Session 9-Collagen Flashcards Preview

Semester 1-MCBG > Session 9-Collagen > Flashcards

Flashcards in Session 9-Collagen Deck (15):
1

What is the basic unit of collagen?

Tropocollagen

2

Which AA is in every third position along each alpha chain?

Glycine

3

How many alpha chains is collagen made from?

Three

4

What are the characteristics of the triple helix that forms collagen? (4)

1. Made up of alpha chains but not an alpha helix
2. Non-extensible
3. Non-compressible
4. High tensile strength

5

Why is glycine so abundant in collagen?

Glycine is the only AA with a small enough side chain to fit in the middle of the helix on the inside

6

Each alpha chain has this repeat: (Gly-X-Y)n.
Which AA are usually found in the X and Y positions?

Proline or hydroxyproline (hydroxyproline is not part of the 20 AA, it is formed when Pro is hydroxylated)

7

Which bonds are found between alpha chains and what do they do?

Hydrogen bonds stabilise the structure

8

How many types of collagen are there?

28

9

What is the 1) molecular formula of type I collagen and 2) what is its tissue distribution?

1) Alpha1 (I)2 alpha2 (I)
2) skin
Tendon/ligaments
Bone
90% of all body collagen

10

What is the 1) molecular formula of type II collagen and 2) what is its tissue distribution?

1) alpha1(II)3
2) Cartilage
Intervertebral discs

11

What is the 1) molecular formula of type III collagen and 2) what is its tissue distribution?

1) alpha1(III)3
2) foetal skin
Cardiovascular system

12

What is the 1) molecular formula of type IV collagen and 2) what is its tissue distribution?

1) alpha1(IV)2 alpha2(IV)
2) basement membrane

13

Why is tropocollagen secreted before final processing occurs?

Collagen is large so the cell would burst
Peptidases are only activated outside the cell

14

What causes scurvy?

Weak tropocollagen triple helices due to less vitamin C in the diet so hydrogen bonds cannot form

15

What does CHADPOGRL stand for?

Cleavage of signal peptides
Hydroxylation of proline and lysine
Addition of N-linked oligosaccharide and galactose (in ER)
Disulphide bridge formation
Procollagen (sent to golgi)
O-linked glycosylation (in golgi)
Golgi-exocytosis as tropocollagen
Removal of N/C terminal peptides (procollagen peptidase)
Lateral aggregation to form fibrils