Ch' 11

1
Ch. 11

• Cell Communication

2
Types of signals received by cells

• Electromagnetic signals
• Eg. light
• Mechanical signals
• Eg. Touch/pressure
• Chemical signals
• Hormones, neurotransmitters

3
Chemical Signals

• Paracrine signaling
• Local
• Growth factors, inflammatory chemical mediators
• Synaptic signaling
• Local
• neurotransmitters
• Endocrine signaling
• Distant
• Eg. Ethylene, testosterone
• Direct contact
• Cell junctions
• Gap junctions
• Plasmodesmata
• Eg. Immune system, embryonic development

4
Sutherlands observations (Nobel prize winner in
1971)

• Epi ? activates glycogen phosphorylase
• Glycogen ? G6P ? glucose

Epi Liver cells
Epi glycogen Phosphorylase glycogen
G6P ? Glucose
No G6P nor glucose
5
Major steps of cell signaling

• 1. Reception
• 2. Transduction
• Signal-transduction pathway
• 3. Response

6
Ligand-receptor interactions

• Lock and key
• Receptor changes shape
• It can then interact with another molecule.