Biological Tools and Techniques

Different types of tools and techniques are used in biology, which help to simplify certain studies. These tools, like different types of microscopes, make the study easier. Also, various biological techniques help to break down and simplify certain complex phenomena, which may be almost impossible to understand.

Stereo microscopes can be used to magnify small objects to 20 - 40 times the normal size. The surface of specimen reflects the light from an external source, and when viewed through the two eyepieces, gives a “stereo” or three dimensional image.

Compound or bright field microscopes will typically magnify specimens to 400 times, while more sophisticated ones can magnify upto 2000 times. The magnification levels are possible as light is transmitted through very thin, color-stained specimens from below.

Phase contrast microscopes exploit different refractive indices of structures within a microscopic organism to give more detail. This is possible as light transmitted through different structures will come at the objective lens at different times, to provide contrast.

Fluorescent microscopes bombard specimens stained with fluorescent dyes with a high intensity light source of a specific wavelength. The transmitted light is then viewed through filters designed to limit light transmission to the lower energy, fluorescent light.

Confocal scanning microscopes are designed to visualize the internal fine structure of living cells in three dimensions. Structures within a cell are stained with fluorescent tags and a focused beam of ultraviolet light scans a section of a cell at a specified depth.

The images generated are captured and assembled into a 3D video of cellular activities.

Electron microscopes can magnify an object up to 250,000 times its original size, by bombarding a lead (Pb)-treated specimen with a beam of electrons. The electrons are deflected to different degrees by the atomic composition of various structures, while electrons able to pass through the specimen strike a crystal-coated screen to generate an image.

Scanning electron microscopes have the capacity to magnify the surface of objects up to 50,000 times, by scanning the metal-treated surface with a narrowly focused beam of electrons.

Reflected or metal-emitted electrons are captured by a detector, which in turn controls an electron beam to create an image on a screen.

Homogenization is the process of fracturing cells, for the purpose of isolating subcellular components. This can be accomplished by exposing cells to hypotonic buffers, sonication, detergents, or mechanical disruption.

Centrifugation enables isolation of homogenate components by size and shape, or density. A cellular homogenate spinning at high speed in a centrifuge will cause larger, more dense components to migrate toward the outside of the spin, where the amount of force is greatest. Smaller, less dense components will be displaced toward the center of the spin.

Colorimetry is the process of determining the concentration of a component within a solution by measuring the wavelength and amount of light able to pass through the solution.

Paper chromatography is performed by spotting a small amount of sample near the edge of a sheet of paper impregnated with solvent.

The same edge is then exposed to a different solvent, which causes sample components to migrate due to capillary action, but with different speeds due to the solubility properties of the different components. Visualization of the components is accomplished with dyes.

Thin-layer chromatography utilizes a glass or plastic plate coated with a thin layer of absorbent, allowing stronger solvents and dyes to be used. One end of the plate is spotted with sample and placed in a solvent.

Sample components move up the plate due to capillary action at different speeds due to solubility properties and interaction with the absorbent.

Ion-exchange chromatography utilizes a column filled with positively or negatively charge beads, which can separate proteins based on their net charge. Proteins bound to the beads can then be eluted using a salt solution that competes with the charged proteins.