Chapter 34, Problem 5Q

Summary Introduction

To review:

The role of aquaporins in the uptake of water from the soil by root cells.

Given:

The oocytes of the frog Xenopus laevis were taken by the researchers and injected with the messenger ribonucleic acid (mRNA) of plant tonoplast intrinsic protein (TIP). They are large in size and have a low osmotic cell permeability. The, mRNA of a nontransport protein is taken in the second case and injected into the oocytes. Some of the oocytes were not injected at all and this became the third case of the experiment. These cells were observed after giving incubation of 2 days in isotonic medium and a treatment with hypotonic solution. The following graph was made by plotted changes in relative volume on the y-axis and time on x-axis:

The oocytes which had TIP mRNA burst after sometime while the oocytes, which were injected with a different nontransport protein, and the oocytes which were not injected do not burst. The following table depicts the osmotic water permeability of the three conditions as calculated by the researchers:

Introduction:

Aquaporins are the integral membrane proteins which are responsible for the transport of molecules of lower weight across the bilipid layer. They transport across the concentration gradient and does not require energy.