Differences between Gram positive and Gram negative bacteria include the thickness of the cell wall, which is approximately 20 to 30 nanometers thick in Gram positive and 8 to 12 nanometers thick in Gram negative; the am... More » Science Biology

Examples of Gram-negative bacteria species include Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Vibrio cholerae and Neisseria gonorrhoeae. Escherichia coli is a Gram-negative bacterium that causes foo... More » Science Biology

In microbiology, gram staining is an important test used because it can determine the presence of bacteria in a sample, as well as differentiate between the two distinct bacteria species, which are gram-positive and gram... More » Science Biology Cells
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Gram staining targets the cell wall and a layer called peptidoglycan. Since human cells do not have cell walls or peptidoglycan, the gram stain would do nothing because the primary stain would wash out, notes Wikipedia. More » Science Biology Cells

Items covered in a dichotomous key include whether bacteria are Gram positive or negative, catalase positive or negative, have nitrate enzymes, and contain the enzyme coagulase. The key is a set of questions that when co... More » Science Biology

Gram-negative bacilli are rod-shaped bacteria that have a thin layer of peptidoglycan between two membranes. They are medically significant as many strains can cause infection in humans, including the family Enterobacter... More » Science Biology

A Gram stain showing gram-positive cocci in pairs, or diplococci, is a morphological characteristic of several bacteria. Gram stains can be positive or negative, depending on the cell wall composition of the bacteria. Mo... More » Science Biology