| AB toxins | The structure and activity of many exotoxins are based on the AB model. In this model, the B portion of the toxin is responsible for toxin binding to a cell but does not directly harm it. The A portion enters the cell and disrupts its function.
(See 797)
|
 |
|
|
| accessory pigments | Photosynthetic pigments such as carotenoids and phycobiliproteins that aid chlorophyll in trapping light energy.
(See 196)
|
|
|
|
| acetyl coenzyme A (acetyl-CoA) | A combination of acetic acid and coenzyme A that is energy rich; it is produced by many catabolic pathways and is the substrate for the tricarboxylic acid cycle, fatty acid biosynthesis, and other pathways.
(See 183)
|
|
|
|
| acid dyes | Dyes that are anionic or have negatively charged groups such as carboxyls.
(See 27)
|
|
|
|
| acid fast | Refers to bacteria like the mycobacteria that cannot be easily decolorized with acid alcohol after being stained with dyes such as basic fuchsin.
(See 543)
|
|
|
|
| acid-fast staining | A staining procedure that differentiates between bacteria based on their ability to retain a dye when washed with an acid alcohol solution.
(See 28)
|
|
|
|
| acidophile (as_id-o-føõl__) | A microorganism that has its growth optimum between about pH 0 and 5.5.
(See 123)
|
|
|
|
| acquired enamel pellicle | A membranous layer on the tooth enamel surface formed by selectively adsorbing glycoproteins (mucins) from saliva. This pellicle confers a net negative charge to the tooth surface.
(See 934)
|
|
|
|
| acquired immune deficiency syndrome (AIDS) | An infectious disease syndrome caused by the human immunodeficiency virus and is characterized by the loss of a normal immune response, followed by increased susceptibility to opportunistic infections and an increased risk of some cancers.
(See 878)
|
|
|
|
| acquired immune tolerance | The ability to produce antibodies against nonself antigens while "tolerating" (not producing antibodies against) self-antigens.
(See 758)
|
|
|
|
| acquired immunity | Refers to the type of specific immunity that develops after exposure to a suitable antigen or is produced after antibodies are transferred from one individual to another.
(See 729)
|
|
|
|
| actinobacteria (ak²tùõ-no-bak-tøer-e-ah) | A group of gram-positive bacteria containing the actinomycetes and their high G 1 C relatives.
(See 541)
|
|
|
|
| actinomycete (ak²tùõ-no-mi_søet) | An aerobic, gram-positive bacterium that forms branching filaments (hyphae) and asexual spores.
(See 537)
|
|
|
|
| actinorhizae | Associations between actinomycetes and plant roots.
(See 682)
|
|
|
|
| activated sludge (sluj) | Solid matter or sediment composed of actively growing microorganisms that participate in the aerobic portion of a biological sewage treatment process. The microbes readily use dissolved organic substrates and transform them into additional microbial cells and carbon dioxide.
(See 659)
|
|
|
|
| activation energy | The energy required to bring reacting molecules together to reach the transition state in a chemical reaction.
(See 162)
|
|
|
|
| active carrier | An individual who has an overt clinical case of a disease and who can transmit the infection to others.
(See 854)
|
|
|
|
| active immunization | The induction of active immunity by natural exposure to a pathogen or by vaccination.
(See 764)
|
|
|
|
| active site | The part of an enzyme that binds the substrate to form an enzyme-substrate complex and catalyze the reaction. Also called the catalytic site.
(See 162)
|
|
|
|
| active transport | The transport of solute molecules across a membrane against an electrochemical gradient; it requires a carrier protein and the input of energy.
(See 101)
|
|
|
|
| acute carrier | See casual carrier.
(See 854)
|
|
|
|
| acute infections | Virus infections with a fairly rapid onset that last for a relatively short time.
(See 410)
|
|
|
|
| acute viral gastroenteritis | An inflammation of the stomach and intestines, normally caused by Norwalk and Norwalklike viruses, other caliciviruses, rotaviruses, and astroviruses.
(See 891)
|
|
|
|
| acyclovir (a-si_klo-vir) | A synthetic purine nucleoside derivative with antiviral activity against herpes simplex virus.
(See 821)
|
|
|
|
| adenine (ad_e-nøen) | A purine derivative, 6-aminopurine, found in nucleosides, nucleotides, coenzymes, and nucleic acids.
