How Temperature Effects the Movement of Pigment Through Cell Membranes

How Temperature Effects the Movement of Pigment Through Cell Membranes

Abstract

The experiment below displays the effects of temperature on the

pigment in uncooked beetroot cells. The pigment in beetroot cells lies

within the cell vacuole and is called anthocyanin, each vacuole is

surrounded by a tonoplast membrane and outside it, the cytoplasm is

surrounded by the plasma membrane, therefore the foundation of this

experiment lies with the temperature at which the membranes will

rupture and therefore leak the pigment. To do this a series of

uncooked beetroot cylinders will be exposed to different temperatures

and then to distilled water at room temperature (24ºC). The colour of

the distilled water is the variable here which will show us, using a

colorimeter what temperature the membranes splits using the

transmission of the water (light passing directly through and the

absorbency (light getting absorbed by the anthocyanin molecules).

Introduction

Within the cells of a beetroot plant, a pigment is held within the

vacuole of a beetroot cell, this pigment gives the beetroot its

red/purple colour. If a cell is damaged or ruptured in a beetroot and

the cell surface membrane ruptures, the pigment 'drains' from the

cells like a dye. It is this distinction that can be employed to test

which conditions may affect the integrity of the cell surface

membrane. The pigments are actually betalain pigments, named after the

red beetroot (beta vulgaris) it breaks down at about 60ºC. They

replace anthocyanins in plants. Unlike anthocyanins, betalains are not

pH indicators, i.e. they do not change colour when the pH is lowered.

Beetroot pigments are unstable at high temperatures, but the chemistry

depends on a number of variables. Including the pH and composition of

the solution, oxygen concentration and how long the solution is

heated. However for the cell membranes an increase in temperature

weakens the structure, just as the decrease in temperature decreases

membrane fluidity until death, the increase in temperature does

likewise until the membrane ruptures by the phospholipids breaking

down to produce holes in the membrane, this is what will release the