Final answer:
The ECM contains three major classes of molecules: collagens, providing structural support; proteoglycans, filling spaces and regulating molecule movement; and fibronectin, assisting cell adhesion to collagen.
Step-by-step explanation:
The three classes of molecules found in the extracellular matrix (ECM) are:
- Collagens: These proteins form a large part of the ECM and provide strength and structure. They are found in various tissues, including skin, bone, tendon, and cartilage.
- Proteoglycans: These are carbohydrate-protein complexes that form a gel-like substance in the ECM, filling the spaces between cells and fibres, and playing a role in the regulation of the movement of molecules through the matrix.
- Fibronectin: This is a glycoprotein that helps cells adhere to the collagen fibres, playing a critical role in wound healing and other cellular functions that involve the ECM.
The ECM is not only essential for providing structural support to tissues but also facilitates communication between cells, contributing to tissue maintenance and repair.