Glossary
A
Abiogenesis The belief in spontaneous generation as a source of life.
Abiotic Nonliving factors such as soil, water, temperature, and light that
are studied when looking at an ecosystem.
Acid-Fast A term referring to the property of mycobacteria to retain carbol fuchsin even in the presence of acid alcohol. The staining procedure is used to diagnose tuberculosis
Actinomycetes A Group of filamentous, fungus like bacteria.
Active Immunity Immunity acquired through direct stimulation of the
immune system by antigen.
Acute Characterized by rapid onset and short duration
Adhesion The process by which microbes gain a more stable foothold at the portal of entry; often involves a specific interaction between the molecules on the microbial surface and the receptors on the host cell.
Aerobe A microorganism that lives and grows in the presence of free gaseous oxygen (O2)
Agar A polysaccharide found in seaweed and commonly used to prepare solid culture media.
Agglutination The aggregation by antibodies of suspended cells or similar-sized particles (agglutinogens) into clumps that settle.
Agranulocytes one form of leukocytes
Allergen a substance that Provokes an allergic response
Allergy the altered , usually exaggerated , immunie response to an allergen. Also called hypersensitivity
Anaerobe A microorganism that grows best , or exclusively , In the absence of oxygen
Anaphylaxis the unusual or exaggerated allergic reaction to antigen that leads to severe respiratory and cardiac complication.
Antigen any cell , particle , or chemical that induces a specific immune response by B cells or T cells and can stimulate resistance to an infection or a toxin. See immunogen.
Antigen Binding site specific region at the ends of antibody molecule that recognize specific antigens. These site have numerous shapes to fit a wide variety of antigens.
Antihistamine a drug that counters the action of histamine and is useful in allergy treatment
Antimicrobic a special class of compounds capable of destroying or inhibiting microorganisms.
Antiseptic A growth-inhibiting agent used on tissues to prevent infection.
Antitoxin Globulin fraction of serum that neutralizes a specific toxin. Also refers to the specific antitoxin antibody itself.
B
Bacillus Bacterial cell shape that is cylindrical ( longer than it is wide )
Bacteremia the presence of viable bacteria in circulating blood.
Bacterial Chromosome a circular body in bacteria that contains the primary genetic material. Also called nucleoid.
Bactericide an agent that kills bacteria
Biotic living factors such as parasites , food substrates , or other living or once-living organisms that are studied when looking at an ecosystem.
B Lymphocyte ( B Cell ) a white blood cell that gives rise to plasma cell and antibodies.
Booster the additional doses of vaccine antigen administered to increase an immune response and extend protection.
Broad spectrum a word to denote drugs that affect many different types of bacteria , both gram-positive and gram-negative
C
Capsule in bacteria , the loose , gel-like covering or slime made chiefly of simple polysaccharides. This layer is protective and can be associated with virulence.
Carrier a person who harbors infections and inconspicuously spreads them to others. Also a chemical agent that can accept an atom , chemical radical , or subatomic particle from one compound and pass it on to another.
Cell-Mediated tye type of immune responses brought about by T Cells. Such as cytotoxic suppressor and helper effects.
Chemotaxis the tendency of organisms to move in response to a chemical gradient ( toward an attractant or to avoid adverse stimuli ).
Chemotroph organisms that oxidizes compounds to feed nutrients.
Chromosome the tightly coiled bodies in cells that are the primary sites of genes.
Class in the levels of classification , the division of organism that follows phylum.
Colony a macroscopic cluster of cells appearing on a solid medium , each arising from the multiplication of a single cell.
Colostrum the clear yellow early product of brest
Commensalism an unequal relationship in which one species derives benefit without harming the other.
Communicable infection capable of being transmitted from one individual to another.
Community the interacting mixture of populations in a given habitat.
Complement in immunology , serum protein components that act in a definte sequence when set in motion either by an antigen-antibody complex or by factors of the alternative ( properdin ) pathway.
