2-Bacterial Classification Flashcards
What is serotyping?
can distinguish a particular strain of bacteria with the use of Ab’s which detect characteristic antigens on the bacteria.
When is serotyping used?
Typically used to identify organisms that are either to dangerous or to difficult to grow in the lab, associated with specific disease syndromes, or need to be identified rapidly.
What is biotyping?
Biochemical testing, certain tests go with certain organisms. Connect what tests go with what organism. Catalase, coagulase, indole, etc.
What is DNA hybridization?
When DNA is heated to denaturation temperatures to form single strands and then cooled double helices will re-form (renaturation) at regions of sequence complementarity. This technique is useful for determining sequence similarity among DNAs of different origin and the amount of sequence repetition within one DNA.
When is DNA hybridization used?
Most commonly used for the analysis of sequences of ribosomal DNA to detect the highly conserved sequences of ribosomal DNA (identify a family or genus) and highly variable sequences (identify a family or genus)
What is the gram staining process?
Process: Bacteria Heat Fixed –> Stained with Crystal Violet –> Stained with Iodine –> Unbound and excess stain with washed away with Decolorizer (acetone based) and Water –> Stain with Safranin (Red Counterstain; added to stain any decolorized cells)
What bacterial cannot be classified by gram staining?
• Mycobacteria and mycoplasms cannot be classified by gram stain
What is the coccus shape?
a spherical-shaped bacterium. Many species of bacteria have characteristic arrangements that are useful in identification. Pairs of cocci are called diplococci; rows or chains of such cells are called streptococci; grapelike clusters of cells, staphylococci; packets of eight or more cells, sarcinae; and groups of four cells in a square arrangement, tetrads. These characteristic groupings occur as a result of variations in the reproduction process in bacteria
What is an example of a coccus bacteria?
staphylococcus aureus
What is the bacillus shape?
cylindrical or rodlike bacteria
What is an example of a bacillus bacteria?
B. anthracis
What is the spirillum shape?
Curved shaped bacteria
What is an example of a spirillum bacteria?
spirillum minus
What is the branched filamentous shape?
look like little filaments; often appear beaded when staining
What is an example of the branched filamentous shape?
candidatus savagella
What is the diplococcus shape?
paired spherical bacteria, including those of the genus Diplococcus, some of which are pathogenic
What is an example of a diplococcus bacteria?
neisseria meningitidis
What is the pleomorphic shape?
Different morphological forms of same species or strain. Changes within natural environment
What is an example of a pleomorphic bacteria?
diphtheroids, Corynebacterium sp
What is the cell wall of the gram + bacteria look like?
thick, multilayered cell wall consisting mainly of peptidoglycan surrounding the cell membrane. There is not outer membrane and therefore no hydrophobic barrier.
What are the 2 layers of the gram (-) bacteria?
1) Thin Peptidoglycan layer- makes up 5-10% of the cell wall by weight, no teichoic or lipoteichoic acids. 2) Outer membrane has lipopolysaccharides, access through this outer membrane is through porins. It maintains the bacterial structure and is a permeability barrier to large molecules and hydrophobic molecules. It also provides protection.
What is teichoic acid?
water-soluble polymers, containing a ribitol or glycerol residue linked by phosphodiester bonds; found in cell walls and is chemically bonded to peptidoglycan. Essential to cell viability and important factor in virulence.
What is lipoteichoic acid?
found in cell membrane and is chemically bonded to membrane glycolipid (fatty acid), particularly in mesosome. Anchored into the cytoplasmic membrane, these surface antigens are used to distinguish bacterial serotypes and promote attachment to other bacteria and to specific receptors on mammalian cell surfaces (adherence). When these antigens are shed initiate innate protective responses similar to endotoxin.
Where is teichoic and lipoteichoic acid found?
Gram + bacteria