Immunity And Classification Flashcards
The 5 general characteristics to classify bacteria (and example of each)
- Macroscopic (colony morphology/ growth characteristics)
- Biochemical traits (production of certain end products/ use certain substrates/ selective media)
- Growth Requirements (anaerobic vs aerobic etc.)
- Microscopic (cell morphology/ differential strains)
- Specialized tests/ secretion pathways
Seven characteristics associated with colony morphology
“PEETOSS” Pigmentation Edge/margin Elevation Texture Optical Properties Size Shape
Three biochemical/ metabolic traits
- Utilization of specific substrates as a nutrient (lactose or citrate as energy source)
- Growth on differential/ selective media (hydrolytic patterns on blood agar)
- Production of certain end products (fermentation producing alcohol or acid)
Fastidious growth requirements
Picky eater- numerous nutrient requirements
Nonfastidious growth requirements
Will grow on anything
Microaerophile oxygen requirements
Utilizes some O2 but can’t be exposed to too much or will die
Aerotolerant oxygen requirement
Can live in O2 but doesn’t need it
Facultative oxygen requirement
Can live without oxygen but would grow better with it
Gram stain enables classification based on what?
Cell wall structure
Bacilli
Rod-shaped
Cocci
Spherical shaped
Spirilla
Spiral shaped
Vibrio
Curved
Spirochete
Thin spring, flexible and tightly coiled
Palisade
Bacilli lined up along each other like sardines
Coccobacilli
Rounded oval rectangular-ish shape
Diplo-bacilli
Two rods in a chain
Strepto
Three or more in a chain
Staphylo
Clusters
Molecular characteristics used for bacterial classification
OCR, Nucleic acid sequence analysis, restriction fragment length polymorphism (RFLP), DNA hybridization, Phage-GFP,
Type 3 Secretion pathway
Found in gram negative bacterial only, secretes proteins from cytoplasm into host cell. Contact dependent (injects toxin into host cell directly).
Secretion machinery is needle shaped and secreted proteins are thought to move through a translocation channel
Type 4 secretion pathway
Found in gram negative and gram positive, similar to conjugation system (secrets protein and transfers DNA during conjugation) can go bacteria to bacteria or bacteria to eukaryote. ATP dependent
Shortages bacterial secretion pathway
Found in gram positive bacteria, covalently attach proteins to cell wall following secretion, assist in survival during infection (attachment is first and most important part of infection)
Injectosome bacterial secretion pathway
Found in gram positive bacteria, similar to type 3 and 4 systems of gram negatives
Definition of immunity
The ability to ward off disease through body defenses
Characteristics of Innate immunity
Nonspecific resistance Routine protection Defenses against any pathogen Immediate response with no memory Refers to whatever defenses are present at the time
Characteristics of adaptive immunity
Pathogen-specific resistance Acquired during the lifetime Requires time to develop (2 exposures) Involves specialized cells Has memory
Characteristics of the first line of defense
Nonspecific natural barriers that restrict entry or means for physical removal of a pathogen (skin, mucous membranes and their secretions, normal micro flora)
Characteristics of the second line of defense
Nonspecific immune defenses that provide rapid local response to pathogen after it has entered the host (natural killer cells and phagocytic white blood cells- macrophages and neutrophils-, inflammation, fever, antimicrobial substances)
Skin chemicals in first line of defense, and their role
In perspiration: salt (hypertonic environment, antimicrobial peptides, lysozyme enzymes to destroy bacterial cell wall)
In sebum: keeps skin pliable and less likely to tear, lowers skin pH to a level damaging to most bacteria)
Three layers of mucous membranes and their uses
- Epithelium (thin, tightly packed outer covering, shedding to carry away microorganisms)
- Dendritic cells below epithelium to phagocytize pathogens and goblet/ ciliated columnar cells to remove invaders
- Deeper connective layer to support the epithelium- produces required chemicals
Lacrimal apparatus
(Tear production) continual washing and blinking to prevent microbes from settling on eye surface, plus lysozyme in tears to break down any particulate matter
Ciliary escalator
Cilia on mucous membranes of lower respiratory tract move upwards towards through at 1-3cm/ hour- raised up high enough so you can cough/ sneeze it up
Chemical defenses of mucus
Glycoproteins and water, thick, inhibits colonization by preventing critical mass
Chemical defenses of gastric juices
Acidic (pH 1-3 destroys most bacteria) contains enzymes and mucus
Chemical defenses of lysozyme
Enzyme in most body secretions that degrades peptidoglycan
Chemical defenses of transferrins
Iron binding proteins in blood which inhibit bacterial growth by reducing available iron (bacteria have a huge need for iron)
Microbial antagonism
Normal micro flora compete for resources with potential pathogens. May even produce antibiotic compounds toxic to non-native species
Eosinophils
Fight parasitic worms and are involved in allergic reactions. A type of granulocyte with cytoplasmic granules
Basophils
Involved in allergic reactions and inflammation (similar to mast cells, found in tissues) a type of granulocytes (cytoplasmic granules) release histamine and other inflammation causing chemicals from the granules
Neutrophils (PMN’s)
Account for most of the leukocytes, usually not seen in tissues except during inflammation. Phagocytize and digest engulfed materials
Lymphocyte (B and T cells)
Single nucleus (mostly nucleus with not much cytoplasm before differentiation) seen in lymph nodes/ spleen and tonsils and in circulation, participate in adaptive immune response
Monocytes
Single nucleus, lots of cytoplasm. Differentiate either into macrophages or dendritic cells. Will phagocytize and digest engulfed materials
Macrophages
Present in virtually all tissues. Given names based on what tissue they’re found in.
- Alveolar= lung
- Kupffer= liver
- Microglial= brain
- Histocyte= tissue
- Langerhans= skin/mucosa
Dendritic cells
Branched, in tissues but eventually migrate to lymph infection nodes/ organs. Gather antigen from tissues and present it to lymphocytes that congregate in secondary lymphoid organs, developing an adaptive response
Steps of phagocytosis
- Chemotaxis
- Recognition and attachment
- Engulfment
- Phagosome maturation/ phagolysosome formation
- Destruction and digestion
- Formation of residual body
- Exocytosis
Chemotaxis (phagocytosis)
Phagocytes recruited by chemoattractants produced by phospholipids form injured host cells, chemokines and C5a
Recognition and attachment (phagocytosis)
Direct (Pattern recognition receptors to PAMP or DAMP) or indirect (binding to opsonins)
PRR
Pattern recognition receptors on macrophages that detect pathogen-associated molecular patterns (PAMP), or danger-associated molecular patterns (DAMPs) aka host cell damage
Three types of PRR’s
- Toll-like receptors (internal or external antigen receptors) anchored in membranes
- NOD-like receptors, found internally only- in cytoplasm. Detect bacterial components indicating the cell has been breached.
- RIG-like receptors. Also found internally only- in the cytoplasm. Detect viral RNA, indicating infection. Will produce interferons
Engulfment (phagocytosis)
Pseudopods surround and a phagosome is formed
Phagosome maturation and phagolysosome formation (phagocytosis)
Endoscopes fuse, lower pH, lysosome brings digestive enzymes
Destruction and digestion (phagocytosis)
Toxic ROS and nitric oxide produced, pH decreases, enzymes degrade, defensins damage membrane of invader, lactoferrin ties up iron
Formation of the residual body (phagocytosis)
Indigestible material remaining in the phagolysosome