how many membranes do gram negative bacteria have
Gram-negative bacteria Bacteria are traditionally divided into the two groups: gram-positive and gram-negative, based on their gram-staining response. Gram-positive bacteria are also referred to as monoderms having one membrane, and gram-negative bacteria are also referred to as diderms, having two membranes. These groups are often thought of as lineages, with gram-negative bacteria more closely related to one another than to gram-positive bacteria. While this is often true, the classification system breaks down in some cases. A given bacteria's staining result, bacterial membrane organization, and lineage groupings do not always match up.[6][7][8][9] Thus, gram-staining cannot be reliably used to assess familial relationships of bacteria. However, staining often gives reliable information about the composition of the cell membrane, distinguishing between the presence or absence of an outer lipid membrane.[6][10]