Conjugation in bacteria , the contact between donor and recipient cells associated with the transfer of genetic material such as plasmids. Can involve special ( SEX ) pili. Also a form of sexual recombination in ciliated protozoans.
Contagious communicable : transmissible by direct contact with infected people and their fresh secretions or excretions.
Contaminant an impurity : any undersirable material or organism.
Convalescence recovery : the period between the end of a disease and the complete restoration of health in a patient.
D
Definitive host the organism in which a parasite develops into its adult or sexually mature stage , also called final host.
Dimorphic in mycology , the tendency of some pathogens to alter their growth form from mold to yeast in response to rising temperature.
Diplococcus spherical or oval-shaped bacteria typically found in pairs.
Droplet nuclei the dried residue of fine droplets produced by mucus and saliv sprayed while sneezing and coughing. Droplet nuclei are less than 5 u,m in diameter ( large enough to bear a single bacterium and small enough to remain currents. Droplets nuclei are drawn deep into the air passages
Dysentery diarrheal illness caused by exotoxins.
Dyspnea Difficulty in breathing.
E
Endospore a small , dormant , resistant derivative of a bacterial cell that germinates under favorable growth conditions into a vegetative cell. The bacterial genera Bacillus and Clostridium are typical sporeformers.
Endotoxin a bacterial intracellular toxin that is not ordinarily released ( as is exotoxin ). Endotoxin is composed of a phospholipids-polysaccharide complex that is an integral part of gram-negative bacterial cell walls. Endotoxins can cause severe shock and fever.
Etiologic agent the microbial cause of disease : the pathogen.
Eucaryotic cell a cell that differs from a prokaryotic cell chiefly by having a nuclear memebrane ) a well-defined nucleus ), membrane bounded subcellular organelles , and mitotic cell division.
Exogenous originating outside the body.
Exotoxin a toxin ( usually protein ) that is secreted and act upon a specific cellular target. Examples: botulin , tetanospasmin , diphtheria toxin and erythrogenic toxin
Extremophiles organisms capable of living in harsh environment , such as extreme heat or cold.
F
Facultative pertaining to the capacity of microbes to adapt or adjust to variation : not obligate example : presence of oxygen is not obligatory for a facultative anaerobe to grow. See obligate.
Family in the levels of classification, a mid-level division of organisms than previous levels. An order is divided into families
Fermentation the extraction of energy through anaerobic degradation of substrates into simpler , reduced metabolities. In large inductrial processes, fermentation can mean any use of microbial metabolism to manufacture organic chemical or other products.
Flagellum a structure that is used to propel the organism through a fluid environment.
Flora beneficial or harmless resident bacteria commonly found on and / or in the human body.
Fomite virtually ani inanimate object an infected individual has contact with that can serve as a vehicle for the spread of disease.
G
Gene a site on a chromosome that provides information for certain cell function. A specific segment of DNA that contains the necessary code to make a protein or RNA molecule.
Generation time time required for a complete fission cycle --- from parent cell to two new daughter cells. Also called doubling time.
Genetics the science of heredity
Genus in the levels of classification, the second most specific level. A family is divided into several genera.
Germicide an agent lethal to non-endospore forming pathogens.
Giardiasis infection by the giardia flagellate.most common mode of transmission is contaminated food and water. Symptoms include diarrhea , abdomenial pain, and flatulence.
Gram stain a differential stain for bacteria useful in indentification and taxonomy. Gram-positive organisms appear purple from crystal violet and absorbance of the safranin counterstain.
H
Habitat the environment to which an organism is adapted.
Halophile a microbe whose growth is either stimulated by salt or requires a high concentration of salt for growth.
Herd immunity the status of collective acquired immunity in a population that reduces the likelihood that nonimmune individuals will contract and spread infection. One aim of vaccination is to induce herd immunity.
Heterotrph an organism that relies upon organic compound for its carbon and energy needs.
