How do the cells in your body define their boundaries (and control what comes in or goes out)? As it turns out, cells have a sophisticated and flexible barrier, the plasma membrane, and a wide array of strategies for transporting molecules in and out. Learn more about what the membrane’s made of and how different types of molecules move across it.
Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computing, history, art history, economics, and more, including K-14 and test preparation (SAT, Praxis, LSAT) content. We focus on skill mastery to help learners establish strong foundations, so there's no limit to what they can learn next!