Micro biology chapter 9 study Essay

Nicole Anderson
Wed. Microbiology
7/15/14
Chapter 3
Learning Objectives
1. Glycocalyx is a gelatinous, sticky substance that surrounds the outside of a cell. It may be composed of polysaccharides, polypeptides, or both. They form capsules or loose slime layers that protect cells from desiccation (drying). With regard to human health, the presence of a glycocalyx is a feature of numerous pathogenic bacteria and these glycocalyces play an important role in the ability of these cells both to survive and to cause disease.
2. The slime layer is loose and water-soluble. It is often sticky or viscous and provide a way for bacteria to attach to surfaces. The capsules are composed of organized repeating units of organic chemicals firmly attached to the cell surface. These chemicals in capsules are similar to those normally found in the body, the may prevent bacteria from being recognized or devoured by defensive cells of the host.
3. Bacterial flagella are responsible for a cells’ motility, enabling the cell to flee from a harmful environment or move toward a favorable environment such as one where food or light is available.
4. Four bacterial flagellar arrangements are:
Monotrichous- having a single flagellum at one end of a bacterial cell
Peritrichous- flagella cover the surface of the bacterial cell
Lophotrichous- two or more flagella at one end of a bacterial cell
Amphitrichous- a single flagella is at both ends of a bacterial cell (polar)
5. Fimbriae are sticky, bristlelike projections to adhere to one another and to substances in the environment. There may be hundreds per cell. They are usually shorter that flagella and are used to move bacteria across a substrate or toward another bacterium. Pilli are a specialized type of fimbriae that is longer that other fimbriae and usually shorter that flagella. Typically only one to a few are present per cell in bacteria that have them and they mediate the transfer of DNA from one cell to the other through conjugation.
6. Common shapes and arrangements of bacterial cells are spherical cocci and may be in arrangements such as single, chains (streptococci), clusters (staphylococci) and cuboidal packets, they can also be rod-shaped bacilli that ay be single or in arrangements such as chains.

7. Gram-positive bacterial cell walls have a relatively thick layer of peptidoglycan that also contains unique chemicals called teichoic acids. Some of these acids are covalently linked to lipids, forming lipoteichoic acids that anchor peptidoglycan to the cytoplasmic membrane. Gram-negative bacterial cell walls have only a thin layer of peptidoglycan, but outside this layer is an asymmetric bilayer membrane. The inner leaflet of the outer membrane is composed of phospholipids and proteins, and the outer leaflet is mad of lipopolysaccharide (LPS). Because the cell walls of Gram-positive and Gram-negative differ, the Gram stain is an important diagnostic tool. Gram-negative cells appear pink, and Gran-positive cells appear purple.
8. Because killing large numbers of Gram-negative bacteria with antimicrobial drugs releases large amounts of lipid A, which might threaten the patient more than the live bacteria, any internal infection by Gram-negative bacteria is cause for concern. The outer membrane may also be an impediment to the treatment of disease by preventing the movement of penicillin to the underlying peptidoglycan, rendering the drug ineffectual against many Gram-negative pathogens.
9. Endospores are formed by a process called sporulation, which requires 8-10 hours and proceeds in seven steps. Depending on the species, a cell forms an endospore either centrally, subterminally (near one end), or terminally (at one end). Endospores function to constitute a defensive strategy against hostile or unfavorable conditions and are important because of their durability and potential pathogenicity.
10. Eukaryotic cell walls have sticky carbohydrate glycocalyces that are anchored to

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