Histamine a cytokine released when mast cells and basophiles release their granules. An important mediator of allergy. Its effects include smooth muscle contraction, increased vascular permeability and increased mucus secretion.
Host organism in which smaller organisms or viruses live , feed and reproduce.
Human immunodeficiency virus ( HIV ) a retro virus that causes acquired immunodeficiency syndrome ( AIDS )
Humoral immunity protective molecules ( mostly B. lymphocytes ) carried in the fluids of the body.
Hyphae the tubular threads that make up filamentous fungi (molds). This web of branched and interwining fibers is called a mycelium.
I
Immunity an acquired resistance to an infectious agent due to prior contact with that agent.
Immunoglobulin the chemical class of proteins to which antibodies belong.
Immunology the study of the system of body defenses that protect against infection.
Immunopathology the study of disease states associated with overractivity or underreactivity of the immune response.
Infection the entry , establishment , and multiplication of pathogenic organisms within a host.
Infectious disease the state of damage or toxicity in the body caused by an infectious agent.
Inflammation a natural , nonspecific response to tissue injury that protects the host from further damage. It stimulates immune reactivity and blocks the spread of an infectious agent.
Inoculation the implantation of microorganisms into or upon culture media.
Interferon naturally occurring polypeptides produced by fibroblasts and lymphocytes that can block viral replication and regulate a variety of immune reactions.
Intoxication poisoning that results from the introduction of a toxin into the body tissues through ingestion or injection.
Isotonic two solutions having the same osmotic pressure such that , when separated by a semipermeable membrane, there is no net movement of solvent either direction.
Killer T Cells A t lymphocyte programmed to directly affix cells and kill them. See cytotoxic.
Kingdom in the levels of classification. The second division from more general to more specific. Each domain is divided into kingdoms.
Koch's Postulates a procedure to establish the specific cause of disease. In all cases infection : (1) the agent must be found : ( 2) inoculations of a pure culture must reproduce the same disease in animals ( 3) the agent must again be present in the experimental animals and ( 4 ) a pure culture must again be obtained.
L
Latency the state of being inactive. Example : a latent virus or latent infection.
Leukocytes white blood cells . the primary infection fighting blood cells.
Lymphatic system a system of vessels and organs that serve as sites for development of immune cells and immune reactions. It includes the spleen thymus , lymph nodes , and GALT.
Lymphocyte the second most common form of white blood cells.
Lymphokine a soluble substance secreted by sensitized T lymphocytes upon contact with specific antigen. About 50 types exist. And they stimulate inflammatory cells : macrophages granulocytes, and lymphocytes. Example : migration inhibitory factos , macrophage activating factos , chemotactic factor.
Lyse to burst
Lysis the physical rupture or deterioration of a cell.
Lysogeny the indefinite persistence of bacteriophage DNA in a host without bringing about the production of virions. A lysogenic cell can revert to a lytic cycle. The process that ends in lysis.
Lysosome a cytoplasmic organelle containing lysozyme and other hydrolytic enzymes
Lysozyme an enzyme that attacks the bond on bacterial peptidoglycan. It is natural defense found in tears and saliva.
M
Macrophage a white blood cell derived from a monocyte that leaves the circulation and enters tissues. These cells are important in nonspecific phagocytosis and in regulating , stimulating and cleaning up after immune responses.
Mast cell a nonmotile connective tissue cel implanted along capillaries, especially in the lungs , skin , gastrointestinal tract , and genitourinary tract. Like a basophile its granules store mediators of allergy.
Medium ( plural: media ) a nutrient used to grow organisms outside of their natural habitats
Memory cell the long-lived progeny of a sensitized lymphocyte that remains in circulation and its genetically programmed to react rapidly with its antigen.
Mesophile microorganisms that grow at intermediate temperature
Mesosome the irregular invagination of a bacterial cell membrane that is more prominent in gram-positive than in gram-negative bacteria. Although its function is not definitely known, it appears to participate in DNA replication and cell division: in certain cells. It appear to play a role in secretion.
