Lec 2- Cell Membrane and Transport Flashcards
Fluid mosaic model
View of the membrane to show its contents as “icebergs”.
Amphipathic
Containing both hydrophobic and hydrophilic parts.
Makes up the phopholipid bilayer.
Diffusion
Simple: uniform spreading out of molecules due to their random intermingling.
Dynamic equilibrium
Movement of molecules is equally matched on both sides.
Channels
Proteins found across the membrane that are water filled.
Carriers/Transporters
Other proteins that span the membrane; they transfer across membrane specific substances that are unable to cross on their own.
Active transporters/pumps
Requires energy to move a substance across the membrane.
Cations
Positively charged ions.
Anions
Negatively charged ions.
Permeability
A substance is able to cross the membrane on its own.
Ligand or Voltage-Gated
These channels open or close in response to changes in membrane potential.
Uniporter
An integral membrane protein that transports a single type of substrate species (charged or uncharged) across a cell membrane.
Antiporter
An antiporter (also called exchanger or counter-transporter) is a cotransporter and integral membrane protein involved in secondary active transport of two or more different molecules or ions across a phospholipid membrane such as the plasma membrane in opposite directions.
Tm - Transport maximum
The amount of a substance carriers can transport across the membrane in a given time is limited.
Na+/K+ ATPase (pump)
Transports Na+ out of the cell and picks up K+ for the cell.
