Final Exam Flashcards
pathogens enter the cell via what?
Adherence
Bacterial Adherence can be facilitated by what?
Extracellular macromolecules not covalently bonded to the bacterial cell surface (Fimbriae & Pili)
Invasion of a pathogen is through what?
Epithelium Layer of the skin
During invasion, how does a pathogen enhance its virulence?
breaking down or altering host tissue to provide access to nutrients
How does an infecting pathogen protect itself from the hosts immune system?
by incorporating some part of the host cell into itself, tricking the host immune system
Name all of the Exotoxins covered in class
1) Cytolytic Toxins
2) A-B Type Toxins
3) Enterotoxins
Cytolytic toxin mechanism
degrade cytoplasmic membrane, causing cell lysis and death
A-B Type Toxin Mechanism
1) B subunit binds to a specific molecule on the host cell
2) toxin is taken up via endocytosis
3) toxin subunits seperate allowing (A) subunit (toxin) to enter the cytoplasm
3 Types of A-B Toxin
1) Diphtheria
2) Tetanus
3) Botulinum
Botulism mechanism
blocks the release of Acetylcholine, inhibiting contraction
Tetanus Mechanism
binds to inhibitory interneurons, preventing release of glycine and relaxation of the muscles
Diphtheria mechanism
causes protein synthesis to stop
What do enterotoxins do?
Mess with the ion balance in the gut epithelium
Endotoxins do what?
infect the lipopolysaccharide portion of the cell
How can you detect Endotoxins?
LAL assay
What do Type III Secretion pathogens do?
induce apoptosis
How do Type III Secretion pathogens enter the cell?
mess with actin polymerization
What is innate immunity?
No previous exposure
What does the innate immune system have the ability to do?
non-inducible ability to recognize and destroy an individual pathogen or its products
Adaptive Immunity
dependent on previous exposure
what does the adaptive immune system have the ability to do?
acquired ability to recognize and destroy a particular pathogen or its products
Adaptive Immunity Mechanism
1) recognize the pathogen antigen
2) T and B cells activated
Antibody Mechanism
B cells display antibodies on their surfaces that directly interact w/ antigen to cause B cells to ingest pathogen via phagocytosis
Ig proteins do what?
interact w/ antigenic determinants
Ig proteins are found where?
milk. serum, and gastric secretions
Major Histocompatibility Complex are what?
proteins that are expressed on the cell surface that reflect the composition of the protein inside the cell
Relationship between MHC and TCR
TCRs bind only to MHC molecules having foreign antigens embedded in the MHC structure
T cell Receptor
molecule found on the surface of T cells that is responsible for recognizing antigens bound to Major Histocompatibility complex (MHC) molecules
What is Inflammation?
a non-specific reaction to noxious stimuli
What mediates inflammation
Cytokines and Chemokines
What does inflammation do?
Isolates and limits tissue damage and destroys damaged cells as well as the pathogen
Mechanism of inflammation?
1) Interleukins attract Neutrophiles
2) activated neutrophiles release chemokines to recruit macrophages by guiding them along the chemkine gradient
What are Cytokines?
proteins that allow for intracellular communication in the immune system
What are Chemokines
Small group of proteins that function as chemoattractants for phagocytes and lymphocytes
What is Somatic Recombination?
Mechanism that creates diversity of T and B cells
How does Somatic Recombination work?
During development of B cells in the bone marrow, heavy chains and light chains are rearranged to create various combinations
What is compliment fixation?
The binding of active serum complement to an antigen-antibody pair.
Cloning Selection, T cells must?
be able to distinguish between themselves and nonself antigens
Tolerance
T cell is unresponsive to itself, meaning it can ID cells that dont belong in the host
Cloning selection Theory
each antigen-reactive B and T cell has a cell surface receptor for a single antigen epitope
Positive Selection
T cells that recognize MHC peptides are retained
Negative Selection
T cells that pass the positive selection and strongly bind to self antigens are selected against
T and B cell activation require what?
2 molecular signals
1) 1st signal interacts w/ antigen through Ig or TCRs
2) 2nd signal is necessary for them to respond to antigen
Selective Media
allows some organisms to grow while inhibiting others
Differential Media
allows identification of organisms based on their growth and appearance on the medium
Enteretube
a multiple-test system which combines 9 biochemical tests, useful in the identification of members of the family Enterobacteroaceae
Agglutination
visible clumping of a particular antigen when mixed w/ antibodies specific for the particular antigen (blood group tests)
Red Florescence
rhodamine D
Yellow-Green Florescence
flourescein isothiocyanate
Radioimmunoassay (RIA)
Uses radioisotope (iodine-125) as antibody or antigen conjugate instead of enzyme
Enzyme Immunoassay (EIA)
Direct Detect Antigen (color = positive)
Indirect Detect Antigen (color= positive)
Competitive Detect Antigen (color= negative)
Western Blotting
Detects antigens themselves or antibodies to specific antigens
Probe Technology
uses complimentary bp’s of probe to bind to DNA and RNA
