C2.1 Chemical Signaling Flashcards
Amine hormones
- Derived from amino acids (tyrosine & tryptophan)
- bind extracellularly
- EXAMPLE: Adrenaline
Peptide hormones
- Derived from proteins (peptide chains)
- bind extracellularly
- activate secondary messenger
- EXAMPLE: Insulin
Lipid hormones
- Derived from fats & lipids (cholesterol)
- bind intracellularly
- EXAMPLE: testosterone
Non-steroid hormones
- derived from amino acids & proteins
- bind extracellularly
- use secondary messenger
- effects are fast
Steroid hormones
- derived from lipids (cholesterol)
- bind to intracellular receptors
Cytokines
- small proteins involved in immune response
- secrete by white blood cells
- bind extracellularly
Calcium ions (Ca2+)
- released in response to external signals
- function intracellularly
- trigger cellular responses: muscle contraction, exocytosis
Autocrine signaling
Cell secreting the signal molecule uses it for itself
Paracrine signaling
Signal molecules are released to affect nearby cells
Endocrine signalling
Long-distance signaling using the bloodstream
Juxtracrine signalling
Signal is not released - direct cell-to-cell contact allows for contact between the ligand and receptor
Signal transduction pathways
Initial signal at the cell surface is converted into a specific cellular response
- Reception
- Ligand binds to receptor protein on cell membrane (or in cell)
- Receptor undergoes conformational change
- Example: G-protein coupled receptors
- Transduction
- Signal is relayed & amplified inside the cell
- activates a secondary messenger
- involves protein cascade
cAMP transduction pathway
- Adrenaline binds to a receptor
- Signal is relayed via cAMP
- Response: glycogen breakdown
- Cellular response
- final action taken by cell, triggered by pathway
- i.e activation of enzyme
- signal is terminated
Secondary messengers
Small molecules produced intercellularly in response to ligand binding to receptor
Quorum sensing
Production of auto-inducers which move across cells and diffuse into them
Quarum
Minimum amount of things needed to start a process
