Question

Assume that the import of a particular amino acid across the plasma membrane is observed to occur only down its concentration gradient and to slow when a different but similar amino acid is added to the extracellular fluid. The movement of the amino acid through the membrane is most likely by:____________

Answer 1

Answer: facilitated diffusion

Explanation:

The facilitated diffusion is a process through which the passive transport of ions and molecules takes place across the biological membrane through specific transmembrane integral proteins.

This process allows the diffusion of the charged molecules like aminoacids, ions and nucleosides to cross the plasma membrane.

On the basis of the above description, facilitated diffusion is the process by which the amino acids will move along across the concentration gradient.

Answer 2

Answer:

facilitated diffusion

Explanation:

In facilitated diffusion, certain transport proteins of membranes (channels and carriers) serve in transport of the substances across the membrane. The movement of the amino acid occurs down the concentration gradient only. In facilitated diffusion, transport of substances occurs from the region of their higher concentration to that of the lower concentration. It is a passive process. The addition of some other amino acid slows down the transport of the first amino acid due to the saturation effect. All the transport proteins that facilitate the diffusion of amino acids across the membrane become occupied. This slows down the transport of the amino acid.