Forces Acting Across Membranes 2 Flashcards
What are forces moving water and other molecules driven by?
Concentration gradients.
Is there a large flux of ions when the channels open?
No, but it is enough to change the electrical status of the cell.
What does the net effect of 2 electrical charges create?
Electrochemical gradient.
What are endocytosis and exocytosis?
Mechanisms for moving macromolecules without disrupting the membrane.
What is the endocytosis mechanism?
Invagination of membrane to form a vesicle which separates on the cytoplasmic surface and migrates within the cell to its destination. Example - WBC
What is the exocytosis mechanism?
Materials are exported out of the cell via secretory vesicles. Example - Neurotransmitters
Define diffusion.
Process of a gas or substance expanding to fill all the available volume. The substance will spread until the concentration is uniform throughout the whole cell.
What is the equation for the magnitude of net flux?
F=kpA (c1-c2)
What can diffuse through the lipid bilayer?
Small, lipophilic, uncharged molecules.
Define channels.
Act as aqueous rate for diffusion of ions, only allow small mineral ions like sodium to pass.
What is the electrochemical gradient?
The combination of chemical and electrical gradient
Defined facilitated diffusion.
Movement of molecules through transport proteins down their electrochemical gradient.
