Absorbency Values Of The Betacyanin Solutions example essay topic

Measuring the Absorption of 525 nm Light into Stock and Leaked Betacyanin Solutions Created from Beet Root Discs Which Vary in Concentration Introduction: The Pigment Betacyanin is a pigment located in the large central vacuole of a beet cell. These vacuoles are surrounded by a membrane called the tonoplast and are located in the cytosol of the cell. Surrounding the cell is another membrane called the plasma membrane. Under normal conditions these two membranes remain intact. However when the membranes are damaged betacyanin leaks from the vacuole creating a red colour in the water in which the beet root disc is immersed.

The objective of this study is to subject beet root discs to various temperatures and analyse the amount of damage done to the cells. This is achieved by measuring the amount of betacyanin that leaks from the cells. Since betacyanin is a pigment, it is capable of absorbing (525 nm) light in amounts that are directly proportional to the concentration of betacyanin leaked from each treated beet disc that is now in solution. A standard curve will be created using a stock solution of betacyanin and used to quantify the concentration of leaked betacyanin. It is believed that as extra-cellular temperature becomes more extreme, thermal damage is done to the tonoplast and plasma membranes or the beet disc cells. As a result, betacyanin will leak from the cells and therefore produce a higher absorbency value when exposed to 525 nm light.

This study was conducted because it is important in the process of understanding the effects of external conditions on the membranes of cells. It is vital that biology students understand the content of this lab and its relevance with regards to all cell membrane structures. Materials and Methods: The biology 107 lab manual (2003) stated that a standard curve related the concentration of betacyanin solution and absorbency of 525 nm light. This was achieved by making stock solutions of betacyanin in test tubes which vary in concentration then placing tubes and analysing their absorbency in a spectrophotometer. Biology 107 lab manual also states that students were required to expose seven beet root discs to various temperatures for a common period of time then place the discs in a test tube filled with distilled water. After a predetermined period of time, analysis of the absorbency for each respective test tube in the spectrophotometer was done to conclude the trend for the amount of betacyanin released in relation to exposed temperature.

Note that a 1: 10 betacyanin to distilled water solution was created in the test tube for the -5 ^0 C treatment and a 1: 5 betacyanin to distilled water solution was created for the 70 ^0 C solution. These were two changes made to the method which was stated in the biology 107 lab manual. Results: The stock betacyanin solutions (control group) produced absorbency values in the spectrophotometer which decreased as the betacyanin solution concentration decreased. For example, the 4.0 micro mole per litre concentration of betacyanin solution had an absorbency value of 0.465 in 525 nm light. The 2.0 micro mole per litre concentration of betacyanin solution had an absorbency value of 0.230 in 525 nm light.

For complete control group results refer to graph number one. Similarly, the absorbency values of the betacyanin solutions decreased as the concentration of each solution decreased for the actual beet root discs (experimental group) that were exposed to various temperatures. Note that higher concentrations of betacyanin were present for beet root discs which were exposed to more extreme temperatures. For example, the -5 ^0 C treatment yielded an absorbency value of 0.21 when exposed to 525 nm light and a betacyanin concentration of 18 micro moles per litre. The 25 ^0 C treatment yielded an absorbency value of 0.015 and a betacyanin concentration of 0.15 micro moles per litre.

For complete experimental group results refer to graph number two. Discussion: As stated earlier, it is believed that as the tonoplast and plasma membranes of beet root discs are subjected to more extreme temperatures, damage is done to each respective membrane, and greater amounts of betacyanin pigment would leak from the beet cells. Thus by analysing our results it was evident that a trend was present with regard to the amount of betacyanin absorbency in relation to more drastic temperatures. The -5^0 C treatment and the 70^0 C treatments were the most extreme temperatures to which the beet discs were subjected and therefore caused the greatest amount of betacyanin leakage and as a result, a higher absorbency value of 525 nm light. It is evident that our results support the hypothesis stated earlier due to the fact that the highest absorbency values recorded were for the more drastic temperatures.

Specifically, the -5^0 C treatment had an absorbency value of 18 in 525 nm light and the 70^0 C treatment had a value of 2.5 in 525 nm light. These values of absorbency are large compared to the other treatments which ranged from 4^0 C to 55^0 C and had absorbency values no larger than 0.2. As a result of the higher absorbency values being present only for the extreme temperatures, it can also be inferred that at these temperatures the most cell membrane damage was done which initiated the release of the greatest amounts of betacyanin. The experimental design used in this biology 107 lab is valid as it involves a standard curve to calculate the concentration of betacyanin for each temperature treatment and also the length of treatment was kept constant for each temperature. Minimizing the amount of variance in this experiment aloud our results to be consistent and reliable.

The effect that a change in extra-cellular condition has on cell membrane permeability was also shown in an experiment where a cell was put in contact with Epsilon toxin. The Epsilon toxin formed wide and water-filled channels in the membrane which were permeable to hydrophilic solutes (Petit et al., 2001). Similar to the effect of increasing or decreasing temperature, the toxin increased the permeability of the cell membrane and as a result made it easier for substances to pass through it. A similar study was conducted in which brain mitochondria cells were exposed to dopamine, 6-hydroxy dopamine (6-O HDA), and MPP+.

Much like the Epsilon toxin and temperature, these external condition changes increased the permeability of the brain mitochondria cells (Chung Soo Lee et al., 2002). Tests were also done on the effected cells in this experiment which were comparable to those done in class on the beet disc cells. For example, the brain mitochondria had measurements taken which analysed their degree of permeability change. Using a spectrophotometer, this was accomplished by measuring the absorbency of various wavelengths of light into the cells after it was subjected to different assays and ions.

Mitochondrial swelling, membrane potential, calcium transport, and cytochrome c release are some examples of permeability change.