What is a Membrane? Flashcards
Phospholipids
main component of cell membrane
head of phospholipid
negatively charged, hydrophilic
tail of phospholipid
uncharged, hydrophobic
What do phospholipids do in aqueous solution
forms bilayer
head goes towards the water
tails go away from the water
Two characteristics of a membrane
fluid and impermeable to changed molecules
Fluid characteristic
phospholipid constantly moving (temperature dependant), cholesterol will provide some stability
Impermeable to changed molecules characteristic
water soluble substances (ions, proteins)
small uncharged molecules (oxygen, CO2) can move freely
hydrophobic interior
acts as barrier
Membrane proteins
peripherally associated protiens
integral protiens (incl. transmembrane)
Peripherally associated protiens
adhere to the cytoplasmic or extracellular surfaces of plasma membrane (not embedded)
Integral membranes
some are embedded but dont cross the lipid bilayer
some are linked to a lipid component that intercalates the membrane
some span the lipid bilayer
Six functions of membrane protiens
Ligand binding receptors (hormone receptors)
Adhesion Molecules, form physical contacts with the extracellular matrix or woth cellular neighbours (integrins, CAMs)
Transmembrane movement (three types)
Can be enzymes
intracellular signalling (associated with cytoplasmic surface)
Docking marker acceptors(exocytosis)
Three types of transmembrane movement
pores and channels for water pr specific ions
carriers - facilitated transport, or couple transport molecules to the other side
pumps x use ATP to drive transport
Membrane carbohydrates
Glycolax
Glycolax
glycoproteins and glycolipids located on outer surface of cells
