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Why does the colour leak out of cooked beetroot

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Why does the colour leak out of cooked beetroot? Aim: To use beetroot to examine the effect of temperature on cell membranes and relate the effects observed to membrane structure.redistribute Objective: To immerse beetroot for a constant period in water at varying temperatures. Hypothesis: An increase in temperature will damage and denature the membrane and cause the substances contained within it to leak out. Introduction: The purpose of a cell membrane is to control the transport of substances moving into and out of a cell. The membrane is an extremely thin layer (8 to 10 manometers (nm)) thick, which is partially permeable. It consists mostly of lipids and proteins. The lipids found in cell membranes belong to a class known as triglycerides, so called because they have one molecule of glycerol chemically linked to three molecules of fatty acids. The majority belong to one subgroup of triglycerides known as phospholipids. Despite their many differences in appearance and function, all cells have a surrounding membrane enclosing a water-rich substance called the cytoplasm. All cells host a variety of chemical reactions that enable them to grow, produce energy, and eliminate waste. Together these reactions are termed metabolism. ...read more.


Cell wall: cell wall. Plasma membrane: envelope of plasma. Thylakoids: membranous molecular structures involved in photosynthesis. Starch grain: starch granule. Experiment Material: * Raw Beetroot * Size 4 Cork borer * White tile * Sharp Knife * Ruler * Beakers with water at 20, 30, 40, 50, 60, 70, 80 oC temperatures. * Plastic Beaker, about 250cm3 * 2 boiling tube racks * 8 boiling Tubes * Thermometer * Colorimeter * Stopclock * Distilled Water * Pipette for measuring 7cm3 * Bunsen Burner * Mounted Needle * Bunsen Burner stand * Small Measuring Cylinders Method: * Cut sections for a single beetroot using the cork borer (from the same beetroot each time). Take off the skin at both ends of beetroot cylinder. Cut 7 3mm length slices from these sections using a ruler and knife.( cut on white tile) * Wash off the excess purple pigment on the surface of the beetroot discs. (Wash under sink for 1 minute). * Load a mounted needle with 7 equal sized beetroot discs * After this 1 minute, place a labelled boiling tube containing 7cm 3 of distilled water on a test tube rack. ...read more.


Conclusion: After collecting and correlating the results, I have come to the conclusion that the hypothesis is correct in that an increase in temperature will damage and denature the membrane and cause the substances contained within the membrane to leak out. This has been shown by a steady increase in anthocyanin leaked out of plant cells measured by the colorimeter light absorbance, as the temperature increases. There is almost certainly an amount of experimental error. It is the breakdown of the lipids which make up the membrane that causes 'holes' to appear in the membrane, allowing fluids to pass out freely, but when the temperatures begin to get higher still, the proteins in the cells begin to decompose as well which blocks some of the holes and therefore slowing down the release of anthocyanin. Evaluation: It is safe to say that the results have been repeated reliably however it still would have been beneficial to have repeated the experiment more times to make certain that the results were not gained through chance or by an external factor. The control experiment used was highly accurate, using distilled water, which is the clearest possible liquid, meant that even the slightest deviation in colour could be detected by the colorimeter. , we can say that whilst this represents a progression, in the end we have come no closer to any "real" knowledge. ...read more.

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