What distinguishes the lipids of an archaeal plasma membrane from a bacterial one?

1. A bacterial membrane is a bilayer of phospholipids whose fatty acids are linked to glycerol. 2. In archaeal membranes, isoprene or phytanyl chains linked to glycerol take the place of those fatty acids. 3. Those phytanyl sidechains are branched rather than linear. 4. An ether bond rather than an ester bond joins the archaeal lipid to its glycerol. 5. Some archaeal membranes are lipid monolayers instead of bilayers, so lipids are certainly present. 6. Peptidoglycan is a wall material and never builds a membrane, which rules out the third option. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 22 "Prokaryotes: Bacteria and Archaea", section 22.2 Structure of Prokaryotes_