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Cell Biology - Class 03
The in-depth study of human cells
By: David Botton

Signals


Signals

external signals

chemical

hormones

nerotransimtters

growth factors

cell messengers

electrical

light

mechanical

Definition

ability for cells to communicate across body

New-Branch

applies to all cells in body

signal transduction

= process of transmission from ligand to affect DNA

1. Receptor recognition of ligand

2. Transduction = extracellular message becomes intracellular message

secondary messenger

potentially can be amplified to many messengers

allows for specificity and diversity

ie. same receptor different possible messengers and so responces

3. Transmission

secondary messenger must reach effector

4. Modulation of effector

by activating protein kinase (adds phosphors to proteins)

or activation of phophatases (removes phosphors from proteins)

5. Responds to initial stimulus

6. Termination of responce

pathways

gap junctions

protein cylinder

allows electrical or chemical passing (in particular Ca)

direct cell to cell conduits

cardiac and smooth muscles primary sites

allows for quick signal transport

see types in book

excretion to receptor

excretion to receptor to signal transduction

purpose

adapt to changes in environment

coordinate actions between cells

(c) 2005 All Rights Reserved - David Botton