What are the 4 major steps in gram staining and what is the role of each reagent

Gram was a Danish doctor and bacteriologist best known for inventing the Gram staining technique in microbiology. Gram staining is a technique used to identify bacteria into two different groups, Gram-positive and Gram-negative. First, a sample of bacteria affixed to a microscope slide and treated with crystal-violet stain, a common dye in histology.

This turns all of the bacterial cells a bright purple color. The slide is then washed with iodine to fix the purple color. Then the slide is washed again with an organic solvent such as acetone or alcohol.

Preparation of gram staining reagents

Some cells will remain stained purple. The bacterial cells that stay purple are called Gram-positive. The cells of Gram-positive bacteria contain a compound called peptidoglycan that absorbs the stain and thick cell walls to resist the penetration of the solvent. The cells that did not retain the purple coloring are Gram-negative.

Their cells walls are thinner than Gram positive and the solvent can wash away any of the purple stain.

Discussion for gram staining lab report

Gram found he could treat the sample again with a counterstain of fuchsine or safranin. This would turn the Gram negative cells a bright pink making them easier to distinguish from Gram positive under a microscope. Gram staining is a good first test when attempting to identify a strain of bacteria. When combined with shape identification, growth media, and aerobic or anaerobic is often enough to identify a particular bacteria.

Miramontes was a Mexican chemist who first synthesized the compound norethindrone. Norethindrone would be the basis for progestin, the first oral contraceptive.