Movement Of Molecules Across The Membrane Flashcards
What’s a fluid mosaic model
A model that describes the structure of the cell membrane
LEARN HOW TO LABEL THE PHOSPHOLOID BIYLAER
What do regions of hydrophobic R groups allow
String hydrophobic interactions that hold integral membrane proteins within the phospholipid bilayer
What do integral membrane proteins do
-Interact extensively with the hydrophobic region of membrane phospholipids
-some are transmembrane proteins so they spam the entirety of the cell membrane
What are peripheral membrane proteins
Have Hydrophilic R groups on their surface and are bound to the surface of membrane mainly by ionic and hydrogen bond interactions
What do many peripheral membrane proteins do
Interact with the surfaces of integral membrane proteins
What is the phospholipid bilayer
Is a barrier to ions and most uncharged polar molecules
How to small molecules pass through the bilayer
Oxygen and c02 pass through by simple diffusion
What is facilitated diffusion
The passive transport of substances across the membrane through specific transmembrane proteins
Why do different cell types have different channels and transporter proteins
To perform specialised functions
What are channels
Multi subunit proteins with the subunits arranged to form water filled pores that extend across the membrane
What are most channel proteins
Highly selective meaning they let very few types of molecules pass through
What do some channel proteins do
They are gated and change conformation to allow or prevent diffusion
What are ligand gated proteins controlled by
The binding of signal molecules
What are voltage gated channels controlled by
Changes in ion concentration
What do transporter proteins bind to and undergo
They bind to specific substance to be transported an undergo a conformational change to transfer the solute across the membrane
Why do transporters alternate between two conformations
So that the binding site for a solute is sequentially exposed on one side of the bilayer then the other
What does active transport use
Pump proteins that transfer substances across the membrane against their concentration gradient
What are pumps that mediate active transport
Transporter proteins coupled to an energy source
What is required for active transport
A source of metabolic energy
What do some active transport proteins do
Hydrolyse ATP directly to provide the energy for the conformational change required to move substances across the membrane
What is ATP hydrolysed by in active transport
ATPases
