Chapter 1.1 Bacterial Taxonomy Flashcards
What color does a gram-positive organism stain?
Blue
What color does a gram-negative organism stain?
Red
What is the peptidoglycan layer?
Cell wall that is outside the bacterial cytoplasmic membrane
What organisms is the peptidoglycan layer present?
Gram-positive and gram-negative
What is the function of transpeptidase?
An enzyme that catalyzes the formation of the links of amino acids of peptidoglycan
What are the characteristics of the gram-positive cell wall?
Very thick and have extensive cross linking of amino acid side chains
What are the characteristics of a gram-negative cell wall?
Very thin with simple cross-linking pattern
What important polysaccharide is present in gram-positive cell walls?
Teichoic acid
*teichoic acid is not present in gram-negative cell walls
What lipoprotein is present in gram-negative cell walls?
Murein lipoprotein
What does the outermost portion of the bilayer contain in gram-negative organisms?
Lipopolysaccharide (LPS)
What are the components of LPS?
Outer carbohydrate of oligosaccharides, center part called core polysaccharide, and interior to the core is lipid component
What is lipid A?
The gram-negative endotoxin that is toxic to humans
What manifestations occur when lipid A is released into the circulation from lysis of bacterial gram-negative cells?
Fever, diarrhea, possible fatal endotoxin shock (septic shock)
What allows for passage of nutrients in only gram-negative cells?
Porin proteins
What is the importance of the structure of gram-positive cells vs gram-negative cells?
The thick peptidoglycan of a gram-positive cell does not block diffusion of low molecular weight compounds allowing substances that damage the cytoplasmic membrane to pass through (antibiotics, dyes, and detergents).
The gram-negative LPS blocks the passage of these substances.
Can antibiotics and chemicals attack gram-negative bacteria?
No, because the LPS is blocking access to the peptidoglycan later
Examples of chemicals that can attack the peptidoglycan layer?
Penicillin and lysosomes
What are the 4 major shapes of bacteria?
Cocci, bacilli, spiral forms, and pleomorphic
What is the shape of cocci bacteria?
Spherical
What is the shape of bacilli bacteria?
Rod shaped
What are short bacilli called?
Cocobacilli
What is the shape of spiral formed bacteria?
Comma-shaped, S-shaped, or spiral-shaped
What is the shape of pleomorphic bacteria?
Lack a distinct shape (like jello)
What are diplococci?
Pairs of different shapes that organize together into a more complex pattern
What are the shapes of the 6 classic gram-positive cells?
2 cocci and 4 bacilli
What are the 2 gram-positive cocci?
Streptococcus- form strips of cocci
Staphylococcus- form clusters of cocci
*both have cocci in the name
What are the 2 spore forming gram-positive bacilli?
Bacillus
Clostridium
What does spore mean?
Spheres that protect a dormant bacterium from the harsh environment
What 2 gram-positive bacilli do not form spores?
Corynebacterium
Listeria
What is unique about Listeria?
It’s the only gram-positive organism that has endotoxin
What is the only gram-negative cocci?
Neisseria which is a diplococcus
What is the 1 group of spiral-shaped organisms?
Spirochetes
What is the syphillis causing spirochete?
Treponema pallidum
What are the 2 shapes of all gram-negative organisms other than Spirochetes?
Rods or pleomorphic
What organisms are exceptions to bacterial morphology?
Mycobacteria, Spirochetes, and Mycoplasma
What is the morphology of mycobateria?
Weakly gram-positive but stain with a special acid-fast stain
Includes tuberculosis and leprosy organisms
What is the morphology of Spirochetes?
Gram-negative cell wall but are too small to be seen with a microscope so have to use darkfield microscope
What is the morphology of mycoplasma?
Do not have a cell wall
Only have a simple cell membrane
They are neither gram-positive or gram-negative
What are the 3 enzymes that some bacteria have to breakdown oxygen products?
Catalase, Peroxidase, and Superoxide dismutase
What is the function of catalase?
Breaks down hydrogen peroxide
What is an obligate aerobe?
Bacteria that use glycolysis, the Krebs TCA cycle, and the electron transport chain with oxygen as the final electron acceptor
What are facultative anaerobes?
Aerobic bacteria that use oxygen as electron transfer chain but they can grow in the absence of oxygen using fermentation for energy
*faculty to be anaerobic but prefer aerobic conditions
What are aero-tolerant anaerobe (microaerophilic) bacteria?
Bacteria that use fermentation and have no electron transport system but can tolerate low amounts of oxygen
What are obligate anaerobes?
Bacteria that have no enzymes to defend against oxygen
Can’t survive with oxygen
What do all medically important bacteria use for energy?
Chemical and organic compounds such as glucose
*called chemoheterotrophs
What is the most common fermentation pathway?
Embden-Meyerhof pathway
What happens in the Embden-Meyerhof pathway?
Glucose breakdown into lactic acid, ethanol, propionic acid, butyric acid, and acetone for bacteria to use for oxygen metabolism
How do obligate intracellular organisms obtain ATP?
Stealing from their host because they are not capable of metabolic pathways for ATP synthesis
