Lab 2e- Variation of Structure and Characteristics of Carbohydrates
September 5, 2014
Purpose: The focus of this lab is to identify differences in structure, taste, and texture between common carbohydrates, sugars. After gathering observations, the purpose is to determine the ways the structure changes the properties of the carbohydrates.
Pictures: The slide show to the right displays the chemical structures of the eight different sugars that will be tested in this lab. The order of pictures is identical to the order of the carbohydrates listed in the materials section.
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Materials: Petri-dishes(60 x 15 mm, sterile), Plastic spoons, Paper cups, Tap water, Sugars(Sucrose, Glucose, Fructose, Galactose, Maltose, Lactose, Cellulose, Starch)
Because we dealt with D-glucose, here is another joke: A person accidentally ingested some alpha L-glucose and discovered he had no ill-effects. Apparently he was ambidextrous.
Because we dealt with D-glucose, here is another joke: A person accidentally ingested some alpha L-glucose and discovered he had no ill-effects. Apparently he was ambidextrous.
Hypothesis: If each sugar has a more complex molecular structure, then the taste will be different and sweetness will be less because the carbohydrate will be more difficult to break down. Because he arose to a breader position and became superior.
Procedure Part One: The first part of the experiment was to research the structure and function of each molecule being tested. The pictures above show the chemical structure of each sugar. Below(on the chart) is the descriptions for the purpose of each carbohydrate. The next portion of the lab included taste testing each of the substances and observe similarities of color and texture. Pour every sugar onto different sections of a paper towel and label each group the appropriate title. Use a finger to gather a slight amount of the carbohydrate to taste; use a different finger for a second trial to protect against germs and cross contamination. Record observations and level of sweetness for each sugar in the table below.
Characteristics of Various Carbohydrates
Carbohydrate
Sucrose Glucose(dextrose) Fructose Galactose Maltose Lactose Cellulose Starch |
Type of Carbohydrate
Disaccharide Monosaccharide Monosaccharide Monosaccharide Disaccharide Disaccharide Polysaccharide Polysaccharide |
Sweetness
50 75 90 40 20 10 0 5 |
Color
White White Gray/White White White White Beige/Light yellow Creamy White |
Texture
Granular Granular Soft/Granular Granular Grainy Powder Soft Powder Rough Powder/Sawdust Soft Powder(sticks together) |
Functions
Energy, Transport Energy Energy Energy/Structure Digests Starch Energy Structure(plants) Stores food, Structure |
*Scale: 0 to 100. Zero is the least sweet and 100 is the sweetest. Sucrose was a baseline test for the midpoint(50).
Conclusion: From tasting different carbohydrates, we discovered that the chemical structure of the molecule changes the properties of the substance. My hypothesis was correct because the polysaccharide carbohydrates tasted terrible compared to the carbs with only one sugar ring. For example, the less amount of sugar rings, the sweeter the carbohydrate is. Both Fructose and Glucose only have a single sugar ring and these two sugars were definitely the sweetest. The amount of sugar rings also affect the texture and color. The augment of rings creates the carbohydrate to become softer and powdery, like cellulose and starch. The polysaccharide carbohydrates are a murkier white or beige color. The structurally similar carbohydrates had several similar components. For example, the monosaccharide carbohydrates are used for energy and they taste sweeter. These sugars are also more granulated and look like a cleaner white color. The polysaccharide carbohydrates serve the purpose of structure in a cell and they have a more bitter taste. The disaccharide carbohydrates are a median for the taste and the physical aspects of each sugar varies. Luckily, each person in my group agreed on the level of sweetness, but these results could be affected by several different things. Different people have different taste buds that could give various results. Another issue could be cross contamination between sugars because people may not have rinsed their mouth or used a different finger for each sugar tested. The quantity of sugar tasted could also give a more intense taste and would provide a varying opinion.
Reflection: Overall, this experiment was very successful. One positive aspect was the conclusive data. Human error was not as prevalent because my group was very careful about separating and distinguishing each group of sugars clearly. Another good part about our lab was the organized work station. Due to the lack of messy materials and unneeded writing supplies, our work table required simple cleaning up and we kept our notebooks mysterious substance free. However, there was also a couple of negative parts to my group. First of all, not everyone at our table was willing to try all the carbohydrates so instead of having three opinions to contrast, we only had one or two. This was not a major issue, but it could be more helpful in the future to receive accurate data. Another issue I had was the multiple tastes overlapping each other. After each trial, no one in my group rinsed out their mouth so towards the end it was challenging to differentiate the sugars because it all tasted similar.