Candidate Name: Yupeng Wu(Juanita)
Candidate Number: 049151-0059
Date of practical: Nov 24th.
Investigating the Relationship Between the Concentration of Ethanol and the Rate of Diffusion of Betanin Pigment in Beetroot Cell Membranes
Research Question
How does different concentrations of ethanol(100%, 50%, 25%, 12.5%, 6.25%) affect the rate of diffusion of betanin pigment(determined by colorimeter) in beetroot cell membranes?
Introduction
Beetroot contains a pigment called betanin, which is water-soluble. The betanin pigment is located in the large central vacuoles of beetroot cells, which are selectively permeable. Under normal condition, the betanin pigment molecule is too large to pass through the selectively permeable membrane. So if…show more content… The beetroot samples of the same size will be soaked in different ethanol solutions for the same amount of time. The color intensity of each solution will then be determined using a colorimeter.
Hypothesis
Ethanol damages the plasma membrane of the beetroot cell. When the plasma membrane is damaged, more betanin molecules are allowed to pass through the membrane, giving the solution a pink color. The intensity of color should be proportional to the amount of cellular damage in the beetroot. Thus, the higher the concentration of ethanol, the higher level of cellular damage, the higher the color intensity(absorbance).
The rate of diffusion is the change in absorbance over a specific amount of time.
Rate of diffusion, r =
So my hypothesis is that the higher the concentration of ethanol, the higher level of cellular damage in the beetroot cell, the higher the color intensity(absorbance), the higher the rate of diffusion.
Variable
Dependent Variable:
-the rate of diffusion of betanin pigment in beetroot cell membranes (by colorimeter)
Preparing Beetroot Strands
Cut the beetroot into strands of the same size(0.2 cm×0.2 cm×1.0 cm) using a scalpel.
Wash the strands using distilled water to remove the excess red dye left on the surface
Trials
Add one strand of beetroot to each test tube and gently mix the contents in the test tubes
Soak the strands in ethanol solutions for an hour.
When the time is up, pour the solutions into cuvettes. Fill each cuvette 3/4 full.
Connect to the colorimeter and prepare the computer for data collection.
Calibrate the colorimeter. -open the colorimeter lid -hold the blank cuvette by the upper edges, place it in the cuvette slot of the colorimeter -close the lid -press the “ or “ button on the colorimeter to select a wavelength of 470 nm (blue according to the instruction) for this experiment. -press the CAL button until the red LED begins to flash, then release. When the LED stops flashing, the calibration is complete.
6. Collect absorbance data -click “collect” -wait for absorbance value displayed in the meter to stabilize -click “keep”, enter 0 in the edit box and then press
