MLT 107: Ch.1 Bacterial Cell structure, physiology, metabolism, and genetics
Type of stain: Stains nucleic acid of both GP and GN bacteria Used to locate bacteria in blood cultures and other specimens where background material obscures gram stains
Acridine Orange
Atmospheric Requirements: organism that grow better in the absence of oxygen
Aerotolerant anaerobes
Term for an organism that grows in high temperatures 50-60 C
Thermophiles
Types of Eukaryotes
fungi, algae, protozoa, animal cells, plant cells
when using gram stain, cell stains pink
gram negative
when using gram stain, cell stains purple
gram positive
Plasmid
• Extra piece of DNA • Code for antibiotic resistance and other virulence factors are often found on plasmids • Sometimes passed from one bacterial species to another. This is how resistance is acquired.
Respiration (Oxidation)
• More efficient energy-generating process • Molecular oxygen is the final electron acceptor • Aerobic process in obligate aerobes and facultative anaerobes
Nutritional requirements for growth: Heterotrophs
• Require more complex substances for growth • Require an organic source of carbon and obtain energy by oxidizing or fermenting organic substances • All human bacteria fall in this category
Prokaryotes
- no organelles -unicellular - no membrane-bound nucleus -single, circular DNA chromosome - have both cell (plasma) membrane and cell wall
Archaebacteria
- resembles eukaryotes -found in microorganisms that grow under extreme environmental conditions - Cell wall lacks peptidoglycan
Shapes of bacteria: rod-shaped
Bacilli
Taxonomy (species): Term for biochemical test result differences
Biovarieties (biovar)
Bacterial Growth Media Types: used to detect small numbers of aerobes, anaerobes and microaerophiles
Broths
Taxonomy: Genus names
Capitalized - When in print, genus and species are italicized. - When written, genus and species are underlin
Taxonomy: Family names
Capitalized with "aceae" endings
Atmospheric Requirements: organisms grow better with extra CO2
Capnophilic
Shapes of bacteria: spherical
Cocci
Bacterial Growth Media Types: contains additives that allow visualization of metabolic differences in bacteria
Differential medium
Shapes of bacteria: cocci in pairs
Diplococci
Metabolic Pathways for conversion of glucose to pyruvate
Embden-Meyerhoff-Parnas (EMP) Pentose Phosphate pathway Entner-Doudoroff pathway
Bacterial Growth Media Types: nutrient medium with extra growth factors, such as blood which encourages small numbers of organisms to flourish
Enriched medium
Atmospheric Requirements: organism that can grow with or without oxygen
Facultative anaerobes
Cell appendages: sticky, hairlike projections that aid in attachment to other bacteria or surfaces
Fimbriae
Cell appendages: exterior protein filaments that rotate and cause bacteria to be motile
Flagella
Gram Stain Method
He CIAS - heat fix (methanol) -Crystal violet -Iodine -Alcohol-acetone -Safranin
Type of stain: negative stain for capsules, surrounds certain yeasts
India Ink
Taxonomy: name the seven classifications after "domain"
Kingdom, Phylum, Class, Order, Family , Genus, Species
Main oxidative pathway is the _____.
Krebs cycle aka. tricarboxylic acid cycle (TCA cycle)
Slime Layer
Made of polysaccharides - Inhibit phagocytosis - Aid in adherence to host tissue or implants
Term for an organism that grows in moderate temperatures 20-40 C
Mesophiles
Type of stain: stain for Corynebacterium diphtheriae to show metachromatic granules and as counter-stain in acid-fast stain procedures
Methylene Blue
Atmospheric Requirements: organisms grow better in low oxygen environments
Microaerophilic
Types of flagella
Monopolar, bipolar, peritrichous
Shapes of bacteria: coffee-bean shape in pairs
Neisseriae
Bacterial Growth Media Types: more complex, made of extracts of meat or soy beans
Nutrient medium
Atmospheric Requirements: organism that requires oxygen
Obligate aerobes
Atmospheric Requirements: organism that cannot grow in the presence of oxygen
Obligate anaerobes
Viruses: require host cells for replication and are usually host and/ or host cell specific
Obligate intracellular parasite
Gram Negative (GN) Cell Wall
PINK Two layers; inner layer is much thinner than GP cell walls - contains lipid A, o antigen, and porin Outer membrane functions: - Acts as a barrier to hydrophobic compounds and harmful substances -Acts as a sieve, allows water-soluble molecules to enter through porins - Enhances attachment to host cells
Gram Positive (GP) Cell Wall
PURPLE • Very thick protective peptidoglycan layer • Many GP antibiotics act by preventing synthesis of peptidoglycan • contain teichoic acid and lipoteichoic acid (LTA)
Taxonomy (species): Term for based on susceptibility to specific bacterial phages
Phage typing
Cell appendages: connect bacteria and mediate DNA exchange
Pili
Capsule (bacteria)
Protect the bacteria from phagocytosis - Capsule usually does not stain, but can appear as a clear area (halo-like)
Bacterial Growth Media Types: contains additives that inhibit the growth of some bacteria while allowing others to grow
Selective medium
Taxonomy (species): Term for serologic differences
Serovarieties (serovar)
Shapes of bacteria: helical
Spirochetes
Taxonomy: Species names
Staphylococcus sp. is used when referring to the genus when the species is not identified. Can be referred to as singular or plural - "sp." - singular (Staphylococcus sp.) - "spp." - plural (Staphylococcus spp.) Abbreviations - First letter of the genus, followed by a period and the species epithet - Ex: Staphylococcus aureus changes to S. aureus
Taxonomy (species): Term for phenotypic differences
Subspecies (subsp.)
Bacterial Growth Media Types: holding medium to preserve those bacteria present but does not allow multiplication
Transport medium
Acid Fast Cell Wall
mainly Mycobacteria and Nocardia - Have a GP cell wall structure but ALSO a waxy layer of glycolipids and fatty acids (mycolic acid) -Waxy layer makes them difficult to gram stain - Cannot be decolorized by acid-alcohol, hence the name "acid fast" - Incorporates Carbolfuchsin and acid-alcohol decolorizer
Absence of a Cell Wall
mainly Mycoplasma and Ureaplasma - Lack of cell wall results in a variety of shapes microscopically
Three methods of gene transfer
transformation, transduction (foreign DNA is introduced into a bacterial cell by a virus or viral vector), conjugation (temporary union of two bacteria or unicellular organisms for the exchange of genetic material)
Nutritional requirements for growth: Autotrophs
• Able to grow simply, using only CO2 , water and inorganic salts • Obtain energy via photosynthesis or oxidation of inorganic compounds • Occur in nature and do not normally cause disease
Fermentation
• Anaerobic process in obligate and facultative anaerobes • The electron acceptor is an organic compound • Does NOT require oxygen • Less efficient in generation of energy