AP Bio Insta-Review Topic 2.4: Plasma Membranes

Front

What is the main component of the cell membrane?

Back

Phospholipids are the main component of the cell membrane, forming a bilayer that provides structure and regulates the movement of substances in and out of the cell.

Front

What is the orientation of phospholipids in the plasma membrane?

Back

Phospholipids are oriented in a double layer, with fatty acid tails facing inward (toward each other) and phosphate heads facing outward (toward the exterior and interior of the cell).

Front

What role does cholesterol play in the plasma membrane?

Back

Cholesterol helps to stabilize the fluidity of the plasma membrane, making it less permeable to very small water-soluble molecules that might otherwise pass freely through.

Front

What types of materials can easily pass through the plasma membrane?

Back

Small, nonpolar molecules can easily pass through the plasma membrane due to their ability to diffuse through the lipid bilayer.

Front

What is a transmembrane protein?

Back

A transmembrane protein is a type of membrane protein that spans the entire lipid bilayer, with parts exposed on both the inside and outside of the cell.

Front

What is the function of peripheral proteins in the plasma membrane?

Back

Peripheral proteins are located on the surface of the membrane and play roles in signaling, maintaining the cell's shape, and facilitating communication between cells.

Front

How do polar molecules interact with the plasma membrane?

Back

Polar molecules generally cannot pass through the lipid bilayer easily and often require specific transport proteins to facilitate their movement across the membrane.

Front

What is the fluid mosaic model?

Back

The fluid mosaic model describes the structure of the plasma membrane as a mosaic of various proteins that float in or on the fluid lipid bilayer, allowing for flexibility and movement.

Front

What is the significance of the hydrophobic and hydrophilic regions of phospholipids?

Back

The hydrophobic (water-repelling) fatty acid tails face inward, while the hydrophilic (water-attracting) phosphate heads face outward, creating a barrier that separates the cell from its environment.

Front

What is selective permeability in the context of the plasma membrane?

Back

Selective permeability refers to the ability of the plasma membrane to allow certain substances to pass while restricting others, thus maintaining homeostasis within the cell.