Fluid Mosaic Model

What is the function of the cell membrane?

• → It separates the cell’s interior from the external environment and regulates what enters and exits.

• Example: It prevents ions like Na⁺ from freely entering but allows lipid-soluble vitamins through.

What is the phospholipid bilayer?

• → A double layer of phospholipids that forms the cell membrane.
  Example: The bilayer is fluid, allowing proteins to move around.

What is the fluid mosaic model?

• → A model describing the membrane as fluid, where phospholipids and proteins move laterally.

  
  Example: Membrane proteins shift positions, making the cell flexible.

What is the role of cholesterol in the membrane?

• → It regulates membrane fluidity by reducing fluidity at high temperatures and preventing freezing at low temperatures.

  
  Example: Animal cell membranes contain cholesterol to stabilize their structure.

What are integral membrane proteins?

Integral membrane proteins are permanent proteins that are embedded in the cell membrane. They help the cell interact with its surroundings.

What Do They Do?

• They span the membrane (go through it).

• They act as channels, transporters, or receptors to help substances move in and out of the cell.

Example: Ion channels that allow Na⁺ to enter neurons

What are peripheral membrane proteins?

→ Temporary proteins that attach to the membrane or integral proteins for signaling and structural functions.

Peripheral membrane proteins are temporary proteins that attach to the surface of the membrane or to integral proteins. Unlike integral membrane proteins, they do not span the entire membrane.

Key Features:

• They attach temporarily to the inner or outer surface of the membrane.

• They help with signaling and structural functions.

• They can detach and reattach when needed
  Example: Enzymes that help speed up reactions near the membrane.

What is the function of glycoproteins?

• → They have carbohydrate chains that provide structural support, cell recognition, and interaction.

  
  Example: Immune system cells use glycoproteins to recognize foreign invaders.

What are glycolipids?

→ Carbohydrate chains attached to phospholipids that assist in cell recognition and communication.

Example: Glycolipids help red blood cells determine blood type.