Collagen

Question 1

What is the most abundant protein in the body?

Answer 1

Collagen

Question 2

What is the structure of collagen?

Answer 2

Three alpha chains
wind around each other to give a triple helix
come together to form microfibrils
come together to form fibrils
come together to form fibres

Question 3

Which types of collagen are the “fibrillar” ones?

Answer 3

Types 1-3

Question 4

What is the role of the fibrillar collagens?

Answer 4

Give strength to tissues

Question 5

Which types of collagen are the “amorphous” ones?

Answer 5

Types 4-6

Question 6

What is the most common type of collagen in the body?

Answer 6

Type 1

Question 7

Where is type 1 collagen found in the body?

Answer 7

Hard tissues - bone

Soft tissues - tendons, ligaments, skin, blood vessels, hollow organs, sclera

Question 8

Where is type 4 collagen found?

Answer 8

Basement membrane

Question 9

What secretes type 4 collagen in the basement membrane?

Answer 9

Epithelial cells

Question 10

How long does collagen synthesis take?

Answer 10

1-2 hours

Question 11

What enzyme is responsible for collagen remodelling?

Answer 11

Collagenase

Question 12

Give an example of an acquired disease due to defective collagen synthesis

Answer 12

Scurvy

Question 13

Give examples of three inherited diseases due to defective collagen synthesis

Answer 13

Ehler’s Danlos syndrome
Osteogenesis imperfecta
Alport syndrome

Question 14

What is the cause of scurvy?

Answer 14

Vitamin C deficiency

Question 15

How does vitamin C deficiency affect collagen synthesis?

Answer 15

Reduced hydroxylation of procollagen alpha chains

Question 16

How does vitamin C deficiency affect the strength of collagen?

Answer 16

Reduced cross-linking between chains, microfibrils, fibrils

weaker collagen

Question 17

Collagen in ……………………. is particularly affected

Answer 17

Blood vessels

Question 18

What are the symptoms of scurvy?

Answer 18

Porlonged bleeding
Tooth loss
Old scars becoming fresh wounds

Question 19

Why does prolonged bleeding occur with scurvy?

Answer 19

Unale to heal wounds

Question 20

Why does tooth loss occur with scurvy?

Answer 20

Collagen in perodontal ligament has short half-life

replaced by defective collagen

Question 21

Why do old scars open up as fresh wounds with scurvy?

Answer 21

High collagen turnover in scars for 2 years after their formation
replaced by defective collagen

Question 22

What is the cause of Ehler’s Danlos syndrome?

Answer 22

Defective conversion of procollagen to tropocollagen

Question 23

How are collagen fibres different in Ehler’s Danlos syndrome?

Answer 23

Lack tensile strength, are weak

Question 24

What are the features of skin in Ehler’s Danlos syndrome?

Answer 24

Hyperextensible, recoils
Thin
Fragile
Susceptible to injury

Question 25

Why is the skin hyperextensible?

Answer 25

Elastin fibres stretch a lot, not held in check by tethering effect of collagen then recoil

Question 26

What are the features of joints in Ehler's Danlos syndrome?

Answer 26

Hypermobile | Predisposed to dislocation

Question 27

What are the complications of Ehler's Danlos syndrome?

Answer 27

Rupture of colon large arteries cornea Retinal detachment

Question 28

What is the cause of osteogenesis imperfecta?

Answer 28

Lack fo type 1 collagen

Question 29

What are the features of osteogenesis imperfecta?

Answer 29

``` Fragile bones Deformation of bones - progressive, severe Blue sclera Dental abnormalities Hearing impairment ```

Question 30

Why are bones fragile and deformed in osteogenesis imperfecta?

Answer 30

Lack of bone tissue cannot withstand mechanical stress break easily, deformed easily

Question 31

Why is the sclera blue with osteogenesis imperfecta?

Answer 31

Lack of collagen within | so it's translucent

Question 32

Which chromosome is faulty in Alport syndrome?

Answer 32

X chromosome

Question 33

Which gender is more commonly affected by Alport syndrome?

Answer 33

Males

Question 34

What is the cause of Alport syndrome?

Answer 34

Defective type 4 collagen

Question 35

How do people with Alport syndrome present?

Answer 35

Haematuria when children | Renal failure as adults

Question 36

What are the features of Alport syndrome?

Answer 36

Dysfunction of glomerular basement membrane lens of eye cochlea of ear

Question 37

What can the dysfunctional glomerular basement membrane lead to?

Answer 37

Kidney failure

Question 38

What can the dysfunctional lens of the eye lead to?

Answer 38

Eye disorders

Question 39

What can the dysfunctional cochlea of the ear lead to?

Answer 39

Neural deafness