Determining protein concentration is crucial in research. Different methods like Biuret, Lowry, and Bradford are commonly used. These methods involve reactions with proteins to produce colored products, measured at specific wavelengths. In this study, protein concentrations from HeLa cells were compared using these methods. The modified Bradford method with CBB R-250 showed the highest protein concentration, while the commercial Bradford reagent gave the lowest. The study also includes teaching methods for high school students on amino acids and proteins, with practical experiments for group work.