An Investigation into the Properties of All Membranes in Beetroot Cells

An Investigation into the Properties of All Membranes in Beetroot Cells

Aim

This experiment aims to investigate what effect temperature has on the release of pigments through the membrane of a beetroot using a colorimeter.

Introduction

Beetroot is a plant; therefore it is made up of plant cells. Plant cells have a cell wall that is made up of cellulose; this is a complex carbohydrate that is composed of glucose units. Cellulose forms most of the cell structure and shape.

Within the cell wall is the phospholipid bilayer (plasma membrane). This bilayer is partially permeable and has intrinsic proteins on its inner surface and extrinsic proteins on its outer surface. These proteins are involved in the attachment of materials.

If the plasma membrane were to be damaged in any way, for example by heat, then you are disrupting the protein structure and the cell becomes denaturised. The fatty acid tails (hydrophobic chains) within the bilayer will break down allowing the passage of unwanted materials such as water.

Inside the plasma membrane is the jelly-like substance known as Cytoplasm. All cell organelles are found in the cells cytoplasm.

The largest organelle in a plant cell is the vacuole, making up around 70% of the cell. The vacuole is a fluid filled sack that is surrounded by a single membrane. The membrane is made of tonoplast. The fluid in the vacuole contains a solution of mineral salts, organic acids, waste and pigments and this can change in volume and affect the shape of the cell by exhorting hydrostatic pressure.

In a beetroot cell, the pigments that are contained in the vacuole are called betalain and this is red in colour. If the cell is denaturised, this red pigment is released from the cell. To measure the amount of pigment that is being released changes have to be made to its surrounding environment. This can be done by controlling variables.

By changing and controlling an independent variable such as temperature, it allows for the released pigment (dependant variable) to be measured more accurately.

By heating beetroot cells in a water bath set at three different temperatures, the released pigments can be measured and recorded in a results table and graph to see if there is any correlation.

Hypothesis

The bath at the hottest temperature of 60 degrees Celsius will cause the beetroot membrane to release more pigments than the baths with the lower temperatures of 40 and 60 degrees Celsius.

Method

The apparatus used for this experiment were as follows:

1x goggles (P.P.E)

1x laboratory coat (P.P.E)

3x water baths

2x tube racks

9x boiling tubes

9x test tubes

1x whole beetroot

1x tile

1x cork borer

1x scalpel

1x forceps

1x conical flask

1x sieve

1x bottle of distilled water (room temp)

1x graduated cylinder

10x cuvettes

1x colorimeter

The experiment was done in a step by step order as follows:

1. Firstly it was ensured that Personal Protective Equipment (PPE) was worn at all times. The laboratory coat and goggles were on correctly, long hair was tied up and any loose clothing and/or jewellery were removed.

2. Nine boiling tubes and nine test tubes were set up in separate racks along with three water baths that were filled and set to 20, 40 and 60 degrees Celsius, preparing them for later use.

3. A whole beetroot was peeled by hand and placed on a tile.

4. The cork borer was then used to cut through the beetroot, giving an accurate cylindrical sample. The metal rod was then used to remove the sample from the cork borer leaving a 4mm tube of beetroot.

5. This cork borer method was repeated giving the experimenter two identical tubes.

6. The two tubes were then sliced into eighteen thin discs using the scalpel, ensuring they were all of similar thickness for a more accurate result.

7. Using the forceps, the samples were placed into a conical flask and rinsed for an estimated time of five minutes under cold water. This was done to ensure any cell debris and leaked pigment had been removed.

8. After this five minutes the contents of the conical flask were drained using a sieve making sure no samples were lost.

9. Then using forceps the discs were separated equally into the nine boiling tubes that were previously prepared, thus giving each tube two samples.

10. Each of the boiling tubes was then given 10cm cubed of distilled water. This was accurately measured using a graduated cylinder.

11. These tubes were then divided into three lots of three and placed into the pre prepared baths, giving three tubes for every one bath. The tubes were left in these baths and timed for thirty minutes.

12. During this thirty minutes a cuvette was filled with distilled water (to the marker) and placed in the colorimeter to calibrate the machine.

13. Once the thirty minutes was up, the boiling tubes were removed from the baths one at a time and the liquid was transferred into the nine clean test tubes, leaving the beetroot behind.

14. These were then labelled in correspondence to the bath they came from.

15. Finally the test tubes were individually poured into separate cuvettes and placed into the colorimeter one at a time to gain the pigment reading.

Results

Singular findings:

Temperature Test 1 Test 2 Test