What is the structure and appearance of a cell membrane?

The cell membrane is a thin, flexible barrier that surrounds the cell. It is made up of a double layer of phospholipid molecules with proteins embedded throughout. This structure gives the cell membrane its fluidity and allows it to regulate the passage of substances in and out of the cell. The cell membrane also contains cholesterol molecules that help maintain its stability and integrity. Overall, the cell membrane has a semi-permeable nature, meaning it selectively allows certain substances to pass through while blocking others.