CLINICAL MICROBIOLOGY ENTRANCE EXAM 2023 with Verified Solutions 100% Correct

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Bacteria *** Single-celled organism that do not have a cell nucleus and the membrane-enclosed intracellular structures found in most other cells (Prokaryotic cell). Gram-positive Bacteria *** Thick ... layer of peptidoglycan (20-80nm across). The peptidoglycan layer is closely attached to the outer surface of the cell membrane. Retains crystal violet stains. Lack an outer membrane and a periplasmic space. Gram-negative Bacteria *** Cell wall is thinner, but more complex. Only 10-20% peptidoglycan. Contains an outer membrane, leaving a very narrow periplasmic space. Does not retain crystal violet stain because of large quantities of lipoproteins and lipopolysaccharides (endotoxin). Acid-fast Bacteria *** Cell wall is thick, but consists of 60% lipids. Lipids make acid-fast organisms impermeable to most other stains and protect them from acids and alkalis. Stain as gram-positive. Grow slowly because the lipids impeded entry of nutrients. [Show More]

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