(See 217)
|
|
|
|
| adenosine diphosphate (ADP; ah-den_o-søen) | The nucleoside diphosphate usually formed upon the breakdown of ATP when it provides energy for work.
(See 155)
|
|
|
|
| adenosine 5_-triphosphate (ATP) | The triphosphate of the nucleoside adenosine, which is a high energy molecule or has high phosphate group transfer potential and serves as the cell's major form of energy currency.
(See 155)
|
|
|
|
| adhesin (ad-he_zin) | A molecular component on the surface of a microorganism that is involved in adhesion to a substratum or cell. Adhesion to a specific host tissue usually is a preliminary stage in pathogenesis, and adhesins are important virulence factors.
(See 792)
|
|
|
|
| adjuvant (aj_@-v@nt) | Material added to an antigen to increase its immunogenicity. Common examples are alum, killed Bordetella pertussis, and an oil emulsion of the antigen, either alone (Freund's incomplete adjuvant) or with killed mycobacteria (Freund's complete adjuvant).
(See 741)
|
|
|
|
| adult T-cell leukemia | A type of white blood cell cancer caused by the HTLV-1 virus.
(See 887)
|
|
|
|
| aerobe (a_er-øob) | An organism that grows in the presence of atmospheric oxygen.
(See 127)
|
|
|
|
| aerobic anoxygenic photosynthesis | Photosynthetic process in which electron donors such as organic matter or sulfide, which do not result in oxygen evolution, are used under aerobic conditions.
(See 614)
|
|
|
|
| aerobic respiration (res²pùõ-ra_shun) | A metabolic process in which molecules, often organic, are oxidized with oxygen as the final electron acceptor. 154,
(See 173)
|
|
|
|
| aerotolerant anaerobes | Microorganisms that grow equally well whether or not oxygen is present.
(See 127)
|
|
|
|
| aflatoxin (af²lah-tok_sin) | A polyketide secondary fungal metabolite that can cause cancer.
(See 967)
|
|
|
|
| agar (ahg_ar) | A complex sulfated polysaccharide, usually extracted from red algae, that is used as a solidifying agent in the preparation of culture media.
(See 105)
|
|
|
|
| agglutinates | The visible aggregates or clumps formed by an agglutination reaction.
(See 775)
|
|
|
|
| agglutination reaction (ah-gloo²tùõ-na_shun) | The formation of an insoluble immune complex by the cross-linking of cells or particles.
(See 756)
|
|
|
|
| agglutinin (ah-gloo²tùõ-nin) | The antibody responsible for an agglutination reaction.
(See 756)
|
|
|
|
| AIDS | See acquired immune deficiency syndrome.
(See 878)
|
|
|
|
| AIDS-related complex (ARC) | A collection of symptoms such as lymphadenopathy (swollen lymph glands), fever, malaise, fatigue, loss of appetite, and weight loss. It results from an HIV infection and may progress to frank AIDS.
(See 879)
|
|
|
|
| airborne transmission | The type of infectious organism transmission in which the pathogen is truly suspended in the air and travels over a meter or more from the source to the host.
(See 854)
|
|
|
|
| akinetes | Specialized, nonmotile, dormant, thick-walled resting cells formed by some cyanobacteria.
(See 473)
|
|
|
|
| alcoholic fermentation | A fermentation process that produces ethanol and CO2 from sugars.
(See 179)
|
|
|
|
| alga (al_gah) | A common term for a series of unrelated groups of photosynthetic eucaryotic microorganisms lacking multicellular sex organs (except for the charophytes) and conducting vessels.
(See 571)
|
|
|
|
| algicide (al_jùõ-søõd) | An agent that kills algae.
(See 138)
|
|
|
|
| algology (al-gol_o-je) | The scientific study of algae.
(See 571)
|
|
|
|
| alkalophile | A microorganism that grows best at pHs from about 8.5 to 11.5.
(See 123)
|
|
|
|
| allergen (al_er-jen) | A substance capable of inducing allergy or specific susceptibility.
(See 768)
|
|
|
|
| allergic contact dermatitis | An allergic reaction caused by haptens that combine with proteins in the skin to form the allergen that produces the immune response.
(See 771)
|
|
|
|
| allergy (al_er-je) | See hypersensitivity.
(See 768)
|
|
|
|
| allograft (al_o-graft) | A transplant between genetically different individuals of the same species.
