Question

Proteoglycans in the extracellular matrix of animal tissues

(a) provide tensile strength.

(b) form a dense compact matrix.

(c) are linked to microtubules through the plasma membrane.

(d) are polysaccharides composed of glucose subunits.

(e) provide cartilage with the ability to resist compression.

Answer 1

Answer: Proteoglycans in the extracellular matrix of animal tissues

(a) provide tensile strength.

-> Proteoglycans allow connective tissues of the Extracellular Matrix (ECM) to be able to withstand compressional forces through hydration and swelling pressure to the tissue.

(b) form a dense compact matrix.

->Proteoglycans are either secreted into the ECM or linked to the cell surface in the form of syndecans and glypicans.

(c) are linked to microtubules through the plasma membrane.

->A network of collagen fibers and proteoglycans is found outside of the cell. Collagen connects to integrin proteins in the plasma membrane via fibronectin. On the inside of the cell, the integrins link up to the microfilaments of the cytoskeleton. Integrins anchor the cell to the extracellular matrix.

(d) Are polysaccharides composed of glucose subunits?

-> Two d-glucose residues are joined by a glycosidic linkage in Proteoglycans.

(e) Provide cartilage with the ability to resist compression.

Cartilage proteoglycans:  provides cartilage with its osmotic properties, which give articular cartilage its ability to resist compressive loads.