Cell Membranes
Topic 2 – Cell membranes
Reading
Chapter 5
Objectives
Functions of cell membranes
The fluid mosaic model
The lipid bilayer – phospholipids, glycolipids and sterols
Properties of the lipid bilayer
Membrane proteins – the ‘mosaic’ in the model
Solute movements across membranes
BIO 1140 – SLIDE 1
http://www.nikonsmallworld.com/gallery/year/2006/id/751
Functions of cell membranes – an overview
Fluid mosaic model
Singer & Nicolson 1972
Fluid lipid molecules in which proteins are embedded and freely floating. floating Functions
Define boundaries; selectively permeable barrier
2. Localisation and organisation
1.
Scaffold for biochemical activities (enzymes)
e.g. mitochondria
Fig. 7-2, Becker et al. 2009
BIO 1140 – SLIDE 2
3.
Regulation of solute transport
4.
Responses to external signals
5.
In and out of cell and/or organelles
Uphill or downhill
e.g. Na+,K+-ATPase
Receptors and signal transduction
e.g. ß-adrenoreceptor
Cell-to-cell communication
Recognition, adhesion, exchange of materials Gap junctions, plasmodesmata
Fig. 7-2, Becker et al. 2009
BIO 1140 – SLIDE 3
Plasma membrane of Schwann cell (myelin sheath)
18% protein
82% lipid
Inner mitochondrial membrane
76% protein
24% lipid
BIO 1140 – SLIDE 4
Figs. 6.8, 33.5
Membrane structure
Fluid mosaic model
Lipid-protein assembly in which components are held together in a thin sheet by non-covalent bonds
Two fluid lipid layers – structural backbone, permeability barrier
Mosaic of proteins – unique complement responsible for specific functions
~10 nm thick BIO 1140 – SLIDE 5
Fig. 5.1
Membrane structure
Fluid mosaic model
Lipid-protein assembly in which components are held together in a thin sheet by non-covalent bonds
Two fluid lipid layers – structural backbone, permeability barrier
Mosaic of proteins – unique complement responsible for specific functions
~10 nm thick BIO 1140 – SLIDE 6
Fig. 5.2
Reading
Chapter 5
Objectives
Functions of cell membranes
The fluid mosaic model
The lipid bilayer – phospholipids, glycolipids and sterols
Properties of the lipid bilayer
Membrane proteins – the ‘mosaic’ in the model
Solute movements across membranes
BIO 1140 – SLIDE 1
http://www.nikonsmallworld.com/gallery/year/2006/id/751
Functions of cell membranes – an overview
Fluid mosaic model
Singer & Nicolson 1972
Fluid lipid molecules in which proteins are embedded and freely floating. floating Functions
Define boundaries; selectively permeable barrier
2. Localisation and organisation
1.
Scaffold for biochemical activities (enzymes)
e.g. mitochondria
Fig. 7-2, Becker et al. 2009
BIO 1140 – SLIDE 2
3.
Regulation of solute transport
4.
Responses to external signals
5.
In and out of cell and/or organelles
Uphill or downhill
e.g. Na+,K+-ATPase
Receptors and signal transduction
e.g. ß-adrenoreceptor
Cell-to-cell communication
Recognition, adhesion, exchange of materials Gap junctions, plasmodesmata
Fig. 7-2, Becker et al. 2009
BIO 1140 – SLIDE 3
Plasma membrane of Schwann cell (myelin sheath)
18% protein
82% lipid
Inner mitochondrial membrane
76% protein
24% lipid
BIO 1140 – SLIDE 4
Figs. 6.8, 33.5
Membrane structure
Fluid mosaic model
Lipid-protein assembly in which components are held together in a thin sheet by non-covalent bonds
Two fluid lipid layers – structural backbone, permeability barrier
Mosaic of proteins – unique complement responsible for specific functions
~10 nm thick BIO 1140 – SLIDE 5
Fig. 5.1
Membrane structure
Fluid mosaic model
Lipid-protein assembly in which components are held together in a thin sheet by non-covalent bonds
Two fluid lipid layers – structural backbone, permeability barrier
Mosaic of proteins – unique complement responsible for specific functions
~10 nm thick BIO 1140 – SLIDE 6
Fig. 5.2