Biological Molecules Lab Report

INTRODUCTION
Proteins are large complex organic macromolecules which are utilized for many important roles in the body. Proteins function in structure, transport, energy conversions, and play an important role in defense against diseases. Protein is also important for muscle recovery, which is why it is commonly associated with fitness.

Though your body will always absorb 1g of protein the same way every time, protein companies like to make their product competitive by offering a variety of qualities and ingredients in their protein supplements. A brand of protein powder, “Tough Guy”, claims that if a person were to dilute 1 gram of protein powder in 100ml of water, the final concentration should be approximately 0.40 mg/ml (+/- 5%) protein. The objective of this experiment is to determine whether the manufacturer is telling the truth. MATERIALS AND METHODS

One gram of Tough Guy protein powder was added to 100 ml of water. 50 µl of the sample was added to respective test tubes: 0.2, 0.3, 0.6 and 0.9 mg/ml protein. 2.5 ml of diluted Bio-Rad assay solution was pipetted into each test tube. Each test tube was covered with Parafilm and placed over approximately 6-8 seconds. The solutions were placed at room temperature for one hour. Optical density was measured using a spectrophotometer at 595 nm. The relationship between the absorbance and concentration of the reaction was recorded on an Excel spreadsheet. RESULTS

The experiment of the controls 0.2, 0.3, 0.6 and 0.9 mg/ml protein yielded optical densities of .231, .329, .645 and .970, respectively. Figure 1 shows a positive correlation between absorbance and concentration; as the protein concentration increased, so did the absorbance.

Figure 1. Relationship between average absorbance and protein concentrations
of 0.2, 0.3, 0.6 and 0.9 mg/ml protein.

DISCUSSION
The experiment showed a positive correlation between increasing protein concentrations and absorbance. Our calculated value for the concentration of protein was .306 which was lower than the suggested manufacturer’s value of 0.4. Variables which could have affected our values include sanitation between our hands and the test tubes and human error. The trendline represents a positive linear correlation between concentration and absorbance. Our experiment was conclusive and proves that the Tough Guy protein supplement may not be as concentrated as the manufacturer suggests.