cell signalling

Question 1

What are growth factors

Answer 1

proteins/peptides that bind to cell surface receptors to induce
- cells to enter the cell cycle
- changes in gene expression
- cell migration

Question 2

what receptors can growth factors bind to

Answer 2

protein kinases - that phosphorylate serine, threonine or tyrosine amino acids

Question 3

How can cancer change receptors

Answer 3

can increase receptor number and activity

Question 4

How does the epidermal growth factor cause cell division

Answer 4

1. binds to kinase linked receptor
2. the two inactive monomers in tyrosine kinase forming an active dimer
3. cross phosphorylation the tyrosine kinase domains occurs
4. phosphorylated tyrosine’s recruit proteins on SH2 domains.
5. These proteins have SH3 domains on their termini which bind to other proteins - transmitting signals to the nucleus.
6. This causes cell growth and the cell cycle (moving from G0 -> G1)

Question 5

What receptors are involved in cell migration

Answer 5

g-coupled receptors or tyrosine kinase

Question 6

What is chemotaxis

Answer 6

• the cell sense of direction during cell migration
• enabled by the cell moving up the growth factor concentration gradient

Question 7

What is the mechanism of cell migration

Answer 7

• receptors at ‘front’ (direction of movement) are stimulated by growth factors
• lamellipodium elongate by actin polymerisation
• contraction at the back of the cell mediated by myosin 2 filaments that interact with the actin filaments
• focal points are attachments to the substratum which cause traction and detach and reattach as the cell moves forwards

Question 8

How can cancer affect cell migration

Answer 8

cancer cells can migrate once progressed to a certain level