Items 16-22
Match each numbered biochemical description of collagen with the most appropriate lettered collagen type.
(A) Type I collagen
(B) Type II collagen
(C) Type III collagen
(D) Type IV collagen
(E) Type V collagen
(G) Type VI collagen
(H) Type VII collagen
(I) Type VIII collagen
(J) Type IX collagen
(K) Type X collagen
16. This type of collagen is abundant in hyaline cartilage. It contains three identical a chains.
17. This type of collagen is abundant in bone, the dermis, and tendons. It contains two different a chains.
18. This type of collagen is the most abundant type in basement membranes.
19. This type of collagen is rich in carbohydrate. It is abundant on the cell surface of many cell types.
20. This type of collagen is abundant around blood vessels and smooth muscle in the gastrointestinal tract. It contains three identical a chains.
21. This type collagen forms fibrils involved in anchoring basement membranes to underlying connective tissue. It contains three identical a chains.
22. This type of collagen is abundant in cartilage. It contains three different a chains.
ANSWERS AND TUTORIAL ON ITEMS 16-22
The answer are: 16-B;17-A;18-D;19-E-20-C;21-G;22-I. Collagen is the major extracellular protein of most connective tissue. It is secreted by fibroblasts as well as other cell types and occurs as a large number of molecular variant types, each designated by a specific Roman numeral. Each collagen type consists of three intertwined helical a chains. There are three major different types of a chains (designated a1 to a3) and several minor variants of each of these, based on slight differences in amino acid composition. Different collagen types consist of different combinations of a chains.
Types I collagen (A) is widely distributed in the body. It is most abundant in bone, skin, tendons, and dentin. It forms large striated fibrils and is composed of two a1(I) and on a2(I) chains.
Types II collagen (B) is most abundant in hyaline cartilage. It is also present in the vitreous body of the eye and the nucleus pulposus of intervertebral disc. It is composed of three a1 (II) chains.
Type III collagen (C) is also widely distributed, like Type I collagen, but is not abundant in bone. It is abundant in fetal skin and surrounding many smooth muscle cells. Type III collagen is also abundant in reticular fibers. It forms small diameter striated fibrils and is composed of three a (III) chains.
Type IV collagen (D) is abundant in basement membranes in many locations, e.g., the glomerular basement membrane and surrounding the lens. If forms an anastomosing network of fibrils without striations and is composed of two a1(IV) and one a2(IV) chains.
Type V collagen (E) is widely distributed like Type I collagen but does nor form striated fibrils.Instead, it thin, nonbanded layers around cells. It is prominent in muscle and tendon sheaths. It is composed of two a1(V) and one a2(V) chains.
Type VI collagen (F) is a minor collagen type with wide distribution.It forms fibrils with striations of 100 nm periodicity. It is composed of two a1(VI) and one a2(VI) chains.
Type VII collagen (G) is widely distributed just beneath many epithelial basement membranes. It forms fibrils that help anchor basement membranes to underlying connective tissue structures. It is composed of three a1(VII) chains.
Type VIII collagen (H) is found surrounding endothelial cells of blood vessels and in the cornea. It is composed of three a1(VIII) chains.
Type IX collagen (I), like Type II collagen, is found in cartilage. It is associated with chondroitin sulfate and its fibrillar form is poorly understood. It is composed of one a1(IX), one a2(IX), and one a3(IX) chains.
Type X collagen (J) is restricted to the zone of hypertrophy of developing bones. It is composed of three a1(X) helices. Dual Arm type of microscope Boom Mounted Microscopes with Mobile Floor Stand Boom Mounted Microscopes.
