Detection of Biological Molecules
Introduction: Without carbon, nitrogen, hydrogen, sulfur, oxygen and phosphorus, life wouldn't exist. These are the most abundant elements in living organisms.
These elements are held together by covalent bonds, ionic bonds, hydrogen bonds, and disulfide bonds. Covalent bonds are especially strong, thus, are present in monomers, the building blocks of life. These monomers combine to make polymers, which is a long chain of monomers strung together. Biological molecules can be distinguished by their functional groups. For example, an amino group is present in amino acids, and a carboxyl group can always be found in fatty acids.
The groups can be separated into two more categories, the polar, hydrophilic, and the nonpolar, hydrophobic. A fatty acid is nonpolar, hence it doesn't mix with water. Molecules of a certain class have similar chemical properties because they have the same functional groups. A chemical test that is sensitive to these groups can be used to identify molecules that are in that class. This lab is broken down into four different sections, the Benedict's test for reducing sugars, the iodine test for the presence of starch, the Sudan III test for fatty acids, and the Biuret test for amino groups present in proteins. The last part of this lab takes an unknown substance and by the four tests, determine what the substance is.
BENEDICT'S TEST
Introduction: Monosaccharides and disaccharides can be detected because of their free aldehyde groups, thus, testing positive for the Benedict's test.
Such sugars act as a reducing agent, and is called a reducing sugar. By mixing the sugar solution with the Benedict's solution and adding heat, an oxidation- reduction reaction will occur. The sugar will oxidize, gaining an oxygen, and the Benedict's reagent will reduce, loosing an oxygen. If the resulting solution is red orange, it tests positive, a change to green indicates a smaller amount of reducing sugar, and if it remains blue, it tests negative.
Materials: onion juice 5 test tubes 1 beaker potato juice ruler hot plate deionized water permanent marker&nb... ... middle of paper ...
...cedures: 1. Performed the Benedict's Test, and recorded results. 2.
Performed the Iodine Test, and recorded results. 3. Performed the Sudan III
Test, and recorded results. 4. Performed the Biuret Test, and recorded results.
Data: Properties of Chemical #143
chemical #143 was a white powderish substance.
Conclusion: After ruling out the obvious wrong substances from the list like ground coffee, egg white and yolk, table sugar and salt, syrup and honey, the small amount of proteins was taken into factor. That also eliminated powdered skim milk, and soy flour. The low, or none fat content ruled out some more choices like enriched flour. The only choices left was corn starch, glucose, and potato starch. Because of the low reducing sugar, glucose can be ruled out also. The starch content of substance #143 was very high. The protein content was around the 10% range, so potato starch would be a better guess then corn starch.
But corn starch contained only a trace of fat when potato starch contained 0.8%.
But 0.8% is very insignificant. The most educated guess to what chemical #143 is potato starch.
When the solution remains the same, it means the solution is negative control and does not have sugar. The presence of starch can be detected by using the Lugol’s iodine solution. If the unknown A, B, C milk samples turn to a dark blue color during the Lugol’s test, then these samples are positive control and also contain starch in them. But if the solutions turn to yellowish brown, it means these solutions are negative control
According to Sara Florine, “Starch, which is a complex carbohydrate composed of glucose molecules bound together, is a major component of [corn]” (Florine). Thus, the Lugol’s test came back “black” or positive. Furthermore, the results can be backed up by the nutrition label on a Chex cereal box, which has corn listed as one of the main ingredients in the cereal, which is a strach. (EWG’S Food Scores) Additionally, according to the Environmental Working Group, Chex cereal is also made with and processed with corn oil. (EWG’S Food Scores). It is a small amount of oil, but nonetheless its enough to make the Beta Carotene test come back positive for
The independent variable for this experiment is the enzyme concentration, and the range chosen is from 1% to 5% with the measurements of 1, 2, 4, and 5%. The dependant variable to be measured is the absorbance of the absorbance of the solution within a colorimeter, Equipments: Iodine solution: used to test for present of starch - Amylase solution - 1% starch solution - 1 pipette - 3 syringes - 8 test tubes – Stop clock - Water bath at 37oc - Distilled water- colorimeter Method: = == ==
I blended on high to make the potatoes more liquid-like. I grabbed the cheesecloth and placed on the top of the blender. I poured the potato extract on the container and labeled it. I found out that I have to make 1% sugar solution so I grabbed the sugar and measured into 5 grams on the scale. I added 5 grams of sugar on 250 ml graduated cylinder and poured the water into the cylinder. I mixed the sugar with water and poured it into the saucepan. I refilled the water into the graduated cylinder and poured into the saucepan. I turned on the heat of the stove and saw the sugar dissolved. I poured into a container and labeled 1% sugar solution. I repeated the same thing with 1% salt solution by using 1 gram of salt and filled the water into graduated cylinder by 100 ml. I answered question three. In the first experiment, I grabbed four transfer pipets and used it to put solutions into the test tubes by 3ml. I labeled it and placed into the plastic cups so it can stand upright. I grabbed each test tube and poured 2 ml of catalase solution into it. I also tapped and swirled to measure the bubbles by using the ruler. I wrote the numbers into the lab report. In the second experiment, I labeled the room
The Structure and Function of Carbohydrates Large biological molecules are called macromolecules, there are giant molecules (polymers) made up of repeating units (monomers). Carbohydrates are one of the main classes of biological molecules. Macromolecule units (monomers) are joined together by condensation reactions and hydrolysis reactions split macromolecules down into their individual units. Carbohydrates are molecules that contain elements of carbon, hydrogen, and oxygen. Carbohydrates have a 2:1 hydrogen to oxygen ratio, there are twice as many hydrogen atoms as oxygen atoms (the same proportion as in water).
