Staining of nucleic acid by acetocarmine stain is based on the principle that acetocarmine stain combines with nucleic acid present in the nuclei of cells to form a deep red conjugate.

Nuclei in cells are rich in nucleic acid present in a conjugated form with the protein and forms nucleoproteinous structures called as chromatin fibres or chromosomes.

Acetocarmine dye is formed by a mixture of carmine and glacial acetic acid. It is a DNA-specific stain and hence is used to observe the chromosomes in different stages of mitosis.

In this biology class 12 practical, we’re going to learn about the staining procedure of nucleic acid within the chromosomes.

This simulation uses an epidermal peel of fleshy onion leaf as biological material. The epidermis is peeled off from the fleshy onion leaf and kept on the slide. Drop of water is added to avoid the desiccation of the plant material. Cut the small portion of the peeled epidermis and discard the remaining portion.

The excess water is removed with the filter paper. Acetocarmine drops are added on the epidermal peel. A cover slip is placed on the slide after gently heating on the spirit lamp. Onion epidermal peel is then observed under lower magnification of the microscope.

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Requirements for this Science Experiment

⦁ Magnifying lens ⦁ Small sharp scissors ⦁ Brush ⦁ Rubber bands ⦁ Paper bags ⦁ Paper clips and tags