Chapter 9 Flashcards
micelle
cone shaped, head greater than tail
bilayer
cylindrical, head equals tail
liposome
folded bilayer
cellular membranes consists of….
- lipids
- membrane proteins
Bimolecular reactions in membrane are more efficient than in….
solution
Probability of molecular collision in 2D plane is _______ than in 3D space.
higher
flippases
catalyze translocation of lipids from one side of bilayer to the other
uncatalyzed translocation of lipids from one side of bilayer to the other is….
slow af
below phase transition temperature, the membrane is…
in ordered paracrystalline state
at temperatures above phase transition, membrane is….
fluid
___________ is important for function
fluidity
______________ of the phospholipids is adjusted for proper membrane fluidity.
fatty acid composition
lipid raft
sphingolipids and cholesterol clustered together
lipid rafts are stabilized by…
interactions between the cholesterol ring and one saturated hydrocarbon tails of sphingolipids
lipids rafts function
attachment points for peripheral membrane proteins
how do lipid rafts and membrane proteins attach?
two covalently attached saturated acyl chains or glycosylated phosphoinositol derivatives (GPI)
intergral membrane proteins
usually span the bilayer with parts exposed on both sides; can be extracted with detergents
peripheral membrane proteins
most in cytosol or extracellular space, some attached to membrane (non-covalent interaction or lipid anchors)
proteins anchored to membrane by GPI are….
always outside the cell
proteins anchored by fatty acyl or prenyl chains are ….
always inside the cell
in intergral membrane proteins, charged residues are located mostly…
outside the membrane
residues with _____________ dominate the inside
apolar side chains
a-helical bundle
7 helices bonded together
B-barrel
22 strands closing on itself (1 H bond…?)
the __________ in the hydrophobic core of bilayer _______ regular secondary structures.
apolar environment, stabilizes
membrane fusion
membrane vesicles that exist in cells fusing with plasma membrane and themselves (exocytosis, endocytosis, fusion of sperm and egg, cell division)
How can a neutron cross the junction?
membrane vesicles full of Ace released to synaptic cleft, diffuse, interact with receptors, which serve as signal to open
free energy equation for diffusion with both concentration and electric component
deltaG=-mFdeltaΨ +2.3RTlog[Cin]/[Cout]
electric potential different favours movement of _ charge ions from _____ to _______
+, outside to inside
electric potential different favours movement of _ charge ions from _____ to _______
+, outside to inside
deltaG<0
favourable
deltaG>o
unfavourable
primary active transport
against electrochemical gradient
secondary active transport
against electrochemical gradient, driven by ion moving down its gradient
passive transport
transport down electrochemical gradient
channels
can only transport molecules and ions down the electro gradient
rate of transport though channel is ….
proportional to substrate concentration
carriers
can catalyze both active and passive transport
-generally lower rate of transport than channels due to rate limiting step
glucose transporter carrier equation
Vo=(Vmax[S]out)/(Kt+[S]out)
polar side chins form __________ with glucose in transporter interior
hydrogen bonds
uniport
passive carriers of one substrate
symport
2 substrates in same direction
antiport
2 substrate in opposite direction
electroneutral
no net charge flow
electrogenic
transports 1 charge across membrane
ATP hydrolysis is…
highly exergonic reaction
primary active transporters powered by ATP hydrolysis
Na+, K+, -ATPase
large scale domain movement are involved in ion transport by…
Ca+2-ATPase
which allow greater freedom of movement… a-helical or B-barrel?
a-helical
ATP synthase
convert energy of proton gradient to make ATP
-reversible
secondary active transporters operate by..
rocket switch mechanism
how does the rocket switch mechanism operate
exposing the binding site from cytoplasm (state I) to extracellular space (state II) is triggered by protonation and deprotonation of charged residues in the interior
transition between two states in rocket switch mechanism requires…
binding affinity of state I to be lower than state II
Na+K+ ATPase hydrolyzes ATP and that energy is …
used to pump sodium ions out of the cell and potassium ions in
3 important properties of protein ion channels
- high conduction rates
- selectivity
- gating
