Protein Channels
Leak channel (Passive channel).
In what direction do solutes move during diffusion?
From low to high concentration
What do we call a molecule that binds to a receptor?
A ligand.
What kind of molecules can undergo simple diffusion?
Water, O2, CO2, and lipid-soluble/non-polar molecules.
What kind of channels are opened by adding or removing a phosphate?
Phosphorylation/dephosphorylation-gated channels
How are hydrophilic molecules and ions moved down their concentration gradient?
Facilitated diffusion.
What kind of membrane protein helps attach a cell to other nearby cells?
Cell adhesion protiens.
Does facilitated diffusion require energy?
No.
What kind of channels require receptors?
Ligand-gated channels.
What happens when a molecule binds to a membrane carrier protein?
The carrier changes shape and releases the molecule into the cell.
In what system do cell surface identity markers play an important role?
The immune system.
What is the difference between a symport and an antiport?
Symports move two molecules in the same direction, antiports move two molecules in opposite directions.
Voltage-gated channels open and close in response to what?
Local changes in membrane potential.
True or False: any molecule can pass through an open channel, as long as it is moving down its concentration gradient.
False.
What is the difference between a carrier protein and a protein channel?
How would increasing the thickness of a membrane affect the rate of diffusion?
Decrease the rate of diffusion
What causes a mechanically gated channel to open?
Stretching or pulling forces/distortion of the plasma membrane.
How would increasing the concentration difference across a membrane affect the rate of diffusion?
It would increase the rate of diffusion
Protein channels are selective and select/filter for which molecules they transport using what two criteria?
Size and charge.
How would decreasing the surface area over which diffusion is taking place change the rate of diffusion?
It would decrease the rate of diffusion.