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MCB 3020
Final Exam
| Term | Definition |
|---|---|
| Koch (1881) | developed the idea that a specific microorganism causes a specific disease; three postulates: (1) microscopy, (2) sterilization and aseptic techniques, (3) pure culture methods. |
| gram + | one thick layer of peptidoglycan; amino acid of DAP is linked to carboxyl group of terminal D-alanine by peptide bond; has more crosslinks; most cocci have lysine instead of DAP |
| gram - | two layers (thin peptidoglycan and LPS); cross-linkage occurs by way of a peptide interbridge |
| protoplast experiment | in dilute solution, breakdown of cell wall releases the protoplast, but then immediately lyses. in isotonic solution, water does not enter the protoplast and therefore does not lyse. |
| reduction potentionals | written as reduction half reactions; standard conditions are at pH7; more negative donates electrons to the more positive; more positive - more negative; |
| electron tower | the farther the electrons drop from a donor before they are caught by an acceptor, the greater the amount of energy released. |
| faraday's constant | 23 kcal/volt |
| faraday's equation | G=-nFE |
| fueling - phase 1 | provides: energy (from oxidation of energy source in a complete redox reaction), C skeleton (12 intermediates [3 central pathways: EM, Krebb's, Pentose]), reducing power. |
| biosynthesis - phase 2 | uses the C skeletons to make subunits of macromolecules;12 key precursor metabolites that produce the correct #'d C skeletons: 20 amino acids, 4 Rnucleotides, 4 Dribonucleotides, monosacc, n-acetylglucosamine, n-acetylmuramic acid, fatty acids, glycerol |
| polymerization - phase 3 | consist of the directed, sequential linkage of activated molecules into long (branched?) chains; polymerization of building blocks into proteins, dna, rna, and glyco occur inside the cell where their assembly into LPS, capsule, murein are outside of cell |
| assembly - phase 4 | involve the chemical modification of macromolecules, their transport to prespecified locations in the cell, and their association to form cellular structures |
| ABC (atp-binding cassette) system | active transport; energy from atp; periplasmic binding protein; high affinity for substrate; membrane-spanning proteins: carrier or transmembrane protein that serves as a channel; g+ lack true periplasm |
| group translocation | active transport; chemical modification of solute as it is transported across the membrane; modification uses energy; driven by PEP; |
| simple diffusion | passive transport; non-saturable; driven by concentration gradient |
| facilitated diffusion | passive transport; facilitated by a carrier; saturation at high concentrations of solute (specificity for solute); driven by concentration gradient |
| anhydride | high energy bond |
| ester | low energy bond |
| high-energy phosphate bonds | in living organisms, chemical energy released in redox reactions is conserved in these bonds; function as the energy source to drive energy-requiring reactions in the cell |
| phosphate groups | are attached via oxygen atoms by ester or anhydride bonds; NOT all phosphate bonds are high-energy bonds |
| lag phase of bacterial growth | does not always occur in the growth of a bacterial population, and when it does, the duration can vary considerably; k=0; little to no growth; happens because cells need to synthesize all the necessary materials needed in the new environment |
| exponential or log phase of bacterial growth | can not continue indefinitely; limited k=max+; double every generation time |
| stationary phase of bacterial growth | k=0; no increase in cell number or cell mass; occurs because either an essential nutrient is used up or a waste product builds up to an inhibitory level |
| death phase of bacterial growth | k=-; exponential death (slower than exponential growth) |
| fermentation | involves glucose oxidation to pyruvate and the donation of hydrogens from NADH+ to pyruvate or a derivative of it; uses 2 atp to start; only 2 net atp produced by two slp steps; rate is fast; no oxygen; no atp from op; em pathway |
| anaerobic respiration | biological oxidation in which the terminal electron acceptor is usually inorganic molecule (external) other than oxygen(nitrate, sulfate, or carbon dioxide); uses oxidative phosphorylation for atp synthesis; |
| (free) endospores | resistant to heat, drying, disinfectants, acid, and radiation; can remain dormant for extremely long periods of time; bacteria are found most commonly in the soil; core of dipicolinic acid |
| acquired or induced immunity (resistance) | humoral immunity: mediated by antibodies; cellular immunity mediated by cells (T cells) |
| natural resistance (innate immunity) | cells: macrophages, etc.; mechanical barriers: skin and mucous membranes; chemical factors: interferons, fatty acids on skins; microbial factors |
| mechanical barriers of innate immunity | skin, mucous membranes, tears, and respiratory tract |
