Macromolecule Testing Lab

Macromolecule Testing Lab Description

For our first unit of our tenth grade STEM Biology class, we studied macromolecules. To help us learn about macromolecules and their attributes, we did a macromolecule testing lab. In this lab we tested the three macromolecules, proteins, lipids and carbohydrates, that are found in foods, with an indicator solution or paper towel. Then we did these same tests with water to represent a negative result, and compared those tests with our macromolecule tests to see whether they were positive or not. Besides from the water control tests, we ran four tests in total. Two of these tests, the monosaccharides and polysaccharides, were carbohydrates, the third test was for proteins, and the last test was for lipids.

Macromolecules Details

Macromolecules are small building blocks that make up cells and organelles. There are four basic types of macromolecules, which are, lipids, proteins, carbohydrates, and nucleic acids. Each of these macromolecules, also known as polymers, are made up of even smaller building blocks, or subunits, named monomers. All of these polymers have specific functions that are vital to living organisms, and can also all be found in foods.

Lipids are polymers which are found in fatty foods, like for example, avocados, cheese, and eggs. The monomers that make up lipids are fatty acids and glycerol. Some important functions of lipids are to provide long term energy storage for the body, to provide insulation, and to make up the basic structure of the cell membrane. The types of lipids used for the cell membrane are phospholipids, which have a hydrophilic head and hydrophobic tails, that act as a semipermeable membrane. To test a food for whether it has lipids, you can make a solution out of the food and smear it on a paper towel or paper bag, the indicator. After waiting ten minutes, if the area of the solution is see through, then the food contains lipids.

Proteins are polymers made up of chains of the monomers amino acids, these chains are also known as polypeptides. Meat and fish contain a lot of protein, but some other examples are milk, eggs, and soy products. Important functions of proteins are, to build and repair muscles and tissues, and for some types of proteins, called enzymes, to speed up chemical reactions. A couple interesting facts about proteins are that there are twenty different kinds of amino acids, and that six of these amino acids cannot be made in our body and can only be found in food. The protein indicator test for a food, requires a Biuret's indicator solution. In a vile you add two milliliters of a food solution, and 0.75 milliliters of the Biuret's solution. After mixing the solutions together, you watch as the color changes after thirty seconds. A positive test will result in a purple color, while a negative test will stay blue.

Carbohydrates, or polysaccharides, are polymers that have a different function from their monomers, which are simple sugars, or monosaccharides. There are two main groups of types of carb food groups. Simple carbs, or monosaccharides, are found in candies, sugary drinks, fruits, and vegetables. While complex carbs, or polysaccharides, are more like starches found in pasta, bread, and potatoes. All carbs supply our with energy, but they can in two different ways. Monosaccharides like glucose supply a quick burst of energy, while polysaccharides like starch, provide more long term energy for the body. Interestingly enough, these different types of carbs can each be tested differently for foods. For simple sugars, you mix two milliliters of the food solution with two milliliters of Benedict's indicator solution in a vile. Then you heat it at 100 degrees Celsius for two minutes. A positive result is orange, green or brown, while a negative result is blue. For complex carbs, you mix two milliliters of the food solution with 0.1 milliliter of Iodine in a vile. Then you just gently swirl and record how it changes colors. a positive test result would be black or purple, and a negative test result would be orange, red, or brown

Nucleic acids are made up of the monomers nucleotides, and these nucleic acids are the DNA and RNA in our cells. The main components from nucleic acid can be found in minerals and vitamins. Therefore nucleic acids can be found in foods that contain these vitamins and minerals, like fruits, vegetables, meats, and grains. The primary and pretty much only function of nucleic acids are to store and carry genetic information. Nucleic acids are one of the two basic macromolecules which have more than the three main elements of hydrogen, carbon, and oxygen. For our macromolecule testing lab, we did not test any foods with a nucleic acid indicator test, however there is one. It is called the dische diphenylamine test, and comes out dark blue when positive and clear blue when negative.

Reflection

As we worked together on our macromolecule testing lab, our group got work done pretty efficiently. However we could have worked on our project even more effectively if we improved our skills as conscientious learners. For this lab we had to run four different indicator tests on foods and the also each another time on water. in total this lab included eight tests we had to setup and run in the time of two class periods. We eventually got all of these tests done but we could have been more productive if we had managed our time more effectively. If we had split up into two groups, we could have divided our work equally and finished the tests with more time to spare, and without rushing.

While working throughout this lab, our group communicated very well. Throughout the tests, we had to use precision with pipettes requiring a lot of communication between our teammates so we would not spill an indicator solution and stain our hands. Our group executed these tests very well and had great communication with each other. Thankfully due to our communication, no one from our group left class with iodine stained hands.