BIOB34H3 Lecture Notes - Lecture 8: Cotransporter, Paracellular Transport, Cytosol

• School: UTSC
• Department: Biological Sciences
• Course: BIOB34H3
• Professor: Blake Richards

Document Summary

In the absence of energy, molecules always go down their electrochemical gradient until equilibrium is reached (maximum entropy) When the membrane depolarizes: voltage close to 0, or polarizes in the positive direction the change in the free energy landscape of this protein now moves into a shape which it is open and permits molecules through: phosphorylation-gated. Channel: opened/closed by adding a covalent bond to a phosphate group via an enzyme that acts like a signal: stretch-gated (tension-gated) Channel: channels that are attached to the cytoskeletal elements of the cell (i. e. actin filaments). When the cell is put under stress, the cytoskeletal elements pull on the channel and changes it shape allowing it to open: ligand-gated channel: ligand binds at a receptor site on the channel. Channels can prevent equilibrium by closing, preventing diffusion, but when they are open, channels always allow molecules to flow down their electrochemical gradient. Additionally, there is a binding site for atp on the transporter.