| chemical barrier of innate immunity | fatty acids (attack gram-); bile salts (inhibit gram+); lysozyme (more effective against gram+); interferon (active against viruses); phagocytins (found in white blood cells); complement (causes some cells to lose physical integrity and lyse) |
| microbial factors of innate immunity | normal flora of the body provides protection by competition with pathogens; if damaged by antibiotics, the individual may get a fungal infection |
| cellular factors of innate immunity | phagocytic cells may engulf microorganisms and destroy it. |
| phagocytes | can act as antigen-presenting cells (APCs) and generate a peptide antigen(s) that will activate specific immune responses; can use negatively charged O2 and various acids/enzymes to destroy pathogens |
| antibodies | B cells (lymphocytes) -> plasma cells -> Ab; synthesized by plasma cells in humoral response and are capable of combining with the provoking antigen |
| T-cells | T cells (lymphocytes) -> activated T-lymphocytes |
| CD4 T-helper (TH1 and TH2) | helps or induces an immune response; associated with MHC class II |
| CD8 t-cytotoxic cells | associated with MHC class 1 |
| characteristics of specific immunity | memory: capacity to respond more quickly and more vigorously after exposure to an antigen; tolerance: acquired inability to make an immune response to certain antigens |
| innate immunity results from | interactions between pathogen-associated molecular patterns (PAMPs) found as cell surface components and pattern recognition receptors (PRRs; called Toll receptors that were first observed in Drosophilia) found on phagocytes |
| Toll-like receptors on human phagocytes | recognize specific PAMPS and respond to interactions with LPS, a PAMP in outer membrane of gram - inducing phagocyte activation and immunity to gram - |
| interaction of PAMP with the phagocyte PRR | triggers a trans-membrane signal that results in transcription of a number of cell proteins in phagocyte; this leads to production of toxic oxygen compounds that lead to pathogen death |
| erythema | redness |
| edema | swelling |
| inflammation | typical outcome of an innate or an adaptive immune response; typically protective; effective response isolates and limits tissue damage |
| adaptive immunity | due to antigen specific T cells, resulting in two distinct effector pathways: antibodies or T cells |
| monocytes | myeloid precursor; develop into macrophages or dendritic cells that are phagocyte cells involved in antigen uptake and display |
| granulocytes (neutrophils, mast cells, eosinophils, and basophils) | myeloid precursor; neutrophils are phagocytes; the others release their granule contents in response to pathogens, pathogen products, or damaged host cells |
| T and B cells | lymphoid precursors |
| lymphoid precursor matures in thymus | T cell |
| lymphoid precursor matures in bone marrow or fetal liver | B cell |
| anamnestic | has memory; repeated contact with antigen amplifies response |
| immunogens | capable of eliciting an immune response; usually large protein or complex polysaccharides with high molecular weight(>10,000) in insoluble or aggregate form; foreign to responder; NOT all antigens are immunogens |
| toxoid | has its immunogenicity but has lost its toxicity |
| epitope (antigenic determinative) | the distinct portion of the antigenic macromolecule that interacts with the antibody or t cell receptors |
| antibody specificity | sensitive enough to distinguish between two very similar epitopes |
| major histocompatibility complex (MHC) | function as antigen presenting molecules and interact with both antigen and TCR; T-cell cannot recognize foreign antigen unless it is presented in context of an MHC protein |
| MHC I | found on surface of all nucleated cells; made in ER; protein antigens are degraded with cytoplasmic proteasome, transported across ER via a pore, bind to Class I and transported to bind with TCR, then T-cell releases cytotoxins/cytokines to kill cell |
| MHC II | found only on surface of B lymphocytes, macrophages, and dendritic cells, all dedicated antigen-presenting cells (APCs); made in ER but assembled with an invariant chain to prevent MHC II from complexing with peptides found in ER; |
| MHC II (part 2) | fuses with phagosomes to form phagolysosome to digest foreign cells; binds to digested foreign proteins and complex transported out of cell to bind to TCR and CD4 coreceptor on T helper cell |
| T-cytotoxic cell (Tc) | destroys cells that display antigens embedded in MHC I molecules; granulates migrate to contact site and contents released; uses perforin (forms pore to deliver toxic enzymes); uses granzymes that enter through pore and cause apoptosis; CD8 |
| T-helper cell 1 (Th1) | activated by antigens presented on macrophages in the context of MHC II; then produce cytokines that enhance macrophages to take up and kill certain foreign cells; secretes cytokine IL-2 which activates Tc cells; CD4 |