(See 773)
|
|
|
|
| allosteric enzyme (al_o-ster_ik) | An enzyme whose activity is altered by the binding of a small effector or modulator molecule at a regulatory site separate from the catalytic site; effector binding causes a conformational change in the enzyme and its catalytic site, which leads to enzyme activation or inhibition.
(See 165)
|
|
|
|
| allotype | Allelic variants of antigenic determinant(s) found on antibody chains of some, but not all, members of a species, which are inherited as simple Mendelian traits.
(See 734)
|
|
|
|
| alpha hemolysis | A greenish zone of partial clearing around a bacterial colony growing on blood agar.
(See 531, 797)
|
|
|
|
| alpha-proteobacteria | One of the five subgroups of proteobacteria, each with distinctive 16S rRNA sequences. This group contains most of the oligotrophic proteobacteria; some have unusual metabolic modes such as methylotrophy, chemolithotrophy, and nitrogen fixing ability. Many have distinctive morphological features.
(See 487)
|
|
|
|
| alternative complement pathway | An antibody-independent pathway of complement activation that includes the C3-C9 components of the classical pathway and several other serum protein factors (e.g., factor B and properdin).
(See 716)
|
|
|
|
| alveolar macrophage | A vigorously phagocytic macrophage located on the epithelial surface of the lung alveoli where it ingests inhaled particulate matter and microorganisms.
(See 711)
|
|
|
|
| amantadine (ah-man_tah-den) | An antiviral compound used to prevent type A influenza infections.
(See 821)
|
|
|
|
| amebiasis (amebic dysentery) (am²e-bi_ah-sis) | An infection with amoebae, often resulting in dysentery; usually it refers to an infection by Entamoeba histolytica.
(See 950)
|
|
|
|
| amensalism (a-men_s@l-iz-@m) | A relationship in which the product of one organism has a negative effect on another organism.
(See 609)
|
|
|
|
| American trypanosomiasis (Chagas' disease) | See trypanosomiasis.
(See 957)
|
|
|
|
| Ames test | A test that uses a special Salmonella strain to test chemicals for mutagenicity and potential carcinogenicity.
(See 253)
|
|
|
|
| amino acid activation | The initial stage of protein synthesis in which amino acids are attached to transfer RNA molecules.
(See 266)
|
|
|
|
| aminoacyl or acceptor site (A site) | The site on the ribosome that contains an aminoacyl-tRNA at the beginning of the elongation cycle during protein synthesis; the growing peptide chain is transferred to the aminoacyl-tRNA and lengthens by an amino acid.
(See 270)
|
|
|
|
| aminoglycoside antibiotics (am_ùõ-no-gli_ko-søõd) | A group of antibiotics synthesized by Streptomyces and Micromonospora, which contain a cyclohexane ring and amino sugars; all aminoglycoside antibiotics bind to the small ribosomal subunit and inhibit protein synthesis.
(See 816)
|
|
|
|
| amnesic shellfish poisoning (am-ne_sik) | The disease arising in humans and animals that eat seafood such as mussels contaminated with domoic acid from diatoms. The disease produces short-term memory loss in its victims.
(See 580)
|
|
|
|
| amoeboid movement | Moving by means of cytoplasmic flow and the formation of pseudopodia (temporary cytoplasmic protrusions of the cytoplasm).
(See 590)
|
|
|
|
| amphibolic pathways (am_fe-bol_ik) | Metabolic pathways that function both catabolically and anabolically.
(See 176)
|
|
|
|
| amphitrichous (am-fit_rùe-kus) | A cell with a single flagellum at each end.
(See 63)
|
|
|
|
| amphotericin B (am_fo-ter_i-sin) | An antibiotic from a strain of Streptomyces nodosus that is used to treat systemic fungal infections; it also is used topically to treat candidiasis.
(See 820)
|
|
|
|
| anabolism (ah-nab_o-lizm_) | The synthesis of complex molecules from simpler molecules with the input of energy.
(See 173)
|
|
|
|
| anaerobe (an-a_er-øob) | An organism that grows in the absence of free oxygen.
(See 127)
|
|
|
|
| anaerobic digestion (an_a-er-o_bik) | The microbiological treatment of sewage wastes under anaerobic conditions to produce methane.
(See 659)
|
|
|
|
| anaerobic respiration (an_a-er-o_bik) | An energy-yielding process in which the electron transport chain acceptor is an inorganic molecule other than oxygen.
(See 173)
|
|
|
|
| anammox process | The coupled use of nitrite as an oxidant and ammonium ion as a reductant under anaerobic conditions to yield nitrogen gas.
