Final answer:
Heat fixing makes cells adhere to a microscope slide by heating, which kills the microorganisms and makes their proteins coagulate.
Step-by-step explanation:
Heat fixing is a technique used in microbiology to make cells adhere to a microscope slide. In this process, a thin layer (smear) of the specimen is spread on a slide. The slide is then exposed to heat, often by passing it over a Bunsen burner flame.
The heat kills the microorganisms, causing the cellular proteins to coagulate and making the cells more adhesive to the glass slide. This approach not only secures the specimen in place for observation but also preserves the integrity of the cellular components and halts biological activity that might obscure microscopic details.
Moreover, heat fixing is a prerequisite for staining procedures. It prepares the smear for the application of various dyes, allowing microscopic observation of cellular structures with adequate contrast. Different dyes, such as cationic dyes like methylene blue or anionic dyes like eosin, interact distinctly with treated cells.