Metabolism a general term for the totality of chemical and physical processes occurring in a cell.
Microaerophile an aerobic bacterium that requires oxygen at a concentration less than that in the atmosphere.
Microscopic invisible to the naked eye.
Mitochondrion a double-membrane organelle of eukaryotes that is the main site for aerobic respiration
Mixed culture a container growing two or more different known species of microbes
Monocyte a large mononuclear leukocyte normally found in the lymph nodes , spleen , bone marrow , and loose connective tissue. This type of cell makes up 3 % to 7 % of circulating leukocytes.
Morphology the study of organismic structure.
Mortality rate total number of death in a population attributable to a particular disease.
Motility self-propulsion.
Mycelium the filamentous mass that makes up a mold. Composed of hyphae.
Noncommunicable an infectious disease that does not arrive through transmission of an infectious agent from host to host.
Normal flora the native microbial forms that an individuals harbors.
Nosocomial infection an infection not present upon admission to a hospital but incurred while being treated there.
Nucleocapsid in viruses the close physical combination of the nucleic acid with its protective covering.
Nucleoid the basophilic nuclear region or nuclear body that contains the bacterial chromosome.
Nucleolus a granular mass containing RNA that is contained within the nucleus of a eukaryotic cells.
Nucleosome structure in the packaging of DNA. Formed by the DNA strands wrapping around the histone protein to form nucleus bodies arranged like beads on a chain.
Nucleus the central core of an atom, composed of protons and neutrons.
Nutrient any chemical substance that must be provided to a cell for normal metabolism and growth. Macronutrients are required in large amounts , and micronutrients in small amounts.
O
Obligate without alternative : restricted to a particular characteristic. Example : an obligate parasite survives and grows only in a host : an obligate aerobe must have oxygen to grow : an obligate anaerobe is destroyed by oxygen.
Opportunistic In infection , ordinarily nonpathogenic or weakly pathogenic microbes that cause disease primarily in an immunologically compromised host.
Order in the levels of classification, division of organisms that follows class. Increasing similarity may be noticed among organisms assigned to the same order.
Organelle a small component of eukaryotic cells that is bounded by a membrane and specialized in function.
Osmophile a microorganism that thrives in a medium having high osmotic pressure.
Osmosis the diffusion of water across a selectively permeable membrane in the direction of lower water concentration.
P
Palisades the characteristic arrangement of Corynebacterium cells resembling a row of fence posts and created by snapping.
Parasite an organism that lives on or within another organism ( the host ). From which it obtains nutrients and enjoys protection. The parasite produce some degree of harm in the host.
Passive immunity specific resistance that is acquired indirectly by donation of perfomed immune substances ( antibodies ) produced in the body of another individual.
Pasteurization heat treatment of perishable fluids such as milk. Fruit or wine to destroy heat-sensitive vegetable cells. Followed by rapid chilling to inhibit growth of survivors and germination of spores. It prevents infection and spoilage.
Pathogen any agent , usually a viruses , bacterium , fungus , protozoa , or helminth , that causes disease.
Pathogenicity the capacity of microbes to cause disease.
Pathology the structural and physiological effects of disease on the body.
Peptidoglycan a network of polysaccharide chains cross-liked by short peptides that forms the rigid part of bacterial cell calls. Gram-negative bacteria have a smaller amount of this rigid structure than do gram-positive bacteria.
Periplasmic space the egion between the cell wall and cell membrane of the cell envelopes of gram-negative bacteria.
Peritrichous in bacterial morphology , having flagella distributed over the entire cell.
pH the symbol for the negative logarithm of the H ion concentration : p ( power ) or [ H+ ] 10. a system for rating acidity and alkalinity.
Phage a bacteriophage : a virus that specifically parasitizes bacteria.
Phagocytosis a type of endocytosis in which the cell membrane actively engulfs large particles or cell into vesicles.
