Pet-The-Bunny

A more common pronunciation of "peptidoglycan". Peptidoglycan, also known as murein, is a polymer that forms a homogeneous layer lying outside the plasma membrane and is only found in eubacteria (note: archaea have pseudopeptidoglycan). It serves a structural role in the cell walls of bacteria, giving them shape and strength and counteracting the osmotic pressure of the cytoplasm. It is also involved in the binary fission (reproduction) of the bacterial cell. Peptidoglycan is a target for many antibacterial drugs, such as penicillin, which works by interfering with the formation of the peptidoglycan layer, specifically the crosslinking enzyme transpeptidase. The peptidoglycan layer is thicker in Gram-positive bacteria (20 to 80 nm) than in Gram-negative bacteria (7 to 8 nm), with the attachment of the S-layer. It forms around 90% of the dry weight of Gram-positive bacteria but only 10% of that of Gram-negative bacteria. The peptidoglycan layer in the bacterial cell wall is a crystal lattice structure formed from linear chains of two alternating amino sugars, namely N-acetyl glucosamine (GlcNAc) and N-acetyl muramic acid (MurNAc). Each MurNAc is attached to a short (4 to 5 residues) amino acid chain. Cross-links between amino acids in different linear amino sugar chains by an enzyme known as transpeptidase result in a 3-dimensional layer that is strong and rigid. The specific amino acid sequence and molecular structure vary with the bacterial species. Pet-The-Bunny was originally created by a pair of genius biology students while they were expressing themselves in a PowerPoint presentation. note: there was originally a third student, but he was unwilling to participate and therefore caused a drop in the team's score.