Certain integral membrane proteins facilitate the diffusion of molecules across the membrane without directly binding to the transported molecule. These proteins create a continuous aqueous pathway through the lipid bilayer. Which of the following is the BEST example of such facilitated diffusion?
GLUT transporters moving glucose
Sodium-potassium pump maintaining ion gradients
Aquaporins transporting water
Chloride channels gated by voltage
Related Questions
Which type of molecule is LEAST likely to cross a cell membrane by simple diffusion?
Small, nonpolar molecule
Small, polar molecule
Large, polar molecule
Small, uncharged molecule
In facilitated diffusion, the carrier protein:
Hydrolyzes ATP to move the molecule
Undergoes a conformational change to transport the molecule
Forms a channel that remains permanently open
Transports molecules against their concentration gradient
What happens to the rate of facilitated diffusion as the concentration of the transported molecule increases?
It increases linearly
It decreases
It reaches a maximum rate (saturation)
It remains constant
An example of facilitated diffusion is the transport of:
Oxygen across the cell membrane
Carbon dioxide out of cells
Glucose into cells
Water through aquaporins
Facilitated diffusion is different from simple diffusion because it:
Moves molecules against the concentration gradient
Uses carrier proteins
Requires ATP
Occurs only in plant cells
