A glucose molecule binds to a transporter protein in the cell membrane. What happens next in facilitated diffusion?

• A. The transporter protein forms a permanent tunnel for glucose to pass through.
• B. The transporter protein undergoes a conformational change to move the glucose across the membrane.
• C. The transporter protein uses ATP to move the glucose across the membrane.
• D. The glucose molecule diffuses directly through the lipid bilayer.

Answer: (B)