Cell Communication Flashcards
Direct Communication
Cell Junctions (Usually gap junctions- directly connects cytoplasms)
Indirect Communication
Chemical Messengers (e.g. yeast mating)
Communication via Surface Molecules
Cell Recognition (e.g. immune response, antibody/antigens)
Chemical Signalling
Local or long distance
Local regulators or hormones
Convert signals on cells surface into cellular responses
Local Regulators
Paracrine
Example- Interferon- tells other cells their next door neighbour is sick
Long Distance Signalling
Hormones- don’t need a lot of messengers, the effect grows exponentially (one first messenger activates many, many products)
Signal Transduction
Reception-Transduction- Response
Reception of Signal Transduction
Brings in signal
Signal molecule binds to receptor protein
Membrane or intracellular
Binding highly specific
Intracellular Receptor
Receptor proteins are cytoplasmic or nuclear
Signal molecules are small or hydrophobic
Example- Steroids (testosterone)
Membrane Receptors
G-Protein linked receptors
Tyrosine Kinases
Ion Channel
Transduction of Signal Transduction
Relay signals from receptors to target molecules
Multi-step - Control, amplifies signal
Phosphorylation Cascade- one activates the next , which activates the next, etc
Second Messengers
Small non-protein molecules or ions
cAMP
Cyclic AMP
Second messenger
Made from ATP, uses G-proteins
Activates protein kinase
Rapid amplification
Calcium
Important second messenger
Regulated in cytosol, stored in SER
Activated IP3 releases calcium from ER
DAG and IP3 activates enzymes
Calmodulin
Protein 2nd messenger
Similar to cAMP response
activates protein kinase
