Collagen

Question 1

What is the most abundant protein in the body?

Answer 1

Collagen

Question 2

What type of tissue contains collagen?

Answer 2

Connective tissue

• loose
• dense

Question 3

What are four examples of dense connective tissues that contain collagen?

Answer 3

Bone

Cartilage

Ligaments

Tendons

Question 4

What type of cell produces collagen?

Answer 4

Fibroblasts

Question 5

Which ribosomes produce collagen?

Answer 5

Ribosomes on the ER

Question 6

What form of collagen is produced by the ribosomes?

Answer 6

Preprocollagen

Question 7

What happens to preprocollagen in the ER?

Answer 7

Signal peptide is cleaved off to form procollagen

Hydroxylation

Triple helix formation

Question 8

What exactly in procollagen is hydroxylated in the ER?

Answer 8

Proline and lysine residues are hydroxylated

Question 9

What is the enzyme responsible for hydroxylation of procollagen in the ER?

Answer 9

Prolyl hydroxylase

Question 10

What does prolyl hydroxylase require in order to function?

Answer 10

Vit C

Fe2+ ions

Question 11

What is the importance of hydroxylation of procollagen?

Answer 11

Allows for increased hydrogen bonding between collagen chains in triple helix
increased stability of triple helix

Question 12

What is the disease caused by decreased stability of collagen triple helix?

Answer 12

Scurvy

Question 13

What type of triple helix does procollagen form?

Answer 13

Right-handed triple helix

Question 14

What is each collagen chain in the triple helix called?

Answer 14

Alpha chain

Question 15

How many collagen alpha chains form the triple helix?

Answer 15

Three duh

Question 16

What are the types of alpha chains that make up type 1 collagen triple helix?

Answer 16

Alpha-1 x2

Alpha-2

Question 17

What are the features of the triple helix of collagen?

Answer 17

Non-compressible

Non-extensible/high tensile strength

Question 18

What is the amino acid sequence of the collagen alpha chains?

Answer 18

Glycine-X-Y

X and Y tend to be proline or hydroxyproline

Question 19

Why is glycine repeated in the collagen alpha chains?

Answer 19

Only amino acid with small enough side chain to fit in the middle of the triple helix

Question 20

Where are procollagen triple helices transported to from the ER?

Answer 20

Golgi

Question 21

What happens to procollagen triple helices in the Golgi?

Answer 21

Packaged into vesicles

vesicles bud off from Golgi

Question 22

What happens to the vesicles containing procollagen triple helices?

Answer 22

Release their contents into the extracellular space by exocytosis

Question 23

What happens to procollagen triple helices in the cytoplasm?

Answer 23

N and C terminal peptides cleaved off

to form tropocollagen

Question 24

What happens to tropocollagen in the extracellular space?

Answer 24

Tropocollagen comes together to form collagen fibrils
then collagen fibres

cross-links formed between them

Question 25

What is responsible for forming cross-links between tropocollagen molecules?

Answer 25

Lysyl oxidase

Question 26

What does lysyl oxidase require to function?

Answer 26

Vit B6

Cu2+

Question 27

Why is tropocollagen formed extracellularly rather than inside the fibroblast?

Answer 27

Collagen fibres forming inside the fibroblast would damage and kill the fibroblast

Question 28

What type of tertiary structure does collagen have?

Answer 28

Fibrous tertiary structure