1. Phospholipids: These are the primary building blocks of the membrane. They have a unique structure with a hydrophilic (water-loving) head and a hydrophobic (water-fearing) tail. This allows them to form a bilayer, with the heads facing outwards towards the watery environment both inside and outside the cell, and the tails tucked in between, creating a barrier.
2. Proteins: These molecules are embedded within the phospholipid bilayer, serving various functions like:
* Transport proteins: Help move molecules across the membrane.
* Receptor proteins: Bind to signaling molecules and trigger responses inside the cell.
* Enzymes: Catalyze reactions within the membrane.
* Structural proteins: Give the membrane shape and support.
While these two are the most prevalent, other molecules like cholesterol can also be found in the cell membrane, contributing to its fluidity and stability.
