116A WEEK 9 – Cell Signalling
Learning outcomes:
1. Describe different forms of cell communication
2. Explain the mechanisms by which signals can activate cellular
processes
3. Explain the mechanisms by which signalling pathways can be
switched off
4. Describe some mechanisms that can lead to alteration of signalling
pathways and cellular functions
- Cellular processes are coordinated and regulated
How does a cell know what to do?
- Signals are released – highly specific – single instruction to a single
destination
- Signal is received
- Signal is converted into a biochemical reaction
- Cell carries out the instruction
- The direction of the message is important
, Timing and location
- Spatial recognition
o Specific processes occur in the specific compartments within
the cells where they are supposed to occur
o Only the cells that are supposed to respond do so
- Temporal regulation
o When it is required
o For as long as it is required
The following are examples of the two types of regulation:
- Temporal
o When should I divide?
o How long should I produce this protein?
o Should I stop dividing?
o When do I make this protein?
- Spatial
o Which tissues do I produce this protein in?
o Where should I produce this protein?
o Which cells should divide?
o Which cells need to respond?
Signal types
- Autocrine
o Producer and target = same cell
o Signal acts on itself
o Signal act on identical group of
cells
- Juxtacrine
o Ligand/signal = protein, lipid or
polysaccharide embedded in
membrane
o Receptor on plasma membrane of
target cell
o Contact dependent signalling
- Paracrine
o Target is a neighbouring, different
cell
o Ligand/signal often has a short life
o Received quickly and degraded quickly
o This prevents unwanted action further afield
- Endocrine
o Target is distant
o Ligand/signal travels through blood stream
o Very stable
o E.g. hormones and steroids
o Prevents wanted action further afield
o Endocrine system = glands that secrete products into the
blood
Learning outcomes:
1. Describe different forms of cell communication
2. Explain the mechanisms by which signals can activate cellular
processes
3. Explain the mechanisms by which signalling pathways can be
switched off
4. Describe some mechanisms that can lead to alteration of signalling
pathways and cellular functions
- Cellular processes are coordinated and regulated
How does a cell know what to do?
- Signals are released – highly specific – single instruction to a single
destination
- Signal is received
- Signal is converted into a biochemical reaction
- Cell carries out the instruction
- The direction of the message is important
, Timing and location
- Spatial recognition
o Specific processes occur in the specific compartments within
the cells where they are supposed to occur
o Only the cells that are supposed to respond do so
- Temporal regulation
o When it is required
o For as long as it is required
The following are examples of the two types of regulation:
- Temporal
o When should I divide?
o How long should I produce this protein?
o Should I stop dividing?
o When do I make this protein?
- Spatial
o Which tissues do I produce this protein in?
o Where should I produce this protein?
o Which cells should divide?
o Which cells need to respond?
Signal types
- Autocrine
o Producer and target = same cell
o Signal acts on itself
o Signal act on identical group of
cells
- Juxtacrine
o Ligand/signal = protein, lipid or
polysaccharide embedded in
membrane
o Receptor on plasma membrane of
target cell
o Contact dependent signalling
- Paracrine
o Target is a neighbouring, different
cell
o Ligand/signal often has a short life
o Received quickly and degraded quickly
o This prevents unwanted action further afield
- Endocrine
o Target is distant
o Ligand/signal travels through blood stream
o Very stable
o E.g. hormones and steroids
o Prevents wanted action further afield
o Endocrine system = glands that secrete products into the
blood
