<P> 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 . Thus , gram - staining can not 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 . </P>
<P> 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 . Thus , gram - staining can not 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 . </P>
how many membranes do gram negative bacteria have
how many membranes do gram negative bacteria have
two
two