(See 616)
|
|
|
|
| anamnestic response (an_am-nes_tik) | The recall, or the remembering, by the immune system of a prior response to a given antigen.
(See 729, 743)
|
|
|
|
| anaphylaxis (an_ah-fùõ-lak_sis) | An immediate (type I) hypersensitivity reaction following exposure of a sensitized individual to the appropriate antigen. Mediated by reagin antibodies, chiefly IgE.
(See 768)
|
|
|
|
| anaplerotic reactions (an_ah-plùe-rot_ik) | Reactions that replenish depleted tricarboxylic acid cycle intermediates.
(See 216)
|
|
|
|
| anergy (an_@r-je) | A state of unresponsiveness to antigens. Absence of the ability to generate a sensitivity reaction to substances that are expected to be antigenic.
(See 758)
|
|
|
|
| annotation | The process of determining the location of specific genes in a genome map after it has been produced by nucleic acid sequencing.
(See 347)
|
|
|
|
| anogenital condylomata (venereal warts) (kon_dùõ-lo_ mah-tah) | Warts that are sexually transmitted and caused by types 6, 11, and 42 human papillomavirus. Usually occur around the cervix, vulva, perineum, anus, anal canal, urethra, or glans penis.
(See 894)
|
|
|
|
| anoxic (@-nok_ sik) | Without oxygen present.
(See 635)
|
|
|
|
| anoxygenic photosynthesis | Photosynthesis that does not oxidize water to produce oxygen; the form of photosynthesis characteristic of purple and green photosynthetic bacteria.
(See 199, 468)
|
|
|
|
| antheridium (an_ther-id_e-um; pl., antheridia) | A male gamete-producing organ, which may be unicellular or multicellular.
(See 561, 574)
|
|
|
|
| anthrax (an_thraks) | An infectious disease of animals caused by ingesting Bacillus anthracis spores. Can also occur in humans and is sometimes called woolsorter's disease.
(See 913)
|
|
|
|
| antibiotic (an_tùõ-bi-ot_ik) | A microbial product or its derivative that kills susceptible microorganisms or inhibits their growth.
(See 806)
|
|
|
|
| antibody (immunoglobulin) (an_tùõ-bod_e) | A glycoprotein produced in response to the introduction of an antigen; it has the ability to combine with the antigen that stimulated its production. Also known as an immunoglobulin (Ig).
(See 734)
|
|
|
|
| antibody-dependent cell-mediated cytotoxicity (ADCC) | The killing of antibody-coated target cells by cells with Fc receptors that recognize the Fc region of the bound antibody. Most ADCC is mediated by NK cells that have the Fc receptor or CD16 on their surface.
(See 723)
|
|
|
|
| antibody-mediated immunity | See humoral immunity.
(See 729)
|
|
|
|
| anticodon triplet | The base triplet on a tRNA that is complementary to the triplet codon on mRNA.
(See 266)
|
|
|
|
| antigen (an_tùõ-jen) | A foreign (nonself) substance (such as a protein, nucleoprotein, polysaccharide, or sometimes a glycolipid) to which lymphocytes respond; also known as an immunogen because it induces the immune response.
(See 731)
|
|
|
|
| antigen-binding fragment (Fab) | "Fragment antigen binding." A monovalent antigen-binding fragment of an immunoglobulin molecule that consists of one light chain and part of one heavy chain, linked by interchain disulfide bonds.
(See 734)
|
|
|
|
| antigenic determinant site (epitope) | See epitope.
(See 731)
|
|
|
|
| antigenic drift | A small change in the antigenic character of an organism that allows it to avoid attack by the immune system.
(See 852)
|
|
|
|
| antigenic shift | A major change in the antigenic character of an organism that alters it to an antigenic strain unrecognized by host immune mechanisms.
(See 852)
|
|
|
|
| antigen-presenting cells | Antigen-presenting cells (APCs) are cells that take in protein antigens, process them, and present antigen fragments to B cells and T cells in conjunction with class II MHC molecules so that the cells are activated. Macrophages, B cells, dendritic cells, and Langerhans cells may act as APCs.
(See 745)
|
|
|
|
| antimetabolite (an_tùõ-mùe-tab_o-løõt) | A compound that blocks metabolic pathway function by competitively inhibiting a key enzyme's use of a metabolite because it closely resembles the normal enzyme substrate.
