lectures 9 and 10 - Lecture 9 and 10 Vocab Tissue tropism-...

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Lecture 9 and 10 Vocab Tissue tropism - a term most often used in virology to define the cells and tissues of a host which support growth of a particular virus . Fimbriae and protein carbohydrate receptors interactions enable piliated bacteria to display tissue tropism and host selectivity. Chemotaxis - The directed movement to chemical gradients. Certain gradients cause an attraction to the cell while others repel the cell. Chemoreceptors control the cells recognition of the chemical gradients. Chemoreceptor - sensory proteins located in the bacterial cytoplasm membrane that regulate the flagella motor rotation. They bind to chemicals in the external environment sensing their presence and change in concentration. Phototaxis - Cells have photoreceptors that sense gradients of photosynthetically active light that interact with proteins that affect flagella rotation to control the duration of runs and frequency of tumbles. Aerotaxis - Same as phototaxis but the receptors sense the change in oxygen in the environment. Nucleoid - A distinct structure of aggregated DNA plus a few specialized proteins confined to a discrete internal region of the bacterial cell [no nuclear membrane or ribosomes within it]. Houses the bacterial chromosomes: closed, circular double stranded molecule of DNA. Supercoiling - Bacterial DNA is supercoiled and stabilized by special proteins. DNA strands are broken and rotated to form the super coil. Plasmid - Small circular genetic elements that replicate separately from the chromosome, each molecule has its own origin of replication. Major types of plasmids: R plasmid- confer antibiotic resistance. Col plasmids- contains genes for bacteriocins. Virulence plasmids- produce toxins, host defense resistance. Metabolic plasmids- genes for specialized pathways such as pesticide degradation. Bacteriocin
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This note was uploaded on 04/02/2008 for the course PSY 101 taught by Professor Jackson during the Fall '08 term at Michigan State University.

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lectures 9 and 10 - Lecture 9 and 10 Vocab Tissue tropism-...

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