Extracellular matrix

Question 1

How much of our body is cell?

Answer 1

50%

Question 2

What are examples of specialised ECM (extracellular matrix)?

Answer 2

bone (calcified)
hair (fibrous & loose)
tendons (tensile strength)
cornea (transparent)
skin (elastin)

Question 3

What does the extracellular matrix regulate?

Answer 3

• Migration (cell migration)
• Tissue integrity & cell shape
• Proliferation (cell growth)
• Differentiation

Question 4

What does the collagen fibre provide?

Answer 4

Provides strength

Question 5

What does the elastic fibre provide?

Answer 5

Provides pliability

Question 6

What are 2 examples of fibrous proteins?

Answer 6

• collagens
• elastin

Question 7

What are 2 examples of adhesion proteins?

Answer 7

• fibronectin
• laminin

Question 8

What is one of the most abundant proteins in the body?

Answer 8

Collagen

Question 9

How many variants of collagen are there?

Answer 9

20-40 variants - different functions but highly conserved

Question 10

Describe the structure of collagen

Answer 10

• Triple Helix
• 3 alpha chains
• produced by fibroblasts & epithelial cells

Question 11

What are 3 examples of collagen defects?

Answer 11

• Ehlers-danios syndrome
• Vascular form
• Arterial rupture

Question 12

What % of the dry weight of aorta is elastin?

Answer 12

Elastin

Question 13

What is tropoelastin converted to, in the presence of lysyl oxidase?

Answer 13

elastin

Question 14

Where can fibrilin (elastin laid over microfibril scaffold of fibrillin) be found?

Answer 14

Bones & eyes

Question 15

Is a glycosaminogylcan (GAG) charged?

Answer 15

Highly charged

Question 16

What has a higher % of sugar - proteogylcan or glycoprotein?

Answer 16

proteoglycan (95%), over glycoprotein (60%)

Question 17

Where are adhesion glycoproteins (laminins) present?

Answer 17

between epithelium & basal lamina

Question 18

How does fibronectin bind to matrix?

Answer 18

through divalent cations. removal of cations causes cells to detach

Question 19

What is a component of a focal adhesion?

Answer 19

transmembrane receptors (integrins), which is connected to the cytoskeleton and is involved in signalling. Talin binds to the integrin.

Question 20

What is the consequence of the knockout of beta 1 integrin?

Answer 20

embryonic lethal at implantation (Day 5)

Question 21

What is the consequence of the knockout of alpha 5 integrin?

Answer 21

embryonic lethal mesoderm development (Day 10)

Question 22

What is the consequence of the knockout of AiibB3 integrin?

Answer 22

bleeding gums & nose bleeds

Question 23

What is the consequence of the knockout of B2 integrin?

Answer 23

• leukocytes adhesion deficiency (LAD) syndrome
• impaired expression
• recurrent bacterial infections