(See 812)
|
|
|
|
| antimicrobial agent | An agent that kills microorganisms or inhibits their growth.
(See 139)
|
|
|
|
| antisense RNA | A single-stranded RNA with a base sequence complementary to a segment of another RNA molecule that can specifically bind to the target RNA and inhibit its activity.
(See 283)
|
|
|
|
| antisepsis (an²tùõ-sep_sis) | The prevention of infection or sepsis.
(See 138)
|
|
|
|
| antiseptic (an²tùõ-sep_tik) | Chemical agents applied to tissue to prevent infection by killing or inhibiting pathogens.
(See 138)
|
|
|
|
| antiserum (an_tùõ-se_rum) | Serum containing induced antibodies.
(See 742)
|
|
|
|
| antitoxin (an_tùõ-tok_sin) | An antibody to a microbial toxin, usually a bacterial exotoxin, that combines specifically with the toxin, in vivo and in vitro, neutralizing the toxin.
(See 756, 796)
|
|
|
|
| apical complex (ap_ùõ-kal) | A set of organelles characteristic of members of the phylum Apicomplexa: polar rings, subpellicular microtubules, conoid, rhoptries, and micronemes.
(See 591)
|
|
|
|
| apicomplexan (a_pùõ-kom-plek_san) | A sporozoan protist that lacks special locomotor organelles but has an apical complex and a spore-forming stage. It is either an intra- or extracellular parasite of animals; a member of the phylum Apicomplexa.
(See 591)
|
|
|
|
| aplanospore (a_plan-o-spor) | A nonflagellated, nonmotile spore that is involved in asexual reproduction.
(See 573)
|
|
|
|
| apoenzyme (ap_o-en_zøõm) | The protein part of an enzyme that also has a nonprotein component.
(See 161)
|
|
|
|
| apoptosis (ap²o-to_sis) | Programmed cell death. The fragmentation of a cell into membrane-bound particles that are eliminated by phagocytosis. Apoptosis is a physiological suicide mechanism that preserves homeostasis and occurs during normal tissue turnover. It is responsible for cell death in pathological circumstances, such as exposure to low concentrations of xenobiotics and infections by HIV and various other viruses. Apoptotic cells display profound structural changes such as plasma membrane blebbing and nuclear collapse. DNA is cleaved into short oligonucleosomal length DNA fragments. Apoptosis usually occurs after the activation ofr calcium-dependent endogenous endonuclease.
(See 750, 881)
|
|
|
|
| aporepressor | An inactive form of the repressor protein, which becomes the active repressor when the corepressor binds to it.
(See 276)
|
|
|
|
| arbuscular mycorrhizal (AM) fungi | The mycorrhizal fungi in a symbiotic fungus-root association that penetrate the outer layer of the root, grow intracellularly, and form characteristic much-branched hyphal structures called arbuscules.
(See 681)
|
|
|
|
| arbuscules | Branched, treelike structures formed in cells of plant roots colonized by endotrophic mycorrhizal fungi.
(See 681)
|
|
|
|
| Archaea | The domain that contains procaryotes with isoprenoid glycerol diether or diglycerol tetraether lipids in their membranes and archaeal rRNA (among many differences).
(See 424, 451)
|
|
|
|
| arthroconidium (ar_thro-ko-nid_e-um; pl., arthroconidia) | A thallic conidium released by the fragmentation or lysis of hypha. It is not notably larger than the parental hypha, and separation occurs at a septum.
(See 557)
|
|
|
|
| arthrospore (ar_thro-spøor) | A spore resulting from the fragmentation of a hypha.
(See 557)
|
|
|
|
| artificially acquired active immunity | The type of immunity that results from immunizing an animal with a vaccine. The immunized animal now produces its own antibodies and activated lymphocytes.
(See 730)
|
|
|
|
| artificially acquired passive immunity | The type of immunity that results from introducing into an animal antibodies that have been produced either in another animal or by in vitro methods. Immunity is only temporary.
(See 731)
|
|
|
|
| ascocarp (as_ko-karp) | A multicellular structure in ascomycetes lined with specialized cells called asci in which nuclear fusion and meiosis produce ascospores. An ascocarp can be open or closed and may be referred to as a fruiting body.
(See 561)
|
|
|
|
| ascogenous hypha | A specialized hypha that gives rise to one or more asci.