| T-helper cell 2 (Th2) | key role in B cell activation and antibody production; B cell coated with antibodies that act as antigen receptors; activated B cell directs different. into antibody producing plasma cells and other cytokines direct differentiation into memory cells; CD4 |
| immunoglobulins (Ig; antibodies) | protein molecules that are able to combine with epitopes; found in the serum and in other body fluids; 5 classes, of which 80% are IgG, all have VH (variable heavy) and VL (v. light) domains that bind antigens; have constant domains that define the class |
| anti-serum | serum containing antigen-specific antibody |
| papain | nonspecific thiol-endopeptidase; enzymatically cleaves IgG just above hinge region to create 2 separate Fab fragments and one Fc; Fab fragments bind antigen; |
| Fab | antibody fragment of immunoglobulins |
| Fc | crystallizable fragment of immunoglobulins |
| IgG (gamma) | composed of 4 polypeptide chains; interchain disulfide bridges connect the chains; consists of 2 antigen binding sites and therefore bivalent and can bind 2 identical epitopes; crosses the placental barrier; subclasses: gamma 1,2,3, 4; extracellular fluid |
| IgM (mu) | usually found as an aggregate of 5 molecules attached by at least one J chain; every heavy chain contains a 4th constant; 10 binding sites; low affinity but high avidity; monomers on B cell surface; IgM made first in response to infection; blood and lymph |
| IgA (alpha) | present in the serum in the monomeric form but in secretions it is a dimer; linked by disulfide bridges and J chain protein; secretory piece wrapped around dimer during secretion; total amount produced is 2x amount of IgG in serum; secretions (milk, etc.) |
| IgD (delta) | present in serum in low concentrations; has no known function; abundant on surfaces of B cells and plays a role along with IgM in binding antigen to B cells; blood and lymph |
| IgE (epsilon) | found in serum in very small amounts; mediates immediate (type 1) hypersensitivities (allergies); has a 4th constant domain which functions to bind to MAST cell surfaces (MAST cell degranulation causes release of histamine and serotonin); blood and lymph |
| lymphatic system | part of the immune system that is made up of a network of conduits that carry lymph around the body. |
| primary response to antigen introduction | initially, each antigen-stimulated B cell multiples and differenties to form both antibody secreting plasma cells and memory cells; plasma cells produce IgM; following a latent period, specific antibodies show up, then increase in titer, then slow fall. |
| secondary response to antigen introduction | memory cells generated may live for several years; upon re-exposure to the immunizing agent, memory cells don't need T-cell activation and can quickly transform to plasma cells and begin producing IgG; antibody titer rises rapidly(10-100x higher than 1st) |
| secondary antibody response (anamnestic) | the rise in antibody titer during the secondary response; characterized by a switch from IgM to IgG; over time titer slowly decreases but can increase upon later exposure; basis for booster shots |
| natural killer cells (NK) | innate; class of lymphoid cells that destroy host cells that harbor microbes or have been transformed into cancer cells; recognize changes in cell surface proteins of compromised cells; then degranulate to release chemicals that kill them |
| active immunity | antibodies made or T-cells activated in the individual upon contact with antigen; longer lasting memory cells; |
| artificial active immunity | individual purposely exposed to controlled dose of harmless antigen to induce artificial active immunity (vaccination) |
| passive immunity | cells or antibodies from an immune individual are transferred to a nonimmune individual to prevent or help cure a disease; short lived compared to active |
| vaccination | inoculation of host with inactive or weakened pathogens or pathogen products to stimulate immunity; can use: attenuated strains, chemically/physically inactivated strains, products of pathogens, recombinant vector vaccine, DNA vaccines |
| attenuation | attenuated strains of pathogens have lost virulence but often they retain immunogenicity, therefore may be used for production of vaccines; won't necessarily be beneficial for immunocompromised individuals |
| nosocomial infections | health-care associated infections; often antibiotic resistant |
| antimicrobial agent | natural or synthetic agent that kills or inhibits growth of microorganisms; if it kills it will end in -cidal (ex: fungicidal);if it inhibits growth, then -static; |
| chemotherapeutic agent | those used to treat microbial diseases and now also to prevent proliferation of malignant cells |
| antibiotics | compounds produced by one species of microbe that can kill or inhibit growth of other microbes |
| sterilization | treatment that frees the treated object of all living organisms, including viruses |
| death | defined as irreversible loss of ability to reproduce when inoculated into an appropriate medium or host; exponential function when heat is increased |
