Bacterial Structure Flashcards
Name the types of differential staining.
Gram stain, acid fast stain
What is a gram stain?
A differential stain based on chemical differences in cell wall structure, particularly on the thickness of peptidoglycan layer and presence of outer membrane.
What is the primary stain of the gram stain?
Crystal violet; Stains all bacteria purple.
What is Mordant?
It complexes with crystal violet to forma a large aggregate within heat fixed cells; Iodine in gram stains.
What is decolorizer?
Usually alcohol or alcohol-acetone; Removes stain complex from gram negative cells but not gram positive cells; Alcohol in gram stain
What does Counterstain do?
Stains decolorized cells pink; safranin in gram stain.
What is an acid fast stain?
A differential stain that binds strongly to bacteria that have waxy material in the cell walls; Used especially for Mycobacterium species. Acid-fast bacteria stain red; all others are blue
Name the major criteria for grouping bacteria?
Cell structure, Differential staining, Oxygen requirements, Endospore formation, and motility
What is in prokaryotic cells?
Cytoplasm, CM, Cell wall, outer membrane (Gram -), sometimes flagella, NO nucleus or organelles
Describe the prokaryotic cytosol.
Where most metabolic reactions take place, Ribosomes of 50s and 30s subunits; Coupled transcription and translation. A single circular chromosome with dsDNA; Super coiled by gyrase. May have plasmids that replicate independently of the chromosome.
Describe the Prokaryotic CM
Responsible for respiration; Contains a phospholipid bilayer but doesn’t contain sterols. The location of ETC and ATP synthase. Makes cell walls and secrets enzymes and toxins. Also contains chemotactic receptors.
Describe the Prokaryotic capsule
Hydrophillic layer around cell; Outside the outermost layer of cell wall. Not unique to either Gram positive or Gram negative. Usually a sugar and antigenic. An important virulence factor; Anti-phagocytic, Adhesin and invasin.
Describe the Prokaryotic cell wall
Rigid, gives shape to cell. PREVENTS OSMOTIC RUPTURE of the cell. Reacts with gram stain. Contains peptidoglycan; Unique to prokaryotes.
What is peptidoglycan?
A polymer only found in prokaryotes; Anti-phagocytic, Mitogenic, and pyrogenic. It is a linear chain of two alternating sugars with peptide crosslinks making one covalent molecule; Sugars are N-acetylglucosamine and N-acetylmuramic acid. Muramic acid is only found in peptidoglycan.
Describe peptiodglycan
Attached to each muramic acid residue is a peptide chain; Contains D-amino acids and diaminopimelic acid.