Synthesis of Collagen

Question 1

What is the basic unit that makes collagen?

Answer 1

Tropocollagen

Question 2

What is the structure of tropocollagen?

Answer 2

3 polypeptide chains (alpha)
triple helix
Glycine in every 3rd position of the chain
Hydrogen bonds between the alpha chains stabilises structure.

Question 3

What are the properties of a triple helix?

Answer 3

High tensile strength
non compressible
Non extensible

Question 4

What secretes collagen?

Answer 4

Fibroblasts

Question 5

Where can you find collagen?

Answer 5

In connective tissue

Question 6

Where is collagen made?

Answer 6

Lumen of ER

Question 7

What chemical structural changes does the collagen precurser (preprocollagen) go through when in the ER lumen?

Answer 7

Cleavage of signal peptidase
Hydroxylation
Addition of N linked oligosaccharides
Addition of Galactose
Formation of disulphide bonds
Forms alpha helix (procollagen)

Question 8

Where does Procollagen made in the ER lumen go to next?

Answer 8

The Golgi body where glucose is added

Question 9

What happens to procollagen once it has been released from the Golgi body?

Answer 9

It is in a vesicle that undergoes exocytosis out of the cell.

Question 10

What happens to procollagen once it has been released from the cell?

Answer 10

The N and C terminal propeptides are released (Now called Tropocollagen)

Question 11

What happens once Tropocollagen is formed?

Answer 11

Collagen molecules associate and form cross links, then the fibrils aggregate to form a collagen fibre