| autoclave | applies steam heat under pressure at temperatures above the boiling point of water, resulting in the killing of endospores; 15 lbs per sq. above atmospheric pressure at 121 degrees celsius for 15 minutes |
| pasteurization | does not sterilize liquids but reduces microbial load, killing most of pathogens and inhibiting the growth of spoilage microorganisms; 72 degrees celsius for 15 seconds through a tiny tube |
| in vitro disinfectants | chemicals that kill microorganisms but not necessarily spores |
| invitro sanitizers | reduce to safe levels |
| in vitro antiseptics/germicides | kill or inhibit growth but nontoxic enough to be applied to human tissue |
| first effective antimicrobial agent | Salvarsan (an arsenical compound), found by Ehrlick in 1909 |
| translation | the conversion of code to another; starts by positioning a tRNA with methionine onto the mRNA codon; needs 1 ATP to charge the tRNA, 1 GTP to control EF-Tu, and 1 GTP to control EF-G |
| mRNA code | is almost universal and the code is degenerate (more than one codon for most amino acids) |
| tRNA | has an "anti-codon" that is complementary to the mRNA codon |
| central dogma of molecular biology | DNA to RNA to proteins |
| gene | the nucleotide sequence coding for a single polypeptide chain, or ribosomal RNA, or a t-RNA |
| DNA contains introns and exons | first, methylated guanine nuclotide is added at the 5' phosphate end and the 3' end is trimmed by adding a poly A tail then, the introns must be removed and the exons spliced together by using spliceosome to make mature mRNA that is moved to the cytoplasm |
| Cytosine bonds with | Guanine |
| Thymine bonds with | Adenine |
| viruses | either DNA or RNA viroids; small pieces of RNA |
| plasmids | small genetic elements that exist and replicate separately from the major bacterial "chromosome"; most are circular polynucleotides that do not usually cause cell damage or have extra cellular forms |
| helicase (dnaB) | unwinds the DNA double helix; energy provided by ATP; |
| lytic cycle of viruses | virus replication occurs and the host is lysed |
| lysogenic cycle of viruses | the viral nucleic acid integrates into the host chromosome (called a prophage) and replicates when the host DNA replicates |
| latent infection | virus present but not causing harm to cell, but later emerges in lytic infection |
| persistent infection | slow release of virus without cell death |
| transformation infection | transformation into tumor cell and replication to form more tumor cells |
| retrovirus replication | uncoated ssRNA virus penetrates animal cells and the reverse transcriptase enzymes converts it into a complementary DNA that is converted to dsDNA which is integrated into host DNA |
| transformation | genetic transfer mediated by small pieces of double stranded extracellular DNA |
| generalized transduction | mediated by virus; pieces of host DNA enclosed in capsid and infects another host cell bringing in the new host genes |
| restricted transduction | mediated by virus; viral DNA integrated into host DNA; when induced, some bacterial genes are excised along with some viral genes and transferred to new host |
| conjugation | DNA transfer from donor to recipient cell mediated by cell to cell contact and sometimes bridge information like the F+ factor |
| 10x more bacteria than cells on the body | 10^13 human cells; 10^14 bacteria |
| mutualism | both host and microbe benefit; +/+ |
| commennsalism | microbe causes no damage to host; +/0 |
| parasitism | microbe causes damage to host; +/- |
| synergistically | capable of working together; two microorganisms are synergistic if they are able to produce a host response greater than the sum of the effects they produce when acting alone |
| communicable | able to be transmitted between hosts |
| disease reservoir | a natural source of disease agent; may include sick patients, asymptomatic carriers, animals, recovered patients, environmental sources, etc. |
| parasites | organisms that live on or in a host organism, causing damage to the host |
| pathogens | microbial parasites; some may be carried by healthy individuals but may not cause disease |
| pathogenicity | the ability of the parasite to cause damage on the host and on the resistance or susceptibility of the host to the parasite |
| virulence | the quantitative measure of degree of pathogenicity |
| comprised host | has lower resistance to infection and ultimately disease |
| infection | refers to any situation in which a microorganism is established and growing in or on a host, regardless of whether or not the host is harmed |
| disease | damage or injury to the host that impairs host function |
| infection is not | synonymous with disease |
| infestation | presence of microorganism; not necessarily growing and reproducing |
| normal flora of skin | 10^12 bacteria; apocrine (sweat) glands and sebaceous (oil) glands of hair follicles |
| normal flora of internal tissue | brain, blood, cerebrospinal fluid, and muscles should not have bacteria |