Phlebotomine Pertains to a genus of very small midges or blood-sucking ( phlebotomous ) sand flies and to disease associated with those vectors such as kala-azar , oroya-fever , and cutaneous leishmaniasis.
Photosynthesis a process occurring in plants , algae , and some bacteria that traps the sun's energy and converts it to ATP in the cell. This energy is used to fix Co2 into organic compounds.
Phototrophs microbes that use photosynthesis to feed.
Phylum in the levels of classification , the third level of classification from general to more specific . each kingdom is divided into numerous phyla sometimes referred to a division.
Physiology the study of the function of an organism
Pili small , stiff filamentous appendages in gram-negative bacteria that function in DNA exchange during bacterial conjugation.
Plasmids Extrachromosomal genetic units characterized by several features. A plasmid is a double-stranded DNA that is smaller than and replicates independently of the cell chromosome : it bears gene that are not essential for cell growth : it can bear genes that code for adaptive trails : and it is transmissible to other bacteria.
Pleomorphism normal variability of cell shapes in a single species.
Procaryotic cell small cells, lacking special structures such as nucleus and organelles . all prokaryotes are microorganisms.
Prophylactic any device , method or substance used to prevent disease.
Protozoa a group of single-celled , eukaryotic organisms.
Psychrophile a microorganism that thrives at low temperature ( O – 20 C ) with a temperature optimum of 0 – 15 C.
Pure culture a container of microbial cells whose identity is known.
Pus the viscous , opaque usually yellowish matter formed by an inflammatory infection. It consists of serum exudates , tissue debris , leukocytes and microorganisms.
R
Resident flora the deeper , more stable microflora that inhabit the skin and exposed mucous membranes , as opposed to the superficial variable , transient population.
Resolving power the capacity of a microscope lens system to accurately distinguish between two separate entities that lie close to each other. Also called resolution.
Ribosome a bilobed macromolecular complex of ribonucleoprotein that coordinates the codons of mRNA and tRNA anticodons and , in so doing constitutes the peptide assembly site.
Ringworm a superificial mycosis caused by various dermatophytic fungi. This common name is actually a misnomer.
S
Saccharide scientific term for sugar, refer to a simple carbhodrates with a sweet taste.
Sarcina A cubical packet of 8 , 16 or more cells: the cellular arrangement of the genus Sarcina in the family mircococcaceae.
Scientific method principles and procedures for the systematic pursuit of knowledge , involving the recognition and formulation of a problem , the collection of data through observation and experimentation, the formulation and testing of a hypothesis.
Selective media nutrient media designed to favor the growth certain microbes and to inhibit undersirable competitors.
Sepsis the state of putrefaction : the presence of pathogenic organisms or their toxins in tissue or blood.
Septic Shock blood infection resulting in a pathological state of low blood pressure accompanied by a reduced amount of blood circulating to vital organs , endotoxins of all gram-negative enteric rods.
Septicemia systemic infection associated with microorganisms multiplying in circulating blood.
Septum a partition of cellular cross wall , as in certain fungal hyphae.
Serum the clear fluid expressed from clotted blood that contains dissolved nutrients , antibodies and hormone but not cells or clotting factors.
Sex pilus a conjugation pilus
Solvent a dissolving medium
Spirillum a type of bacterial cell with a rigid spiral shape and external flagella.
Spirochete a coiled ,spiral shaped bacterium that has endoflagella and flexes as it moves.
Sporangium a fungal cell in which asexual spores are formed by multiple cell cleavage.
Spore a differentiated , specialized cell form that can be used for dissemination , for survival in times of adverse condition . and or / for reproduction. Spores are usually unicellular and may develop into gametes or vegetative organisms.
Sporozoite one of many minute elongated bodies generated by multiple division of the oocyst . it is the infectious form the malarial parasite that is harbored in the salivary gland of the mostquito and inoculated into the victim during feeding.
Sporulation the process of spore formation..
