lecture 2 Flashcards
permeability of lipid bilayer
artifical bilayer is impermeable to most soluble water molecules
cell membrane uses transport proteins to transport speficic molecules (facilitated transport)
permeable
simple diffusion, going from high concentration to low concentration, faster diffusion of hydrophobic/non polar molecules, faster when small
impermeable
require membrane proteins for them to go across the membrane
transmembrane transport proteins
create a path across the membrane, transport polar and charged molecules, they are selective, two main classes
channel
no conformational changes, selective of size and electric charge, transient interactions as solute passes through
transporters
selective of what fits in binding site, like lock and key, speficic binding of solute, goes through conformational changes
simple diffusion
molecules just go through the membrane, needs no help
passive
channel, transport mediated when with concentration gradient, no energy needed
active transport
energy needed, when going against the gradient
electrochemical gradient
concentration gradient+ membrane potential= elevtrochemical gradient
electrochemical gradient
when there is a membrane potental
concentration gradient
there is no membrane potential
channel proteins
hydrophilic pore across the membrane, they are selective of ion size and charge, they are passive transport, they are faster than transporters
ion channels
they are found in animals, plants, and microorganisms, gated and non gated
non-gated ion channels
they are always open, major role in generating resting membrane potential in plasma membrane of animal cells
K+ leak channels
gated ion channels
signal is requited for the channel to open
signal could be, mechanical stress, ligand (whether extra or intra cellular), or a change in voltage across the membrane
transporter proteins
they bind to a specific solute, they go through cinformational changes
uniport, symport, antiport, p-type pump, v-type pump, ABC transporter
uniport
only one solute, passive transport down the electrochemical gradient, the direction of transport is reversible
gradient driven pump
1st solute goes down its gradient and created energy which allows the second solute to go against its gradient
symport and antiport
ATP-driven pump
ATP hydrolysis of energy, tje solute moves against its gradient and ATP is turned to ADP
light driven pump
light energy, solute moves against its gradient
symport
two solutes, they move in the same direction
Na+ down its electrochemical gradient provides energy for glucose to move against its gradient, they go the same way
antiport
two solutes, move in oposite direction
Na+ goes down its electrochemical gradient and provides energy for H+ to move against its electrochemical gradient in the opposite direction
Na+ electrochemical gradient maintness
both symports and antiports, the continued action of the gradient driven pumps keeps an equilibrium in the Na+ gradient
p-type pump
ATP driven, phosphorylated, ion transport that builds up/maintains electrochemical gradients
Na+-K+ pump
both move against their gradient
3Na out 2 K in
keeps inbalance
the Na gradient is used tp transport nutrients such as glucose into the cell and maontain pH
ABC transporter
uses 2 atp to pump small molecules across cell membrane
v-type proton pump
uses ATP to pump H+ into organelles to acidify the luman
uses atp rto pump H+ against electrochemical gradient
f-type ATP synthase
structurally related to V-type proton pump but its the opposite, uses h+ gradients to drive the synthesis of ATP, uses electrochemical gradient to produce atp, reversibe
transport protein processes used to regulate critical cellular processes
transcellular transport of glucose by transporters, work together to transfer glucose from intenstine to blood stream
membrane potential
difference in electrical charge on two sides of the membrane
generation of membrane potential animals
K+ leak channel, outward flow of K+
Na-K pumps, maintaines gradient of Na with low cytosolic and high cytosoluc K
cell generally balance electrical charged inside and out of the cell
generation of membrane potential plants
Plasma membrane p-type pump
generates H+ electrochemical gradient`
