Explain the differences between basic and acidic dyes and how they are used

What will be an ideal response?


Basic dyes are mildly basic on the pH scale. Being basic means they are positively charged, resulting in the stain being attracted to the negatively charged cell surface of microbes and easily entering cells. Frequently used basic dyes include methylene blue, crystal violet, safranin, and malachite green. Occasionally acidic dyes, such as nigrosin or India ink, are also used. Acidic dyes are negatively charged, so they do not easily enter cells. They stain the background of a specimen in a technique called negative staining. An advantage of negative staining is that it doesn't require heating or chemical fixation, and the dye is not absorbed by the sample. This means the sample has a more true-to-life appearance, with fewer distortions of delicate cellular features.

Biology & Microbiology

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Which of the following types of organisms are based on cellular life?

A. bacteria B. yeast C. plants D. animals E. All living organisms are based on cells.

Biology & Microbiology

At equilibrium the allele and genotype frequencies of a population change over time

Indicate whether the statement is true or false

Biology & Microbiology

The warm-blooded reptilian ancestors to the dinosaurs and mammals were the ________.

Fill in the blank(s) with the appropriate word(s).

Biology & Microbiology

DNA microarrays reveal

A) if any genes are mutated in a given cell. B) if reverse transcriptase is present in a given cell. C) which genes are being expressed in a given cell. D) which genes are found in a given cell. E) if a particular gene was acquired via horizontal gene transfer.

Biology & Microbiology