When a membrane is freeze-fractured, the bilayer splits down the middle between the two layers of phospholipids. In an electron micrograph of a freeze-fractured membrane, the bumps seen on the fractured surface of the membrane are
A) peripheral proteins.
B) phospholipids.
C) carbohydrates.
D) integral proteins.
E) cholesterol molecules.

Question

Quizplus · Accepted Answer

Integral proteins are embedded within the phospholipid bilayer and are responsible for creating channels and transporting molecules across the membrane. These proteins are the bumps seen on the fractured surface of the membrane in an electron micrograph. Peripheral proteins are located on the surface of the membrane and would not be split during freeze-fracturing. Phospholipids, carbohydrates, and cholesterol molecules are all components of the membrane but would not be visible as bumps in a freeze-fractured electron micrograph.

When a Membrane Is Freeze-Fractured, the Bilayer Splits Down the Middle