32Cell Wall Less FormsA few bacteria are able to live or exist without a cell wall.The mycoplasmas are a group of bacteria that lack a cell wall. E.g. Mycobacterium tuberculosis, M. Leprae etc.They have sterol-like molecules incorporated into their membranes and they are usually inhabitants of osmotically-protected environments.Sometimes, under the pressure of antibiotic therapy, pathogenic bacteria can revert to cell wall-less forms (called spheroplasts or protoplasts) and persist or survive in osmotically-protected tissues.When the antibiotic is withdrawn from therapy the organisms may regrow their cell walls and reinfect unprotected tissues.
37What We Learn………….True capsule is a discrete detectable layer of polysaccharides deposited outside the cell wall.A less discrete structure or matrix which embeds the cells is a called a slime layer or a biofilm.Capsules play an important role in attachment & prevention of bacteria from phagocytosis.Gram positive bacterial cell wall consists of several layers of peptidoglycan & teichoic acid is a special feature.Gram negative bacterial cell wall consists of a single layer of peptidoglycan & a unique component LPS is present.Mycoplasmas are cell wall lack forms.Proteins & lipids constitutes a Fluid Mosaic Model of bacterial cell membrane.
39Tips For Critical Thinking Questions Gram positive bacteria produce exotoxins which has high potency. It is an enzyme which interferes ADP-ribosylation.Cell membrane has special transport systems which can pass the large nutrients & ions through the membrane. These are facilitated diffusion, active transport & group translocation.