Investigating Membrane Permeability
Reason for choosing beetroot as the object of experiments
Beetroot is usually used as the membrane ‘disruption’ experiment. It is because of beetroot has more pigments in their vacuole. These pigments show how variables damage the membrane of beetroot. The pigments will be automatically extracted from the vacuole when the membrane is broken. More damages at plasma membrane, more pigments will be extracted.
In many plants that give beautiful colour, their vacuole contains anthocyanin. Anthocyanin is a water-soluble vacuolar pigment that gives a plant, blue or red or purple according to pH. But in beetroot, it is not anthocyanin, but betalain. Like anthocyanin, but we can say that Betalain is ‘replacing’ anthocyanin in Caryopyllales plants’ vacuole(e.g beetroot plant). But the contrast difference is, Betalain pigment is not pH indicator. It has stable colour in the range of pH.
Back to the topic, the objective of this experiment is to ‘extract’ the pigment from the vacuole. To make it to be extracted, the membrane must be disrupted before. Like what I said before, when the membrane is disrupted, the pigments in the vacuole will be automatically extracted. It is because of, when the membrane is broken, it’ll make like a hole, that will ‘twist’ the vacuole, as the vacuole is twisted, it will make the vacuole leaks gradually. When the vacuole is leaked, the pigments will be extracted. To make the membrane disrupted, we can apply heat shock, or detergent, or organic solvent, or acidity (pH).
In this experiment, the writer only used three variables, they are ; temperature or heat, pH or acidity condition, and detergent. And after this page, the writer will explain the result and analyse.
To predict how temperature damages the beetroot membrane Background:
In the previous page
3 Cutted beetroot
15 ml fresh water (each in test tube)
2 Bunsen burners
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