![]() GRAM (+) organisms hold onto the crystal violet-iodine complexmore tightly than the GRAM (-) bacteria do. Heat fix and perform the gram stain on this sample.ģ.) Observe all of your specimens under oil immersion and record cell morphology and arrangement and gram reaction. Mix the sample with a loopful of water on a microscope slide and allow the specimen to air dry. ) Use a sterile applicator stick to obtain a sample of the "crud" on your teeth at the gum line. 1.)Perform the gram stain on smears made form the following organisms:Ģ.Flood the smear with SAFRANIN, 1 minute, then wash with water. Flood the smear with ETHANOL-ACETONE, quickly, then wash with water. ![]() Flood the smear with IODINE, 1 minute, then wash with water. Flood the smear with CRYSTAL VIOLET, 1 minute, then wash with water. It divides most of the EUBACTERIA into two largegroups: GRAM POSITIVE bacteria and GRAM NEGATIVE bacteria. It requires a PRIMARY STAIN and aCOUNTERSTAIN. Also look up all of these stains in your Leboffe and Pierce book.) al., Chapter 3 and about gram positive and negative cells and their cell walls in Chapter 4, especially Table 4.1. (Read about staining techniques in Tortora et. We recognize those molecular shapes as foreign or different from our body's molecular shapes because they fit specific antigen receptors on our B-lymphocytes and T-lymphocytes, the cells that carry out adaptive immunity.Gram Stain, Capsule Stain and Endospore Stain An antigen is defined as a molecular shape that reacts with antibody molecules and with antigen receptors on lymphocytes. Proteins and polysaccharides associated with the acid-fast cell wall function as antigens and initiate adaptive immunity. The cytokines then bind to cytokine receptors on target cells and initiate inflammation and activate both the complement pathways and the coagulation pathway. The binding of these cell wall components to their corresponding pattern recognition receptors triggers the macrophages to release various defense regulatory chemicals called cytokines, including IL-1 and TNF-alpha. Most of the body defense elements are located in the blood, and inflammation is the means by which body defense cells and body defense chemicals leave the blood and enter the tissue around an injured or infected site.īody defense cells called macrophages, and dendritic cells have pattern recognition receptors such as toll-like receptors on their surface that are specific for the peptidoglycan fragments and mycolic acids in the acid-fast cell wall and/or to NODs in their cytoplasm that are specific for peptidoglycan fragments. Basically, the inflammatory response is an attempt by the body to restore and maintain homeostasis after injury. Inflammation is the first response to infection and injury and is critical to body defense. These cytokines can, in turn promote innate immune defenses such as inflammation, phagocytosis, activation of the complement pathways, and activation of the coagulation pathway. These PAMPS bind to pattern-recognition receptors or PRRs on a variety of defense cells of the body causing them to synthesize and secrete a variety of proteins called cytokines. (Because all microbes, not just pathogenic microbes, possess PAMPs, pathogen-associated molecular patterns are sometime referred to as microbe-associated molecular patterns or MAMPs.) Pathogenic Mycobacterium species such as Mycobacterium tuberculosis and Mycobacterium leprae release mycolic acid, arabinogalactan, and peptidoglycan fragments from their acid-fast cell wall. These unique molecules are called pathogen-associated molecular patterns or PAMPs. The body does this by recognizing molecules unique to microorganisms that are not associated with human cells. ![]() To protect against infection, one of the things the body must initially do is detect the presence of microorganisms. Layer 15 The periplasm contains enzymes for nutrient breakdown. ![]() Layer 4:The surface proteins in the acid-fast cell wall, depending on the strain and species, carry out a variety of activities, including functioning as enzymes and serving as adhesins, which enable the bacterium to adhere intimately to host cells and other surfaces in order to colonize and resist flushing.This is thought to contribute significantly to the lower permeability of acid-fast bacteria. There are far fewer porins in the acid-fast cell wall compared to the gram-negative cell wall and the pores are much longer. ![]()
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