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4.3 Roles of the molecules found in membranes - Coggle Diagram
4.3 Roles of the molecules found in membranes
Phospholipids
Forms bilayer, the basic structure of membrane
Fluidity affected by length of tail and unsaturatedness
Hydrophobic core of tails stops dissolved polar molecules/ions from passing through membrane
Sugars/amino acids cannot leak out of cell
Membrane acts as barrier
Cholesterol
Hydrophilic head and hydrophobic tail, like phospholipid
Animal cell surface membranes have lots of cholesterol
Plant cell surface membranes have not much cholesterol
Prokaryotes have no cholesterol
Reduces fluidity by getting in between phospholipids
Stops membranes from breaking (cell lysis)
Hydrophobic tails stop dissolved polar molecules/ions from passing through membrane
Used in myelin sheath with multiple layers of membrane - less ions leaking = stronger nerve impulse
Proteins
Transport proteins have hydrophilic passageways
Allows polar molecules/ions to pass through
Each transport protein is specific to a certain ion
Enzymes can be found in cell surface membrane
Cytoskeleton may be attached to proteins in cell surface membrane - supports cell shape
Glycoproteins and glycolipids
Receptor molecules bind with substances at cell surface
Antigens allow cells to recognise each other
Each type of cell has own type of antigen
Important for immune response