Microbiology Study Documents

What are the 3 domains? Bacteria, Archaea, Eukarya organelles found in all bacteria cells cell wall, 70S ribosomes, nucleoid and inclusion bodies organelles in some bacteria flagellum, pilli, capsule and endospore 3 main regions of bacterium cell envelope, cytoplasmic region and appendages Components of the cell envelope cell wall and cell membrane and capsule Prokaryotic cell wall contains peptidoglycan and surrounds all cells except mycoplasmas peptidoglycan linear chine of alternating units of NAM and NAG which are linked by 1-4 glycosidic bonds cross links in peptidoglycan L and D amino acids may form cross bridges with NAM gram negative components Only one layer of peptidoglycan plus contains periplasm and an outer membrane periplasmic gel Formed from minimal cross links in peptidoglycan provides shape and integrity outer membrane Contains LPS Negative charge helps against phagocytosis evasion LPS (lipopolysaccharide) Extremely toxic LPS components lipid A, core polysaccharide, O antigen Porins Special proteins channels made to allow movement of hydrophilic molecules due to LPS Gram positive thicker due 20 layers of peptidoglycan and teichoic acid teichoic acid covalently linked to NAM and anchors wall to cell also negatively charged 1/3 Stain of gram positive Purple as iodine crystals are kept inside peptidoglycan Stain of gram negative pink Capsule hydrophilic gel Nucleoid A dense region of DNA in a prokaryotic cell. 70s ribosomes smaller ribosomes found in prokaryotes made of 2 subunits 30S and 50s Antibiotic action against ribosomes Bind to the 30S region inhibiting RNA translation Inclusion granules Energy reserves Flagella A long, whip-like filament that helps in cell motility made of flagellin Monotrichous single flagellum Lophotrichous a tuft of flagella coming from one pole amphtrichous flagella at both ends of cell Peritrichous flagella all over Chemotaxis Cell movement that occurs in response to chemical stimulus phototaxis movement in response to light Aerotaxis response to oxygen pili made of pillin and acts as adhesion sex pili longer than fimbriae and allow prokaryotes to exchange DNA endospore A thick-walled protective spore that forms inside a bacterial cell and resists harsh conditions. 4 stages of peptidoglycan synthesis autolysis breaks glycosidic bonds in peptidoglycan chan and in cross bridges Monomers are synthesised in the cytosol and carried cytoplasmic membrane by 2/3 bactoprentos Transglycosidase inserts and links new peptidoglycan into the broken chain Transpeptidase reforms cross links Antibiotic activity on peptidoglycan synthesis Inhibits transpeptidase lag phase of bacterial growth The first phase of the bacterial growth curve, in which organisms acclimate to their surrounding; they grow in size but do not increase in number. Log phase of bacterial growth The second of the four phases of bacterial growth, in which cells divide at an exponential rate. stationary phase of bacterial growth the number of newly generated cells is the same as the number of dying cells death phase of bacterial growth as resources become insufficient, bacteria die off Equation of mean generation time T * log2 /logb - loga t=tb - ta tb= time in minuets at end of selected growth phase ta= time in minuets at start of selected growth phase logb= log of cells at end of selected growth phase loga= log of cells at start of selected growth phase antibiotic A substance made by microorganisms which at low concentrations kills other microorganisms 3/3