Elastic cartilage and most hyaline cartilages are surrounded by a protective sheath called a:.

Perichondrium

Explanation:

Elastic cartilage (like hyaline cartilage) has chondrocytes located in lacunae and the tissue is surrounded by a perichondrium. The perichondrium (Figure 7–2) is a sheath of dense connective tissue that surrounds cartilage in most places, forming an interface between the cartilage and the tissues supported by the cartilage. The perichondrium harbors the blood supply serving the cartilage and a small neural component. Articular cartilage, which covers the ends of bones in movable joints and which erodes in the course of arthritic degeneration, lacks perichondrium.

. ph changes the ability of them he enzyme to dissolve in water.

it marks things for degradation via the proteasome. it alters there celluar location.