(See 561)
|
|
|
|
| ascogonium (as²ko-go_ne-um; pl., ascogonia) | The receiving (female) organ in ascomycetous fungi which, after fertilization, gives rise to ascogenous hyphae and later to asci and ascospores.
(See 561)
|
|
|
|
| ascomycetes (as²ko-mi-se_tøez) | A division of fungi that form ascospores.
(See 560)
|
|
|
|
| ascospore (as_ko-spor) | A spore contained or produced in an ascus.
(See 558)
|
|
|
|
| ascus (as_kus) | A specialized cell, characteristic of the ascomycetes, in which two haploid nuclei fuse to produce a zygote, which immediately divides by meiosis; at maturity an ascus will contain ascospores.
(See 561)
|
|
|
|
| aseptic meningitis syndrome | See meningitis.
(See 902)
|
|
|
|
| aspergillosis (as²per-jil-o_sis) | A fungal disease caused by species of Aspergillus.
(See 948)
|
|
|
|
| assimilatory reduction | The reduction of an inorganic molecule to incorporate it into organic material. No energy is made available during this process.
(See 210, 211, 614)
|
|
|
|
| associative nitrogen fixation | Nitrogen fixation by bacteria in the plant root zone (rhizosphere).
(See 675)
|
|
|
|
| athlete's foot | See tinea pedis.
(See 944)
|
|
|
|
| atomic force microscope | A type of scanning probe microscope that images a surface by moving a sharp probe over the surface at a constant distance; a very small amount of force is exerted on the tip and probe movement is followed with a laser.
(See 38)
|
|
|
|
| ATP-binding cassette transporters (ABC transporters) | Membrane protein complexes that use ATP energy to move substances across membranes without modifying the compound being transported. They require an extracytoplasmic substrate-binding protein for proper function.
(See 101)
|
|
|
|
| attenuation (ah-ten²u-a_shun) | 1. A mechanism for the regulation of transcription of some bacterial operons by aminoacyl-tRNAs. 2. A procedure that reduces or abolishes the virulence of a pathogen without altering its immunogenicity.
(See 281, 766)
|
|
|
|
| attenuator | A rho-independent termination site in the leader sequence that is involved in attenuation.
(See 279)
|
|
|
|
| autoclave (aw_to-kløav) | An apparatus for sterilizing objects by the use of steam under pressure. Its development tremendously stimulated the growth of microbiology.
(See 140)
|
|
|
|
| autogenous infection (aw-toj_e-nus) | An infection that results from a patient's own microbiota, regardless of whether the infecting organism became part of the patient's microbiota subsequent to admission to a clinical care facility.
(See 866)
|
|
|
|
| autoimmune disease (aw²to-ùõ-møun_) | A disease produced by the immune system attacking self-antigens. Autoimmune disease results from the activation of self-reactive T and B cells that damage tissues after stimulation by genetic or environmental triggers.
(See 772)
|
|
|
|
| autoimmunity (aw²to-ùõ-mun_ùõ-te) | Autoimmunity is a condition characterized by the presence of serum autoantibodies and self-reactive lymphocytes. It may be benign or pathogenic. Autoimmunity is a normal consequence of aging; is readily inducible by infectious agents, organisms, or drugs; and is potentially reversible in that it disappears when the offending "agent" is removed or eradicated.
(See 772)
|
|
|
|
| autolysins (aw-tol_ùõ-sins) | Enzymes that partially digest peptidoglycan in growing bacteria so that the peptidoglycan can be enlarged.
(See 223)
|
|
|
|
| autotroph (aw_to-trøof) | An organism that uses CO2 as its sole or principal source of carbon.
(See 96)
|
|
|
|
| auxotroph (awk_so-trøof) | A mutated prototroph that lacks the ability to synthesize an essential nutrient and therefore must obtain it or a precursor from its surroundings.
(See 245)
|
|
|
|
| axial filament | The organ of motility in spirochetes. It is made of axial fibrils or periplasmic flagella that extend from each end of the protoplasmic cylinder and overlap in the middle of the cell. The outer sheath lies outside the axial filament.
(See 66, 479)
|
|
|
|
| bacillus (bah-sil_lus) | A rod-shaped bacterium.
(See 43)
|
|
|
|
| bacteremia (bak_ter-e_me-ah) | The presence of viable bacteria in the blood.
(See 793)
|
|
|
|
| Bacteria (bak-te_re-@) | The domain that contains procaryotic cells with primarily diacyl glycerol diesters in their membranes and with bacterial rRNA. Bacteria also is a general term for organisms that are composed of procaryotic cells and are not multicellular.
