Laboratory Methods & Separations

The MCAT tests laboratory techniques heavily because they underpin the experimental passages in every science section. This lesson covers how scientists separate, quantify, and identify molecules: chromatography (partitioning by polarity, size, or charge), gel electrophoresis (separating nucleic acids and proteins by size and charge, including SDS-PAGE and isoelectric focusing), centrifugation (sedimentation by density and mass, including density-gradient methods), and spectroscopy (UV-Vis with the Beer–Lambert law $A = \varepsilon b c$, plus IR, NMR, and mass spec for structure). The interactive lesson works through each method, when to choose it, and how to read its output on a passage.