summary Notes

Cell signalling

Principles of the cell signalling
 Sense the environment

 To function in the appropriate manner with neighbouring and distant cells within the
organism.

 Cells are made to respond to signals in particular ways.

 Likely for different cells to respond to the same signal but in different ways.




Types of cell communication

1. Paracrine: changes in neighbouring cells

2. Autocrine: regulate self or group of similar cells, growth signalling

3. Gap junctions: direct contact with adjacent cell cytoplasm and transport ions and
molecules between the cells.

4. Endocrine: transmits signals over long distant, hormones

, Cell signalling steps



Reception: a cell detects a
signalling molecule outside the cell
and the signal is detected. When
the chemical signal (ligand) binds to
the receptor protein on the surface
of the cell or inside the cell.


Transduction: when the
signalling molecule binds to
the receptor it changes the
receptor protein and this
change initiates the
transduction process.

Response: The signal triggers
a specific cellular response.



 Ligand is an agent that produces a signal either physical or chemical.


Receptor

 Binds to the signal molecule

 Cell surface receptors:
Binds to hydrophilic ligands and it is embedded in the plasma membrane

 Intracellular receptors:
Present in the cytoplasm or nucleus and binds to small and hydrophobic ligands.
 Activation of receptors:
Mediate signalling by recruiting G proteins and causes change in gene expression