week 2 Flashcards
three classes of membrane prot
integral
peripheral
lipid anchored
how are proteins distributed across a mem
assymetrically
how are peripheral mem prot interact with the mem
via weak non covalent bonds
they are polar
are peripheral mem prot dynmaic>
yes. the often are associated with movement either to or from the mem
roles of peripheral prot
-signal transduction
-mechanical suport (shape mem)
-anchor for integral mem prot
-act as enzymes
which proteins are responsible for RBC shape. where are they found
spectrin
found on the integral (inside) to give concave shape
lipid anchored prot location
-on the extracelluar or cytoplasmic side
lipid anchored prot mem attachment
via covalent bonds to a lipid mole
2 types of lipid anchored prot
-GPI anchored prot
-Hydrocarbon chains embedded in the bilayer
GPI anchored prot
Glycosyl-Phosphatidyl Inositol linkage
-only ont he extra cell side
- role= cell adhesion and receptors
hydrocarbon chains embedded in the lipid bilayer
direct linkage
on the cyto and extra cell sides
signal transduction role
phospholipid dynamics
-easy and fast later movement
- restricted flip flop movement. this is because it is thermodynamically unfavourable due to the requirement of the polar head needing to pass through the non polar ‘tail region’
flippase
the enzyme responsible for establishing membrane asymmetry
which lipid type can flip flop the easiest
cholesterol. due to its small polar head and large non polar ring structure
membrane prot dynamics
movement of particles via
1) random diffusion
2) immobilized (no movement)
3) particular direction (motor prot)
4) restricition by other integral mem pot
5) restriction via mem skeleton
6) restrain via extracellular materials
selectively permeable
allow the passage of some substance but inhibit the passage of others
active vs passive transport
active= energy and against conc grad
passive= diffusion and no energy
types of diffusion
-via mem
-via channel
- via facilitative transporter
what does active transport use
pumps
diffusion
the spont process that a substance moves from high conc to low conc, until equib is achieved
conc gradient
the diff in conc of a sub between two areas
simple diffusion
the penetration of the membrane by small, uncharged, non polar (typically) particles. these are inorganic or have high lipid solubility
thougb water is an exception as it moves via osmosis
osmosis
movement of water from a low conc of solution to high conc of solute
hypertonic solution
when the surrounding solution is more concentrated than the cell. water will move out and cell shrinks
hypotonic solution
the surrounding solution is more diulte the n cells interior and water will move into the cell and swell
diffusion through a channel
aquaporin- transport water
ion chanel- permeable to specific ions and are highly selective and operate through a gated system
gated channel system
a specilaized requirement to be met to change its conformation, either opening or closing the channel
types of gated channels
voltage
ligand
mechano gated
voltage gated
open/ close based on ionic charge on either side of a mem
eg. nerve impulse
ligand gated
the bidning of a specific mole
eg neuro transmitter
ligands are moles that is not the solute being transported
mechanogated
open/ close based on the mechanical forces
eg moving a body part
what do K+ ion channels responsible for
voltage gated
transmit electrical impulses along axonx
channels are regualed via differneces in membrane voltage (diff across a mem)
