extracellular matrix

Question 1

fibrillar collagen location

Answer 1

abundant in bone, tendon and skin

Question 2

fibrillar collagen properties

Answer 2

fibrous, inelastic, high tensile strength

Question 3

how do fibrillar collagens exhibit high tensile strength

Answer 3

staggered array; successive layers formed ar right angles so resist force in all directions

Question 4

structure of fibrillar collagen

Answer 4

3 a chains in a left-handed stiff triple helix: glycine (small)-x (proline)-y (hydroxyproline)

Question 5

type I a chain structure

Answer 5

2 same chain, 1 different chain

Question 6

type II and III a chain structure

Answer 6

all same a chain

Question 7

a chain to collagen fibre

Answer 7

IC: a chain → triple helix → EC: collagen fibril → collagen fibre

Question 8

fibrillar collagen biosynthesis: precursor, location, process

Answer 8

synthesised from procollagen in endoplasmic reticulum by hydroxylation

Question 9

process of fibrillar collagen biosynthesis

Answer 9

procollagen (N and C-terminal propeptides not present in triple helices) → collagen (N and C-terminals removed EC) → fibrils (cross-linking)

Question 10

what does hydroxylation contribute to

Answer 10

interchain hydrogen bonding, modifying covalent cross-links

Question 11

what enzymes catalyse hydroxylation

Answer 11

polyl and lysyl hydroxylases

Question 12

what prosthetic groups do these enzymes require

Answer 12

vitamin C and Fe2+

Question 13

consequences of absence of these prosthetic groups

Answer 13

tissue instability leading to scurvy

Question 14

fibril-associated collagen: type IX and XIII function

Answer 14

regulate fibril organisation and size

Question 15

fibril-associated collagen: type IV function

Answer 15

forms sheet-like network in basal lamina