Answer to Question #113893 in Biology for Shayna

Question

There are many modes of cellular transport across the plasma membrane. Which of these do not require the use of ATP?

Answer 1

Passive transport is the transfer of substances from a region of high concentration to a region of low energy without ATP. There are two types of membrane transport without the use of ATP: simple diffusion and facilitated diffusion. During simple diffusion, particles of a substance move through a lipid bilayer. The direction of simple diffusion is determined only by the difference in the concentrations of the substance on both sides of the membrane. Hydrophobic substances (O₂, N₂, benzene) and polar small molecules (CO₂, H₂O, urea) penetrate the cell through simple diffusion.

Facilitated diffusion is associated with the transfer of substances are using transport proteins (carrier proteins) located in the cellular membrane. Polar substances (amino acids, monosaccharides), charged particles (ions) pass through membranes with the help of facilitated diffusion with the participation of channel proteins or carrier proteins. Carrier proteins provide a higher rate of facilitated diffusion compared to simple passive diffusion.