For first-year biochemistry students, learning laboratory techniques like chromatography, electrophoresis, and spectrophotometry is essential. These methods are fundamental for analysing molecules and understanding their properties. Let’s break down each technique in a way that’s easy to understand and provide specific tips to help you get a good grasp of them.
1. Chromatography: Separating Molecules Based on Their Properties
Chromatography is a method used to separate molecules in a mixture based on their physical or chemical properties. The two main types you’ll encounter are thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). The key concept here is the partition between a stationary phase (like a thin layer of silica) and a mobile phase (like a solvent). Different compounds will move at different speeds, separating them.
Tip for Understanding: Imagine chromatography like watching people walk on different terrains. Some might walk faster on a smooth path (mobile phase), while others might get stuck in mud (stationary phase). This visual analogy helps when you’re thinking about why molecules separate. In TLC, practice by spotting your sample carefully and observing how it moves with the solvent. If spots aren’t clear, review your technique or try another solvent to see if the separation improves.
2. Electrophoresis: Sorting Molecules by Size or Charge
Electrophoresis is often used to separate DNA, RNA, or proteins based on size or charge. In gel electrophoresis, molecules move through a gel matrix under an electric field. Smaller molecules move faster, and if charged, they will move toward the opposite pole. This technique is especially common in DNA analysis, where scientists use it to visualise DNA fragments.
Tip for Mastering Electrophoresis: Imagine trying to push objects of different sizes through a net — smaller items move through easily, while larger ones struggle. This idea of molecular “sieving” is exactly what happens in gel electrophoresis. When setting up your gel, ensure the wells are filled carefully, and avoid overloading them to prevent smearing. Start with clear and evenly-spaced bands. If your bands are smeared or faint, you might need to adjust the gel concentration or voltage settings.
3. Spectrophotometry: Measuring Light Absorption to Determine Concentrations
Spectrophotometry measures how much light a sample absorbs. When light passes through a sample, molecules absorb specific wavelengths, providing data about concentration. You’ll often use this technique to determine the concentration of solutions, especially in reactions involving coloured products.
Tip for Spectrophotometry: Think of a spectrophotometer like sunglasses that can detect specific colours absorbed by a solution. Each molecule has a “favourite” wavelength it absorbs best. Practice with samples of known concentrations to understand the relationship between absorbance and concentration (Beer-Lambert Law). Also, clean the cuvette thoroughly before every measurement to avoid cross-contamination and inaccurate readings.
Essential Skills: Experimental Design and Data Analysis
Every lab experiment requires careful planning (design) and data analysis. Experimental design means deciding how you’ll set up an experiment, including controls and variables. Start by identifying your hypothesis, then choose controls that will allow you to compare results objectively.
Tip for Better Data Analysis: After running your experiments, record your observations meticulously and make simple graphs to visualise your results. If you’re analysing enzyme kinetics or concentration data, understand the trend rather than just focusing on numbers. Look for “outliers” that don’t fit and consider possible reasons, such as procedural errors or unexpected reactions.
These lab techniques will come up repeatedly in biochemistry, so the more you practice, the easier they’ll become. With the right approach, you can make these methods not just understandable, but a powerful part of your scientific toolkit.