16 . Cell Communication

1. 16. Cell Communication Essential cell biology 533-572

2. Fig.1: Yeast cells respond to mating factor Fig.2: Signal transduction is the process whereby one type of signal is converted to another.

3. Fig.3: Animal cells can signal to one another in various ways.

4. Fig.4: Contact dependent signaling controls nerve-cell production.

5. Tab.1: Some examples of signal molecules Hormones Adrenalin increases blood pressure, heart rate, and metabolism Site of origin: adrenal gland Derivative of the aminoacid tyrosine

6. Local mediators Epidermal growth factor (EGF) stimulates epidermal and many other cell types to proliferate Site of origin: various cells Protein

7. Neurotransmitters Acetylcholine excitatory neurotransmitter at many nerve-muscle synapses and in central nervous system Site of origin: nerve terminals Derivate of cholin

8. Contact-dependent signal molecules Delta inhibits neighboring cells from becomming specialized in a same way as the signaling cell

9. Fig.5: The same signal molecule can influence different responses in diffrent target cells. Fig.6: An animal cell depends on multiple extracellular signals.

10. Fig.7: Extracellular signals alter the activity of a variety of cell proteins to change the behavior of the cell. Fig.8: Cellular signaling cascades can follow a complex path.

11. Fig.9: Extracellular signal molecules bind either to cell-surface receptors or to intracellular enzymes or receptor. intra extra

12. Fig.10: Nitric oxide (NO) triggers smooth muscle relaxation in a blood-vessel wall.

13. Fig.11: Some small hydrophobic hormones bind ti intracellular receptors that act as gene regulatory proteins. testosteron

14. Fig.12: The steroid hormone cortisol acts by activating a gene regulatory protein.

15. Fig.13: Most signal molecules bind to receptor proteins on the target cell surface. Human growth hormon Receprot proteins Plasma membrane

16. Fig.14: Cell-surface receptors fall into three basic clasess.

17. Fig.15: Many Intercellular signaling proteins act as molecular switches

18. Fig.17: G proteins dissociate into two signaling proteins when activated. Fig.16: All G-protein-linked receptors possess a similar structure.

19. Fig.18: The G-protein a submit switches itself off by hydrolizing its bound GTP.