membrane structure and function Flashcards
plasma membrane
phospholipid bilayer
contains proteins and sugars attached to lipids and proteins
membrane lipid
phosphatidylcholine
phosphatidylethanolamine
phosphatidyl serine
spingolipids (no glycerol)
function of phosphatidylcholine
naturally forms bilyae
contains choline
kinked tails for fluidity of membrane
phosphatidylethanolamine
inner leaflet
stabilises membrane structure
amine group creates charge and bondnig
cholererol
increases fluidity
lipid soluble
lipid rafts
formed due to cholesterol moving in membrane
can bring proteins together associated with rafts
regulated function of membrane protiens
GPI protiens
joined to membrane by sugar
associated by rafts and brought together
influence signalling and function of proteins in membrane
disruption of lipid rafts
alters protein fucntion
alcohol or high cholesterol
membrane protiens
transporters
anchors
receptors
enzymes
mechanisms of transport
diffusion
facilitated diffusion
gated channels
active transport
facilitated diffusion
solute binds to proteins
protein changes conformation
down conc gradient
gated channels
proteins form a pore for molecules that cannot diffuse normally
open and close due to signal/stimulus
active transport
primary
movement of one moecule up a concentration gradient using ATP
secondary
false electrochemical gradient created by pumping a molecule out
allows molecule to diffuse back in with another molecule (co transport)
types of transporters
symport - 2 molecules the same way
uniport - one moecule
antiport - 2 molecules oppositie ways
ionophore mediated tranpsort
lipids that are able to pass through membrane encase another molecule
anchors
anchor the cell to ECM
integrins common anchors
binds cytoskeleton and ECM
receptors
autocrine - same cell
juxta crine - adjacent cell
paracrine - close cells
endocrine - through blood stream, long distance
types of membrane bound receptors
ion channel
heptahelical
kinase associated receptors
ion channel receptors
associated with protein channel
when ligand binds, receptor changed shape and nudges protein which alters conformation for ions to flow through
heptahelial receptors
7 alpha helices through the membrane
binding causes intracellular changes
involves second messenger
kinase associated receptor
binding of signal causes phosphorylation intracellularly
2 receptors in membrane, tyrosine inside cell
signal binds, receptors move together
tyrosine becomes phosphorylated
causes further phosphorylation in the cell of protiens
signal reaches nucleus
membrane bound enyzymes
can act as receptors
can cleave other proteins
catalyse reactions
angiotensin system
ACE in membrane
ANG I in blood stream
enzyme catalyses ANGI to ANGII
can then bind to receptor
what is cancer due to
over effect of kinase receptor
Her2 protein receptor can be overproduced, cell divides rapidly