| normal flora of stomach | pH around 2; acidity drops viable count to <10/mL; mycobacteria and salmonella are resistant; helicobacter phlori causes ulcers |
| normal flora of colon | adult eliminates about 3 x 10^13 microbes daily |
| normal flora of genourinary tract | upper (kidney, ureters and urinary bladder) should not have microbes |
| normal flora of respiratory system | upper (nasopharynx, oral cavity, larynx and pharynx) have a restricted number of colonies; lower (trachea, bronchi, bronchioles, and alveoli) should not have bacteria |
| normal flora of epithelium cells | mucous traps move microbes up and out via cilia and excreted in saliva and nasal secretions; finally, bactericidal effect of lysozyme |
| portals of entry of microorganisms | food and water borne; exhalation droplets (coughing and sneezing onto dust particles); direct contact (sexual); indirect contact (hand to hand or hand to eye); animal bites or scratches; parenteral (wound or puncture); vector transmitted |
| adherence (I) | bacteria or viruses usually initiate infection by adhering specially to epithelial cells through interactions (fimbriae) between macromolecules on surfaces of the pathogen and host; often begin at sites in mucous membranes |
| tissue selective | microorganisms adhere to specific receptors on specific cells |
| host selectivity | a microorganism that normally infects humans binds to human epithelial cells better than those of a rat |
| fimbriae and pili | bacterial surface protein structures that also function in attachment (bind to host cell glycoproteins or complex lipids); |
| adherence (II) | microbe may penetrate through small breaks or lesions or even an intact mucosal surface |
| invasion (III) | invasion, especially if normal flora is altered, then microbe may establish itself, grow, and multiply. |
| colonization and growth (IV) | production of virulence factors and either produce toxin effects (local or systematic) or further growth that ultimately leads to tissue damage and disease |
| invasiveness | grow in large numbers and may spread throughout host body |
| toxigenicity | toxins that inhibit host cell function or kill host cells (endotoxins and exotoxins) |
| hyaluronidase | also called the spreading factor because it catalyzes the breakdown of hyaluronic acid, the substance that cements the human cells together; allows bacteria cells to spread through tissue causing cellulitis. |
| coagulase | catalyzes the conversion of fibrinogen to fibrin with the result being clot formation; present in pathogenic staphylococcus; allows bacteria to grow inside of the clot |
| fibrinolysin | catalyzes the conversion of plasminogen to the fibrinolytic enzyme plasmin; opposite of coagulase; allows the clot to dissolve and therefore spreading the bacteria |
| lipase | allows bacteria to penetrate fatty tissue with the consequent formation of abscesses |
| collagenase | catalyzes the degradation of collagen, a protein found in tendons, hair, and nails. |
| leukocidins | causes lysis of white blood cells; staphylococcus aureus |
| streptokinase and streptodornase | fibrinolytic enzymes |
| lecithinase | destroys red blood cells and other tissue cells |
| hemolysins | lyses red blood cells |
| Group A Streptococci (GAS) | enzymes to breakdown clots; enzymes to inhibit clotting machinery |
| clostridium perfringens | hyaluronidase and collagenase; food poisoning |
| gas gangrene | death and putrefaction of tissues, bubbles of gas in decomposing tissue; widespread and destroys tissue |
| LD50 | the dose of an agent that kills 50% of the animals in a test group |
| exotoxins | secreted by certain g+ or g- bacteria; often highly toxic, sometimes fatal; generally heat-liable; highly immunogenic (stimulates production of antibodies) |
| endotoxins | part of the LPS layer in g- bacteria that are released when the cell lyses; extremely heat stable; weakly toxic, rarely fatal; relatively poor immunogen; causes fever |
| pyrogenic | induces fever in host |
| pyogenic | induces pus formation |
| cytolytic exotoxins | damages cell membranes, causing cell lysis and death |
| A-B exotoxins | B promotes specific binding of toxin to host cell receptor to allow transfer of the toxic part, A, across the targeted cell membrane |
| superantigen exotoxins | stimulate large numbers of immune lymphocytes and causes systemic as well as inflammatory responses; extensive inflammation and tissue damage; |
| cytotoxins exotoxins | inhibit a cell function or cause cell death |
| neurotoxins exotoxins | inhibit nerve transmission |
| enterotoxins exotoxins | alter permeability of intestinal epithelium and then causes massive secretion of fluid into the intestinal lumen causing diarrhea |
| alpha toxin | a pore forming cytotoxin that is produced by growing stapylococcal cells; released a monomer with 7 subunits; pore releases the contents of the cell while bringing in extracellular material; causes cell to swell and lyse |
| anthrax | made of three parts where each individual anthrax toxin protein is in fact, nontoxic. |
Created by:
JacobGant
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