We then cut our potato tubes with the cork borer and cut them with the scalpel so they were the same length and weighed them. We then put one potato tube in each test tube and then added the same amount sugar solution in to each tube. The concentration of sugar solutions varied in each test tube.
Beans and Legumes - black beans, chick peas, lentils, lima beans, peanuts, kidney beans, and soybeans
But now we have the rest of the result isn't bad to understand why the other tubes end up with that color and what happened with their starch inside. Starch + Boiled Amylase, Once the amylase reach certain temperature it will cause it proteins in enzyme to denature which cause changing in shape and not having the ability to work properly. So adding starch and Boiled Amylase will also cause the starch to not be broken down properly which cause a brown color looking at final, than Starch + Amylase + HCl: Due to presence of HCl, it will unfold the amylase, which it disrupt the shape of its active site, in consequence the enzyme is not functional anymore, so adding HCl to amylase will interrupt the amylase in order of breaking down starch, which caused it a yellow green after boiling, and last but not least is Starch + DI H2O: Since adding H2O to starch won’t cause a change in starch so we expect Lugol’s iodine solution to turn purple/black indicating unhydrolyzed starch and it turned out to be blue at the end
3 drops of Lugol’s iodine solution were added to tube 3 and 5 respectively and immediately recorded the result. 10 drops of Benedict’s reagent was added to tube 4 and 6 swirled very well to mix the contents were placed in a water bath boiling for 3 minutes. They were then removed after the time set and proper records were taken.
Tissue Iodine test for starch Benedict's test for reducing sugars Test for non-reducing sugars Potato Turned black/blue Turned green Turned yellow/pale orange Swede Grey/black Turned orange Turned dark orange Analysis: The aim of the experiment was to find out the water potential of swede and potato tissues. Firstly 12 potato strips and 12 swede strips were cut to 7cm long, 0.5cm width and 0.5 cm depth. The strips were weighed (start mass in results tables). Two potato strips were put in each petri dish which each contained a different sucrose solution (0.0, 0.2, 0.4, 0.6, 0.8, 1.0 mol dm-3).
The Benedict's Test is used to test the presence of simple sugars in a sample. If sugars are present, a color change will occur from blue to red. However, although the Benedict's test shows the presence of sugars, it cannot accurately determine the concentration of sugar in a sample solution. In our method, we added specific concentrations of glucose to the Benedict's test to use as a chart to estimate the glucose concentration of an unknown solution X. Although this gives a rough estimate of the concentration, it is very inaccurate. For example, the mystery solution X was a pale orange color, which was between the colors in my first and second test tube.
...eicosapentaenoic acid), and ALA (alpha-linolenic acid) are considered to be the three main fatty acids.
== § Test tubes X 11 § 0.10 molar dm -3 Copper (II) Sulphate solution § distilled water § egg albumen from 3 eggs. § Syringe X 12 § colorimeter § tripod § 100ml beaker § Bunsen burner § test tube holder § safety glasses § gloves § test tube pen § test tube method = == = =
immediately started to work. With a pipette, add 3 drops of the starch and amylase. solution is added to each dimple every thirty seconds. When the solution has turned back to the original colour of the iodine solution.
These natural sugars are carbohydrates called glucose and fructose. According to the article A Glossary of Natural Sugars & Added Sugars Glucose, glucose is a “‘simple’ sugar naturally found in all foods that have carbohydrate. Starch (e.g., in potatoes, pasta) is many glucose molecules linked together. Another simple sugar, fructose is often called “fruit sugar” because it’s the main type of natural sugar in fruits (and honey).” These sugars are found in sugar beets and sugarcane as well, but after the long refinement process, they become stripped of the proteins, vitamins and minerals that help your body break them down. The refined sugar, or table sugar as its commonly known, is referred to as sucrose. Sucrose is made up of both glucose and fructose. When consumed, your body will use the glucose as energy first, and any energy left over from the fructose will then be stored as fat