cell wall of bryophyta is made up of chloroplasts.
cell wall of bryophyta is made up of?
chloroplasts
around the outside of the cell membrane is the bacterial cell wall. bacterial cell walls are made of peptidoglycan (also called murein), which is made from polysaccharide chains cross-linked by unusual peptides containing d-amino acids. bacterial cell walls are different from the cell walls of plants and fungi which are made of cellulose and chitin, respectively. the cell wall of bacteria is also distinct from that of archaea, which do not contain peptidoglycan. the cell wall is essential to the survival of many bacteria, although l-form bacteria can be produced in the laboratory that lack a cell wall. the antibiotic penicillin is able to kill bacteria by preventing the cross-linking of peptidoglycan and this causes the cell wall to weaken and lyse. the lysozyme enzyme can also damage bacterial cell walls.
cell wall
penicillin, its derivatives and methicilin, are beta-lactams that all work by disrupting the mechanical structure of the bacterial cell wall by reacting with the cell wall forming penicillin-binding protein family (pbp 1,2, 3 and 4), causing the cytoplasm to leak and the cell to die. however, the meca gene codes for pbp2a, that has a lower affinity for antibiotic drugs, which keeps the structural integrity of the cell wall, preventing cell death. the synthesis of the bacterial cell wall in "s. aureus" is dependent on transglycosylation, to form linear polymer of sugar monomers, and transpeptidation, to form an interlinking peptides to strengthen the newly developed cell wall. pbps have a transpeptidase domain, but transglycosylation was thought to only be carried out by monofunctional enzymes, however pbp2 has domains to carry out both essential processes. when antibiotics are introduced to the medium, they bind to the transpeptidation domain and inhibit the ability of pbps to cross-link muropeptides, therefore preventing the formation of stable cell wall. however, with cooperative action, pbp2a lacks the proper receptor for the antibiotics and continues the transpeptidation, preventing the breakdown of the cell wall. the functionality of pbp2a is dependent on two structural factors on the cell wall of "s. aureus." first, there in order for pbp2a to properly fit onto the cell wall, to continue transpeptidation, requires proper amino acid residues, specifically a pentaglycine residue and an amidated glutamate residue. furthermore, pbp2a has an effective transpeptidase activity, but lacks a transglycosylation domain of pbp2, which builds the backbone of the cell wall with polysaccharide monomers, and so pbp2a must rely on pbp2 to continue this process. the latter of these factors is an enzymatic reaction that can be targeted to improve the ability of beta-lactams to prevent cell wall synthesis in resistant "s." aureus. identification of genetic inhibitors of glycosylases involved in the cell wall synthesis, and modulating the expression of these inhibitors can resensitize these previously resistant bacteria to beta-lactam treatment. for example, epicatechin gallate, a compound found in green tea, has shown signs of lowering the resistance to beta-lactams, to the point where oxacillin becomes effective to inhibit the formation of the cell wall, by inhibiting pbp2 and pbp2a.
meca (gene)