Endomembrane system 11/11/19
Cell = unified system – communication – determines how cell works
- Endomembrane system = inside membrane
- Located in cytoplasm – tethered in place
- Structural divide – cells = different compartments
- Functional diversity – different [organelles] in different cells – based on function
Inside of cell and outside have structural links – communication
Plasma membrane:
- Compartmentalisation – cell = separated from outside env.
- Transport – macromolecules in/out – selective permeability
- Signal transduction – receptors – causes events in cell – evokes biological response
- Intracellular junctions – tightly packed cells – form tissues – cells communicate with each
other – e.g. – cardiac tissue – allows cardiac muscle contraction
Phospholipid bilayer – hydrophobic head, philic tail
- Stable bilayer structure – between 2 aq. env
‘Fluid mosaic model’ – various specific proteins across full length of membrane, on outer surface or
inside cells
- Expression of receptors can identify cell types – unique to cells
- Important for immune response and homeostasis
Different processes of cellular mediation:
- Transport – movement of ions/macromolecules – v. important for membrane potential
- Enzyme activity
- Signal transduction
- Cell-cell recognition – cell presents receptor – may bind to T cell in immune response
- Intercellular joining
- Attachment of cytoskeleton and ECM (matrix) – ECM senses changes in external env – evokes
changes in cell
Membrane = fluid – phospholipids move across membrane – maintains integrity and function of cell
- Often move laterally – rapid process
Several factors affect lipid structure
- Fluidity = affected by temp
- Steroids
- May change function/integrity of cell
Organelles = compartmentalised to allow division of labour
- More efficient
- More activity in animal cells
- Membranes increase surface area for reactions
- Allows cells to vary within tissues based on function
Cell = unified system – communication – determines how cell works
- Endomembrane system = inside membrane
- Located in cytoplasm – tethered in place
- Structural divide – cells = different compartments
- Functional diversity – different [organelles] in different cells – based on function
Inside of cell and outside have structural links – communication
Plasma membrane:
- Compartmentalisation – cell = separated from outside env.
- Transport – macromolecules in/out – selective permeability
- Signal transduction – receptors – causes events in cell – evokes biological response
- Intracellular junctions – tightly packed cells – form tissues – cells communicate with each
other – e.g. – cardiac tissue – allows cardiac muscle contraction
Phospholipid bilayer – hydrophobic head, philic tail
- Stable bilayer structure – between 2 aq. env
‘Fluid mosaic model’ – various specific proteins across full length of membrane, on outer surface or
inside cells
- Expression of receptors can identify cell types – unique to cells
- Important for immune response and homeostasis
Different processes of cellular mediation:
- Transport – movement of ions/macromolecules – v. important for membrane potential
- Enzyme activity
- Signal transduction
- Cell-cell recognition – cell presents receptor – may bind to T cell in immune response
- Intercellular joining
- Attachment of cytoskeleton and ECM (matrix) – ECM senses changes in external env – evokes
changes in cell
Membrane = fluid – phospholipids move across membrane – maintains integrity and function of cell
- Often move laterally – rapid process
Several factors affect lipid structure
- Fluidity = affected by temp
- Steroids
- May change function/integrity of cell
Organelles = compartmentalised to allow division of labour
- More efficient
- More activity in animal cells
- Membranes increase surface area for reactions
- Allows cells to vary within tissues based on function
