lecture 2 Flashcards
what is 2 phase system?
Monomers of lipids are in solution together with their micells
Gibbs free energy of micelle formation
Difference in standard chemical potentials of lipid monomers in the micelle and monomers in solution
what is CMC
the maximum concentration of lipid monomers coexisting with their micelle form
How can CMC be determined
tracking surface tension, osmotic pressure, conductivity and other colligative properties
packing paremeter bigger than 1?
Inverted cone
Packing parameter less than one
cone pointing downwards
What does the main phase transition temperature of membrane phospholipids depend on?
The nature of the polar head groups + the length of the hydrophobic chain. the degree of unsaturation of lipid tails.
sometimes,
it is affected by the pH and the presence of ions
……Rotation……packing
…….packing……rotation
more, less
less, more
Cholesterol can induce the coexistance of ….
Liquid ordered and liquid disordered states
what happens if the solubility of cholesterol in membranes is exceeded
Cholesterol forms crystals
What is GPI-anchor
Is glycosylphosphatidylinositol used to anchor certain peripheral proteins
How is GPI-anchored released?
Released by the use of phospholipase C
certain ways to remove integral proteins from the membrane
Detergents
Proteins with intrinsic curvature can help with what?
examples?
helping bending membranes for endocytosis and exocytosis. BAR proteins at the membrane surface
How are integral proteins held in membranes
Through hydrophobic interactions with the surrounding lipids
…% to ….% of all proteins are integral membrane proteins
10 -20
The length of the unbroken sequence of integral membrane proteins
20
Hydrophobicity? negative and positivty?
hydrophillic, hydrophobic
Indole ring is found in which amino acid?
tryptophan
Which residues in membrane proteins cluster at the water lipid interface ?
tryptophan + tyrosin
which secondary structures are present in membrane pores?
alpha-helices
which are larger alpha-helical pores or B-barrels
B-barrels
Pressures arising from lateral diffusion
Positive (repulsions between head groups)
positive (repulsion between the hydrophobic side chains)
negative (interface between water and the hydrophobic part of the lipid. (interfacial tension).
