched less than a year ago by MIT and Harvard University.
MIT’s 7.00x (Introduction to Biology: “The Secret of Life”), which began March 5 and runs for 12 weeks, is one of three new courses offered this semester through edX. There are now six MIT edX courses in total.
The online course is taught by senior members of the MIT Department of Biology: Eric Lander and Graham Walker.
“It gives us a chance to rethink the course and to think about new ways to use electronic media at MIT, and that’s pretty exciting,” says Lander, a professor of biology who is also director of the Broad Institute. Read more.

Explore some of the great introductory biology courses on OCW: