Lecture 4: Transporters, Ion Channels And Pores Part 1 Flashcards
What is a semi-permeable membrane?
A layer through which only allowed substances can pass
What types of molecules can permeate a lipid bilayer?
Hydrophobic molecules and small uncharged polar molecules
How do proteins contribute to membrane permeability?
By forming membrane transport proteins (ping-pong transport)
By forming ion channels (ligand-gated and voltage-gated)
Where does the energy come from for membrane transport?
Directly or indirectly from ATP hydrolysis
How does water permeate a lipid bilayer?
- Water molecules are small and uncharged
- Moves by diffusion through the bilayer
- Driven by osmotic gradient of solutes
- Most move through aquaporin channels (hydrophilic pore made from proteins)
What is the definition of an electrochemical gradient?
Electrical and concentration gradient
What is passive transport?
Permeable molecules move from higher concentration to lower concentration
What is active transport?
Needs energy directly or indirectly from hydrolysis of ATP to overcome unfavorable chemical or electrical gradient
What is facilitated transport?
- Using channels (ligand-gated and voltage-gated), gap junctions and carriers to transport molecules
- Passive
What are uniports?
Transporter that transports one solute molecule alone from one side of the membrane to another
What are co-transporters?
When transfer of one solute molecule depends on the simultaneous or sequential transfer of another solute
What are symports?
When 2 solutes are transported in same direction
What are anti ports?
When 2 solutes are transported in opposite directions