Sterile completely free of all life forms , including spores and viruses.
Sterilization any process that completely removes or destroys all viable microorganisms , including viruses , from an object or habitat. Material so treated is sterile.
Subacute indicates an intermediate status between acute and chronic disease.
Subclinical a period of inapparent manifestations that occurs before symptoms and signs of disease appear.
Subcutaneous the deepest level of the skin structure.
Substrate the specific molecule upon which an enzyme acts.
Suppressor T Cell a class of T cells that inhibits the actions of b cells and other t cells.
Symbiosis an intimate association between individuals from two species used as a synonym for mutualism.
Symptom the subjevtive evidence of infection and disease as perceived by the patient.
Systemic occuring throughout the body : said of infections that invades many compartments and organs via the circulation.
T
Tetanus a neuromuscular disease caused by infection with clostridium tetani. Usual portals of entry include puncture wounds , burns umbilical stumps , frostbite sites and crushed body parts vaccination repeated at the recommended time scan prevent infection . also called lockjaw.
Tetrads groups of four.
Theory a collection of statements , propositions or concepts that explains or account for a natural event.
Thermophile a microorganism that thrives at a temperature of 50 C or higher.
Tinea Ringworm , a fungal infection of hair , skin or nails.
T lymphocyte ( T cell ) a white blood cell that is processed in the thymus gland and is involved in cell-mediated immunity.
Toxemia an abnormality associated with certain infectious disease. . toxemia is caused by toxins or other noxious substances released by microorganism circulating in the blood.
Toxingencity the tendency for a pathogen to produce toxins it is an important factor in bacterial virulence .
Toxin a specific chemical product of microbes plants. And some animals that is poisonous to other organisms.
Toxoid a toxin that has been rendered nontixc but is still capable of eliciting the formation of protective antitoxin antibodies used in vaccines.
Trace Elements microbnutrients ( zinc , nickel , and manganese that occur in small amount and are involved in enzymes function and maintenance of protein structure.
Transients in normal flora , the assortment of superficial microbes whose numbers and types vary depending upon recent exposure. The deeper=lying residents constitute a more stable population.
Tyndallization fractional ( discontinuous , intermittent ) sterilization designed to destroy spores indirectly . a preparation is exposed to flowing steam for an hour, and then the mineral is allowed to incubate to permit spore germination. The resultant vegetative cells are destroyed by repeated steaming and incubation.
V
Vaccine originally used in reference to inoculation with the cowpox or vaccinia virus to protect against smallpox , in general the term now pertains to injfection of whole microbes ( killed or attenuated ) toxoids , or part of microbes as a prevention or cure disease.
Vacuoles in the cell , membrane-bounded sacs cointaining fluids or solid particles to be digested , excrete or stored.
Vector an animal that transmit infectious agents from one host to another , usually a biting or piercing arthropod like the thick , mosquito or fly infectious agents can be conveyed mechanically by simple contact or biologically whereby the parasite develops
Vegetative in describing microbial developmental stages , a metaboilically active feeding and dividing form as opposed to a dormant, seemingly inert, nondividing form examples: a bqcterial cell versus its spore : a protozoan trophozoite versus its cyst.
Vesicle a blister characterized by a thin-skinned elevated , superficial pocket inflated with serum.
Vibrio a curved rod-shaped bacterial cell.
Viremia the presence of a virus in the bloodstream.
Virion an elementary virus particle in its complete morphological and thus infectious form , a virion consists of the nucleic acid core surrounded by a capsid which can be enclosed in an envelop.
Virus microscopic acellular agent composed of nucleic acid surrounded by a protein coat.
Virulence in infection , relative capacity of a pathogen to invade and harm host cells.
Z
Zoonosis an infectious disease indigenous to animals that humans can acuire through direct or indirect contact with infected animals.
Zygospore a thick – walled sexual spore produced by the zygomycete fungi , it develops from the union of two hyphae. Each bring nuclei of opposite mating types.
