Molecules and Cells Flashcards
How can cells communicate with one another?
Between cells - electrically or chemically
Within cells
How do gap junctions work?
They allow flow of current from cell-to-cell
Rapid transmission in both direction
Linked cells act as one unit
What are the types of chemical transmission between cells?
Synapse (cell-cell)
Paracrine (cell-several cells)
Endocrine (many cells-many cells)
Describe synaptic sequence of events.
- Impulse arrives at terminal of presynaptic cell
- Transmitter released from storage vesicles
- Transmitter diffuses in synaptic cleft
- Transmitter binds to receptor on postsynaptic cell
- Alters postsynaptic cell - excitatory or inhibitory
What is ‘paracrine communication’?
One cell communicates with several cells locally
What is ‘autocrine communication’?
Chemical acts on cell releasing it (feecback)
What is endocrine communication?
Chemicals sent to all parts of body via blood
Hormone acts only on cells with correct membrane receptor
What are the properties of neural cell communication?
Actions often very specific or localised
Quick impulse transmission
Suitable for rapid responses
What are the properties of hormonal cell communication?
Can affect many cells in different parts of body
Co-ordinated, body-wide actions
Slow to act, but effect persists
What are first and second messengers?
They are intercellular signalling molecules
First - chemical transmitter which acts on receptor protein
Second - relay signals received at receptors on the cell surface
What is the action of steroid transmitters in relation to cell signalling?
Steroid are lipids that can pass through cell membrane
Bind to corresponding intracellular receptor
Complex acts on DNA to initiate protein synthesis
Protein alters cell function
What are Peptide transmitters?
Peptide transmitters cannot pass through cell membrane
Bind to plasma membrane receptors and set up a series of reactions controlled by ‘G-proteins’
In turn activate cyclic-AMP and calcium ion 2nd messenger systems
What enzyme converts ATP to AMP?
Adenyl cyclase
What activates G-protein?
GTP
What enzyme does cAMP activate?
Protein Kinase
