Which of the following describes the primary components of the extracellular matrix?

• A. Only carbohydrates and lipids
• B. Proteins, glycoproteins, and proteoglycans
• C. Enzymes and nucleic acids
• D. Only fibers and water

Answer: (B)

The primary components of the extracellular matrix (ECM) include proteins, glycoproteins, and proteoglycans. The ECM is a complex network that provides structural and biochemical support to surrounding cells, and these components play crucial roles in its function.

Proteins form the fibrillar backbone of the matrix. For instance, collagen is the most abundant protein in the ECM and provides tensile strength. Glycoproteins, such as fibronectin and laminin, assist in cell adhesion and signaling, facilitating the interaction between cells and the ECM. Proteoglycans are composed of a core protein and glycosaminoglycan (GAG) chains, contributing to the gel-like consistency of the matrix and playing a role in cell signaling and hydration.

Other options do not accurately reflect the composition of the ECM. While carbohydrates are involved in the structure, lipids, enzymes, and nucleic acids do not characterize the primary components of the ECM. Specifically, enzymes do not form part of the ECM but may act on ECM components, and nucleic acids are not structural components of the matrix. Furthermore, while fibers and water are present, they do not encompass the full range of critical components that contribute to the functionality of the ECM.