Biological Membranes Flashcards
Functions of plasma membrane
Cell signalling, cell adhesion, control of cytoskeleton
Phosphatidylcholine
Most common phospholipid - choline attached to ionic head making it hydrophilic
Plasma membrane structure
Composed of two layers - hydrocarbon tails face away from the hydrophilic extracellular/intracellular environments while polar heads face outside of membrane
Cholesterol
Fatty acid - Found in gaps between phospholipids, stiffens cell membrane and reduces permeability, affecting regulation of cell membrane pathways
Transmembrane proteins
Span the whole width of the plasma membrane
Proteins embedded in the plasma membrane
Are important in facilitating the transport of molecules across the membrane
Active transport
Requires energy from ATP to move molecules against the concentration gradient
Passive transport
Does not require energy - moves molecules down their concentration gradient
Positive ions
Will diffuse easily from outside to inside the cell
Na+/K+ pump
Uses energy of ATP hydrolysis to pump sodium out of the cell and potassium into the cell - against the concentration gradient
Uniport transporters
Transport one molecule by one transporter
Symport’s
Transport two molecules in the same direction
Antiport’s
Transport one molecule in one direction and one molecule in the other direction
Glucose symport
Uses the electrochemical Na+ gradient to drive the import of glucose into the cell
ATP binding cassette (ABC) class pumps
Use active transport to expel ions, drugs and xenobiotics from the cells
ABCB1
Implicated in multi drug resistance - expelling therapeutic drugs designed to kill/inhibit them - especially chemotherapeutic agents
