Biology Beetroot Lab Report

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Investigating Effects of duration of heating on permeability of beetroot cell membrane

Introduction: Cell membranes contain many different types of molecules which have different roles in the overall structure of the membrane. Phospholipids form a bilayer, which is the basic structure of the membrane. Their non-polar tails form a barrier to most water soluble substances. Membrane proteins serves as channels for transport of metabolites, some act as enzymes or carriers, while some are receptors. Lastly carbohydrate molecules of the membrane are relatively short-chain polysaccharides, which has multiple functions, for example, cell-cell recognition and acting as receptor sites for chemical signals.

The plasma membrane is a permeable membrane. An important role of the plasma membrane is to maintain the integrity of the cell, holding the cell contents together. Membrane permeability is a quality of the cell’s plasma membrane which allows certain substances to pass while forming a barrier against others, controlling exchanges between the cell inner and outer environment. Substances passed inside include for instance, water, respiratory gases like oxygen and carbon dioxide, nutrients such as glucose and essential ions. On the other hand, waste products can be expelled and components required to assemble cell walls can be secreted out through the membrane.

Because of the permeability of the plasma membrane, cells can extract the amino acids, fatty acids, sugars and vitamins need to carry out its daily functions. The movement across the plasma membrane of living cells is continuous and sustains the cells.

Beetroot is a vegetable that contains a rich source of potent antioxidants and nutrients which is important for cardiovascular health. Betacyanin, a red pigment, can be obtained in the vacuole of beet root cells, and is commonly used industrially as red food colourants or ink. In exploring the permeability of a beetroot membrane which contains a coloured pigment, additional research was conducted regarding light and the optical spectrum. The visible spectrum of light is the portion of the electromagnetic spectrum which is visible to the human eye. The human eye would respond to wavelengths from approximately 390nm to 750nm. A colorimeter can be used to measure the absorbance of specific solutions at a particular wavelength of light. Colorimeter is an instrument that compares the amount of light getting through a solution with the amount that can get through a sample of pure solvent. A colorimeter contains a photocell which is able to detect the amount of light which passes through the solution. Results from the colorimeter can be read as absorbance and % transmittance outputs. (Source: http://www.wisegeek.com/what-is-a-colorimeter.htm)

Despite all attempts of movement of substances in and out of the membrane to sustain the cell, conditions can be manipulated leading to the malfunctioning of the cell, disrupting its phospholipid bilayer. Examples of conditions include heat, coolness, and use of detergents and solvents.

In conclusion, this investigation will have a focus in the condition of heat. It will explore the effects that the duration of heating a beetroot has on the permeability of its cell membrane.

Research Question: How do the different durations that the beetroot is heated for affect the permeability of the beetroot membrane?

Aim: The aim of this experiment is to determine whether the different durations of heating a beetroot would affect its membrane permeability. This would be done by changing the amount of time of which the beetroot sample is heated, and measuring its % transmittance of light. Using the data collected, I would determine the permeability of the beetroot membrane under heating conditions.

Hypothesis: I predict if the beetroot sample is heated for a longer period of time, the permeability of the beetroot membrane should increase. This is because when the beetroot sample is...
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