Membrane structure and function - August 24 Flashcards
describe the basic phospholipid structure with a glycerol backbone
it has a glycerol backbone linked to 2 nonpolar fatty acid chains and a polar phosphate group
describe the basic phospholipid structure with a sphingosine backbone
usually has an O-linked to a charged group and amide linked to an acyl group such as a fatty aicd
how do saturated vs unsaturated fatty acids affect fluidity
unsaturated fatty acids increase fluidity and permability
what can diffuse across the phospholipid bilayer and what cannot
can: O2, N2, H2O, CO2, and hydrophobic compounds
cannot: charged molecules, glycine and AA’s
what are liposomes and what are they used for
artificially prepared vesicle composed of a lipid bilayer used to administer and transport nutrients and drugs in the body
what are the functions of membrane proteins
cell to cell contract (cell adhesion)
- receptor signaling systems
- pores and channels (transport)
-enzymes
what do flippases do
use ATP to move a molecule from out to in
what do floppases do
use ATP to move molecules and cholesterol from in to out
what do scarmblases do
move a molecule from outer to inner membrane while moving cholesterol from inner to outer membrane and does not require ATP
what does lipid orientation look like in the ER membrane
it is a symmetrical bilayer where concentration of lipids on the inner membrane = concentration of the lipids on the outer membrane
what does the lipid orientation look like in the plasma membrane
it is asymmetrical
what catalyzes flipping of phospholipid molecules in ER membrane
scramblases
what catalyzes flipping of phospholipids in plasma membrane
flippase
what are lipid rafts
specialized domains in plasma membranes of cells which organize membrane proteins and glycolipids into groupings involved in receptor trafficking, neurotransmission, and membrane fluidity
what are lipid rafts enriched with
cholesterol and sphingolipids
what are lipid rafts resistant to
detergents
what are caveolae
invaginations of the plasma membrane caused by lipid rafts
what signaling events do lipid rafts play a role in
B-cell antigen receptor, T-cell antigen receptor, and IgE receptor
describe what membrane fusion is
virus attaches to cell membrane of recipient cell via receptors followed by fusion where cell releases into contents into other cell
where are ACE2 receptors found
respiratory epithelial cells, this is why COVID is respiratory symptoms
what is the chemical structure of a triglyceride
glycerol bound to three fatty acid molecules
what is the chemical structure of a fatty acid
a straight chain of an even number of carbon atoms with a carboxyl group at one end and a hydrogen atom at the other
what does arachidonic acid do and what is it released by
released from phospholipids by phospholipase and it it used to produce prostaglandins
what are prostaglandin molecules and what do they do
short-acting signaling molecules that function through only paracrine or autocrine signals
