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Chapter 5: Problem 5

Explain why active transport of an ion shows saturation kinetics, whereas transport of an ion through an ion channel does not.

Short Answer

Expert verified
Active transport shows saturation kinetics because it involves carrier proteins that can become fully occupied, limiting the rate of transport, no matter how high the ion concentration gets. In contrast, ion channels do not exhibit saturation kinetics because they are not limited by a finite number of carriers. The rate of transport can continue to increase as the ion concentration increases, until equilibrium is reached.

Step by step solution

01

Define Active Transport

Active transport is a process where ions are moved across the cell membrane against the concentration gradient, from an area of low concentration to high concentration. This process requires energy, which is usually obtained from ATP (Adenosine Triphosphate).
02

Define Ion Channels

Ion Channels, on the other hand, allow ions to move down their concentration gradient from an area of high concentration to one of low concentration. This process is passive and doesn't require energy. These channels work more like pores and are selective for certain ions.
03

Explain Saturation Kinetics

Saturation kinetics refers to the point at which increasing the concentration of ions (or substrate) doesn't increase the rate of transport (or reaction). This happens because all the carriers (or enzymes) are occupied at high substrate concentration. In the context of active transport, this means that there is a maximum rate at which ions can be transported, regardless of how high the ion concentration gets in the extracellular fluid.
04

Explanation of the Difference in Saturation

Active transport of ions shows saturation kinetics because there is a finite number of ion carriers available. When these are all in use, no matter how much the ion concentration increases, the rate of transportation cannot increase. On the contrary, transport of ions through an ion channel doesn't show saturation kinetics. This is because ion channels are not limited by a finite number of carriers. The rate of transport can continue to increase as the ion concentration increases, until the concentration gradient is equal on both sides.

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Most popular questions from this chapter

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