MEMBRANE STRUCTURE
AND FUNCTIONS
MICRO LESSONRaquel Spencer
The Fluid Mosaic Model
This model proposes that membranes are not rigid, with molecules locked into place
Membranes consist of lipid molecules in which proteins are embedded and float freely.
The cell membrane is made of different parts working together, like a mosaic, made of many tiles of proteins
The lipid and protein molecules are generally free to move laterally within the two layers
Glycolipid
Carbohydrate group
Peripheral Protein
Phospolipid Bilayer
Transport Protein (integral)
Cholesterol
Integral Protein
The Role Phospholipids
THE HEADpolar = hydrophilic Interacts with water on the outside of the cell
Phosphate
Glycerol
THE TAILSnon-polar = hydrophobic Repelled by water, forced to face the interior of the cell
Saturated fatty acid
UNsaturated fatty acid
A bilayer forms spontaneously in an aqueous environment because of the tendency of the non-polar hydrophobic fatty acids to aggregate together while the polar heads associate with water.
Fluidity
Influenced by:
- Position of lipids molecules
- Temperature
Max. # Hydrogens = linear chains More rigid
Fewer HydrogensMore C=C
Hydrophilic end
Hydrophobic end
Hydrophobic Tail
The role of Membrane Proteins
Functional categories:
Transport
Enzymatic activity
Membranes are not designed for free diffusion of substances, but specific compounds can cross them through hydrophilic protein channels or shape shifting membrane proteins.
Some membrane proteins, such as those associated with respiration and photosynthesis, are enzymes.
Functional categories:
Attachment & Recognition
Triggering signals
Proteins exposed to membrane surfaces serve as attachment points for cytoskeleton elements, cell-cell recognition components, and bond to the extracellular matrix, enabling them to recognize disease-causing microbes and trigger an immune response.
Membrane proteins may bind to specific chemicals, such as hormones. Binding to these chemicals triggers changes on the inner surface of the membrane, starting a cascade of events within the cell.
MEMBRANE STRUCTURE
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Transcript
MEMBRANE STRUCTURE
AND FUNCTIONS
MICRO LESSONRaquel Spencer
The Fluid Mosaic Model
This model proposes that membranes are not rigid, with molecules locked into place
Membranes consist of lipid molecules in which proteins are embedded and float freely.
The cell membrane is made of different parts working together, like a mosaic, made of many tiles of proteins
The lipid and protein molecules are generally free to move laterally within the two layers
Glycolipid
Carbohydrate group
Peripheral Protein
Phospolipid Bilayer
Transport Protein (integral)
Cholesterol
Integral Protein
The Role Phospholipids
THE HEADpolar = hydrophilic Interacts with water on the outside of the cell
Phosphate
Glycerol
THE TAILSnon-polar = hydrophobic Repelled by water, forced to face the interior of the cell
Saturated fatty acid
UNsaturated fatty acid
A bilayer forms spontaneously in an aqueous environment because of the tendency of the non-polar hydrophobic fatty acids to aggregate together while the polar heads associate with water.
Fluidity
Influenced by:
Max. # Hydrogens = linear chains More rigid
Fewer HydrogensMore C=C
Hydrophilic end
Hydrophobic end
Hydrophobic Tail
The role of Membrane Proteins
Functional categories:
Transport
Enzymatic activity
Membranes are not designed for free diffusion of substances, but specific compounds can cross them through hydrophilic protein channels or shape shifting membrane proteins.
Some membrane proteins, such as those associated with respiration and photosynthesis, are enzymes.
Functional categories:
Attachment & Recognition
Triggering signals
Proteins exposed to membrane surfaces serve as attachment points for cytoskeleton elements, cell-cell recognition components, and bond to the extracellular matrix, enabling them to recognize disease-causing microbes and trigger an immune response.
Membrane proteins may bind to specific chemicals, such as hormones. Binding to these chemicals triggers changes on the inner surface of the membrane, starting a cascade of events within the cell.