AP BIOLOGY

Detailed explanation-1: -The cell membrane is a thin, flexible barrier that separates the cell from the environment. Also known as the plasma membrane, the cell membrane is made of two layers of phospholipids, called a phospholipid bilayer. Phospholipids are amphipathic lipids. This means they have both hydrophilic and hydrophobic parts.

Detailed explanation-2: -Cell Membrane (Plasma Membrane) The cell membrane, also called the plasma membrane, is found in all cells and separates the interior of the cell from the outside environment. The cell membrane consists of a lipid bilayer that is semipermeable.

Detailed explanation-3: -In water, phospholipids spontaneously form a double layer called a lipid bilayer in which the hydrophobic tails of phospholipid molecules are sandwiched between two layers of hydrophilic heads (see figure below).

Detailed explanation-4: -Only small uncharged molecules can diffuse freely through phospholipid bilayers (Figure 2.49). Small nonpolar molecules, such as O2 and CO2, are soluble in the lipid bilayer and therefore can readily cross cell membranes.

Detailed explanation-5: -The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules. These membranes are flat sheets that form a continuous barrier around all cells.