Growth Factors

Question 1

What are growth factors?

Answer 1

Polypeptides that act on cell surface receptors

They are local hormones

Question 2

What gene codes for the growth factors?

Answer 2

Proto-oncogene

Question 3

How do growth factors cause cell division?

Answer 3

Bind to specific receptors

Stimulate transcription of genes that regulate entry of cell into cell cycle and cell’s passage through it

Question 4

Apart from cell proliferation, what other effects can growth factors have?

Answer 4

Inhibition of division 
Locomotion
Contractility 
Differentiation
Viability
Activation 
Angiogenesis

Question 5

Give some examples of growth factors? What produces GFs?

Answer 5

Epidermal growth factor
Vascular endothelial GF
Platelet derived GF
Tumour necrosis GF

Platelets, macrophages, endothelial cells etc

Question 6

What is contact inhibition?

Answer 6

The process by which cells stop proliferating and moving once they are in contact with other cells

Question 7

Where might you find cells with no contact inhibition?

Answer 7

In tumours, malignant cells

Question 8

How does contact inhibition work? How do cells know when they’re surrounded?

Answer 8

There is signalling through adhesion molecules.

Cadherins bind cells to each other

And intergrins bind cells to extracellular matrix