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BIO120H1 (1,000)
Lecture

Notes taken during lecture


Department
Biology
Course Code
BIO120H1
Professor
Jean Jiang Nash

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LECTURE 10
Cell communication
Unicellular organism
Signal transduction cascade
EGF receptor is the receptor tyrosine kinase
Feeds into nucleus to alter transcription
A NETWORK not linear
Why is signalling important?
Cyclic AMP
oNucleotide secreted by single celled organism, slime mold
In rotting log in forest
Divide and take over the log
Eventually run out of nutrients, secrete cyclic AMP
Cyclic AMP attracts each other, so all mold gets together into a
slug and move out of wood
This organism is at the edge of unicellular and multicellular
Two types of cells stalk and spores spore flies away stalk dies
Get together because they’re attracted to cAMP
Cell migrates towards the source outside the cell
Cell receives cAMP, activates PI-3 kinase
oActin polymerases and pseudopods pushes out, so movement
Signal molecules and receptors
Hydrophilic ligands
oCan move around in extrcelluar fluid
oOr secreted from one cell and move by diffusion to another
Hydrophoblic signalling molecules
oEg. Glucocorticoid
Classes of cell surface receptors in animals
E.g. visual, taste, smell receptors
Cytosolic domain has enzymatic activity or is associated with an enzyme
Or associated with an enzyme
o(see the figure 15-16)
Built into receptor or not built into receptor
Important roles in animal development
oExtremely important
oSpecifying cell types
Roles in development, growth, disease resistance
Receptors for plant hormones
Intracellular signalling pathways
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