1. signal transduction
Cell-cell contact
via gap junctions or plasmodesmata;
signal molecule passes between cells
Cell-cell recognition
molecule binds to specific receptor;
“receptor-ligand interaction”

3. When the ligand binds, other molecules are
produced within the cell
“second messengers” relay the signal from
interior of cell
May trigger cell activity and/or gene expression

4. Things that can trigger cell signaling
G-protein-linked receptors
tyrosine kinase receptors
ion-channels

7. Many different types of G proteins can interact
with different cellular proteins
Vision
Smell
Acetylcholine receptors: one “family” are ion
channels (contraction), another are
G protein receptors (relaxation)
Developmental pathways
What does G protein activation accomplish?
Activation of second messenger system
cAMP
calcium
Levels are elevated

8. Several families of tyrosine kinases

10. Na channel

11. Photoreceptor – rods and cone

15. Taste
Five different groups:
Sweet
Salty
Bitter
Sour
Umami
The different tastes can be caused by ion channels,
receptor proteins and other signal pathways

16. Use your receptors to smell and taste things!