Transduction, feedback, + communication Flashcards
What is signal transduction?
The process ofconverting a signal into a cellular response
Where did cell signaling pathways first evolve
Early unicellular eukaryotes and prokaryotes
Three stages of transduction
Reception, transduction, response
What is reception
Cell detection of signal
Ligand
Small molecule that specifically binds to larger ones (serves as first messenger)
Where does the ligand bind
Receptor protein of target cell
Ligand binding generally causes…
A receptor protein to change shape which triggers transduction
Signaling molecules inside the cell are
Small, non-polar
Signaling molecules on the cell membrane are
Large, polar
Pathway of G protein-linked receptor
Signal molecule binds to G protein - linked receptor →non active G protein looses GDP and gains GTP → G protein is now active → active G protein activates enzyme → cellular response /
Pathway of ligand gated ion channel
Ligand binds to closed gate → gate opens and ions pass through → cellular response → ligand leaves → gate closes
Transduction
Converting signal into cellular response
Transduction usually involves multiple…
relay molecules
Relay molecules, second messengers, and phosphorylation cascades are involved in…
Transduction
Second messengers are
Small, non protein, water soluble molecules
Phosphorylation cascade
Relay of message or series of phosphorylations
Protein kinase
Enzyme that phosphorylates protein substrates
Protein prosphatases
Enzyme that removes a phosphate group (often used to turn off a pathway)
Apoptosis
Programmed cell death
What does epinephrine do?
Signals liver cells to breakdown glycogen to increase blood glucose levels
Amplification
Of products at each step of pathway are greater than the step before (few molecules lead to a large response)
Specificity of response,
One signaling molecule can cause different cells to have different responses
Benefits of multistep pathway
Specificity of response and amplification
Cells within a population communicate via…
Signal factors/molecules
