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TED-Ed Original lessons feature the words and ideas of educators brought to life by professional animators. Are you an educator or animator interested in creating a TED-Ed original? Nominate yourself here »

Meet The Creators

Biljana Labovic

Celeste Lai

Ethan Perlstein

Lisa LaBracio

Animation Artist


Additional Resources for you to Explore

Ethan O. Perlstein focuses "on the intersection of cell biology, personalized medicine and quantitative evolutionary theory – a cross-disciplinary perspective I call evolutionary pharmacology."

Agnes Luise Wilhelmine Pockels was a German pioneer in chemistry.

Irving Langmuir (1881–1957) and Katharine Burr Blodgett (1898–1979), research pioneers for the General Electric Company (GE), enjoyed one of the most fruitful relationships between a mentor and a younger scientist of all time. Among their many accomplishments, they were able to create and study films, or coatings, that were just one molecule thick.

The transport of gaseous compounds across biological membranes is essential in all forms of life. Although it was generally accepted that gases freely penetrate the lipid matrix of biological membranes, a number of studies challenged this doctrine as they found biological membranes to have extremely low gas-permeability values. These observations led to the identification of several membrane-embedded “gas” channels, which facilitate the transport of biological active gases, such as carbon dioxide, nitric oxide, and ammonia. However, some of these findings are in contrast to the well-established solubility–diffusion model (also known as the Meyer–Overton rule), which predicts membrane permeabilities from the molecule's oil–water partition coefficient. Herein, we discuss recently reported violations of the Meyer–Overton rule for small molecules, including carboxylic acids and gases, and show that Meyer and Overton continue to rule.

The lipids are a large and diverse group of naturally occurring organic compounds that are related by their solubility in nonpolar organic solvents (e.g. ether, chloroform, acetone & benzene) and general insolubility in water.

Think you know all there is to know about lipids? Here's a list of all the websites that mention, teach about, relate to, or involve fats and lipids.

About seven decades ago, Gorter and Grendel, the "founding fathers" of our current model of plasma membrane structure, predicted quite simply that if a plasma membrane were really a bilayer then its surface area should be half that occupied by all its amphipathic lipids spread out in a monolayer. To test this prediction, they measured the surface areas of different mammalian erythrocytes microscopically.

It's not always easy to find historical photographs. In Grendel's case, we just couldn't find any photos of him. He served as Gorter's assistant, and we think that's worthy of photo representation. So, we put this one in its place.

The lipid bilayer is a thin polar membrane made of two layers of lipid molecules. These membranes are flat sheets that form a continuous barrier around cells. The cell membrane of almost all living organisms and many viruses are made of a lipid bilayer, as are the membranes surrounding the cell nucleus and other sub-cellular structures. The lipid bilayer is the barrier that keeps ions, proteins and other molecules where they are needed and prevents them from diffusing into areas where they should not be. Lipid bilayers are ideally suited to this role because, even though they are only a few nanometers in width, they are impermeable to most water-soluble (hydrophilic) molecules. Bilayers are particularly impermeable to ions, which allows cells to regulate salt concentrations and pH by pumping ions across their membranes using proteins called ion pumps.

For decades, researcher Mina Bissell pursued a revolutionary idea -- that a cancer cell doesn't automatically become a tumor, but rather, depends on surrounding cells (its microenvironment) for cues on how to develop. She shares the two key experiments that proved the prevailing wisdom about cancer growth was wrong.

Lesson Creator
New York, NY

Before you answer the question, watch Mina Bissell's TED Talk (linked in the Dig Deeper). If you find other resources, share them!

Feb 25 • 
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