Macromolecules Lab
You will do a lab experimenting with macromolecules. You will be testing for lipids, carbohydrates and proteins.
Download this lab writeup.
Different foods change color when indicators were added to denote the presence of macromolecules. Why does this happen? To understand this phenomenon, you need to be able to describe the structures of carbohydrates, lipids and proteins and explain why they behave in the way that they do when exposed to certain indicators.
Develop your own research question.
You will have four (4) hypotheses. The hypotheses need to be tailored into "if...then" statements that are derived from the information presented in the Introduction. For example, "If nucleic acids are present in a sample, then adding phenolphthalein will turn the sample pink." You will complete four tests, so you should have four hypotheses.
Write an "if...then" statement for the presence of starch, one for the presence of proteins, one for the presence of lipids, and another for the presence of glucose.
Background Knowledge. Take a look at this interactive link. It describes the six functional groups. What is important for you to understand is what happens during the complementary processes of hydrolysis and dehydration. Another important fact is to understand what happens when electrons are donated by one molecule and received by another. Molecules that donate electrons are called reducing agents and molecules that receive electrons are reduced.
This lab has two parts: known samples and unknown samples.
We will be working with three specific reagents: Benedict's reagent, Biuret's reagent, and iodine solution. To test for lipids, we will put the samples in water.
Benedict’s reagent changes color when exposed to a reducing agent, and all monosaccharides are reducing agents. Some disaccharides (like sucrose) have no free carbonyl groups and thus are non-reducing agents.
Biuret's reagent changes color in the presence of proteins because the copper II ions form a complex with the nitrogen atoms. The color change ranges from blue to violet, and the more peptide bonds present, the more violet the change.
Iodine solution is good for identifying the presence of starch because iodine atoms can fit inside the helical structure of starch compounds and change the color from dark blue to black.
We will test for lipids by placing the sample into water. If the sample floats on top of the water, lipids are present.
If you want to know more (including the overwhelming biochemistry of it all, go here and here.
Download this lab writeup.
Different foods change color when indicators were added to denote the presence of macromolecules. Why does this happen? To understand this phenomenon, you need to be able to describe the structures of carbohydrates, lipids and proteins and explain why they behave in the way that they do when exposed to certain indicators.
Develop your own research question.
You will have four (4) hypotheses. The hypotheses need to be tailored into "if...then" statements that are derived from the information presented in the Introduction. For example, "If nucleic acids are present in a sample, then adding phenolphthalein will turn the sample pink." You will complete four tests, so you should have four hypotheses.
Write an "if...then" statement for the presence of starch, one for the presence of proteins, one for the presence of lipids, and another for the presence of glucose.
Background Knowledge. Take a look at this interactive link. It describes the six functional groups. What is important for you to understand is what happens during the complementary processes of hydrolysis and dehydration. Another important fact is to understand what happens when electrons are donated by one molecule and received by another. Molecules that donate electrons are called reducing agents and molecules that receive electrons are reduced.
This lab has two parts: known samples and unknown samples.
We will be working with three specific reagents: Benedict's reagent, Biuret's reagent, and iodine solution. To test for lipids, we will put the samples in water.
Benedict’s reagent changes color when exposed to a reducing agent, and all monosaccharides are reducing agents. Some disaccharides (like sucrose) have no free carbonyl groups and thus are non-reducing agents.
Biuret's reagent changes color in the presence of proteins because the copper II ions form a complex with the nitrogen atoms. The color change ranges from blue to violet, and the more peptide bonds present, the more violet the change.
Iodine solution is good for identifying the presence of starch because iodine atoms can fit inside the helical structure of starch compounds and change the color from dark blue to black.
We will test for lipids by placing the sample into water. If the sample floats on top of the water, lipids are present.
If you want to know more (including the overwhelming biochemistry of it all, go here and here.
After you have tested known samples, you will test unknown samples. The unknown samples are MIX, MAX & MOX. You must determine what macromolecule is present in each of the samples and back it up with data. HINT: None of the unknown substances contain lipids or proteins.
You need to create a chart for data collection. Remember that you will have three hypotheses. After you have collected your data, you need to determine if your hypotheses were supported by the data. I strongly suggest you show me your conclusions before you submit your work.
You need to create a chart for data collection. Remember that you will have three hypotheses. After you have collected your data, you need to determine if your hypotheses were supported by the data. I strongly suggest you show me your conclusions before you submit your work.