(See 424)
|
|
|
|
| bacterial artificial chromosome (BAC) | A cloning vector constructed from the E. coli F-factor plasmid that is used to clone foreign DNA fragments in E. coli.
(See 335)
|
|
|
|
| bacterial (septic) meningitis | See meningitis.
(See 902)
|
|
|
|
| bacterial vaginosis (bak-te_re-@l vaj_ùõ-no_sis) | Bacterial vaginosis is a sexually transmitted disease caused by Gardnerella vaginalis, Mobiluncus spp., Mycoplasma hominis, and various anaerobic bacteria. Although a mild disease it is a risk factor for obstetric infections and pelvic inflammatory disease.
(See 914)
|
|
|
|
| bactericide (bak-tøer_ùõ-sid) | An agent that kills bacteria.
(See 138)
|
|
|
|
| bacteriochlorophyll (bak-te_re-o-klo_ro-fil) | A modified chlorophyll that serves as the primary light-trapping pigment in purple and green photosynthetic bacteria.
(See 199)
|
|
|
|
| bacteriocin (bak-te_re-o-sin) | A protein produced by a bacterial strain that kills other closely related strains.
(See 297, 712, 972)
|
|
|
|
| bacteriophage (bak-te_re-o-føaj_) | A virus that uses bacteria as its host; often called a phage.
(See 364, 382)
|
|
|
|
| bacteriophage (phage) typing | A technique in which strains of bacteria are identified based on their susceptibility to a variety of bacteriophages.
(See 842)
|
|
|
|
| bacteriostatic (bak-te_re-o-stat_ik) | Inhibiting the growth and reproduction of bacteria.
(See 138)
|
|
|
|
| bacteroid (bak_tùe-roid) | A modified, often pleomorphic, bacterial cell within the root nodule cells of legumes; after transformation into a symbiosome it carries out nitrogen fixation.
(See 676)
|
|
|
|
| baeocytes | Small, spherical, reproductive cells produced by pleurocapsalean cyanobacteria through multiple fission.
(See 475)
|
|
|
|
| balanced growth | Microbial growth in which all cellular constituents are synthesized at constant rates relative to each other.
(See 114)
|
|
|
|
| balanitis (bal_ah-ni_tis) | Inflammation of the glans penis usually associated with Candida fungi; a sexually transmitted disease.
(See 950)
|
|
|
|
| barophilic (bar_o-fil_ik) or barophile | Organisms that prefer or require high pressures for growth and reproduction.
(See 129, 644)
|
|
|
|
| barotolerant | Organisms that can grow and reproduce at high pressures but do not require them.
(See 129, 624)
|
|
|
|
| basal body | The cylindrical structure at the base of procaryotic and eucaryotic flagella that attaches them to the cell.
(See 64, 90)
|
|
|
|
| base analogs | Molecules that resemble normal DNA nucleotides and can substitute for them during DNA replication, leading to mutations.
(See 246)
|
|
|
|
| basic dyes | Dyes that are cationic, or have positively charged groups, and bind to negatively charged cell structures. Usually sold as chloride salts.
(See 27)
|
|
|
|
| basidiocarp (bah-sid_e-o-karp_) | The fruiting body of a basidiomycete that contains the basidia.
(See 561)
|
|
|
|
| basidiomycetes (bah-sid_e-o-mi-se_tøez) | A division of fungi in which the spores are born on club-shaped organs called basidia.
(See 561)
|
|
|
|
| basidiospore (bah-sid_e-o-spøor) | A spore born on the outside of a basidium following karyogamy and meiosis.
(See 558)
|
|
|
|
| basidium (bah-sid_e-um; pl., basidia) | A structure that bears on its surface a definite number of basidiospores (typically four) that are formed following karyogamy and meiosis. Basidia are found in the basidiomycetes and are usually club-shaped.
(See 561)
|
|
|
|
| basophil (ba_so-fil) | A phagocytic leukocyte whose granules stain bluish-black with a basic dye. It has a segmented nucleus. The granules contain histamine and heparin.
(See 707)
|
|
|
|
| batch culture | A culture of microorganisms produced by inoculating a closed culture vessel containing a single batch of medium.
(See 113)
|
|
|
|
| B cell, also known as a B lymphocyte | A type of lymphocyte derived from bone marrow stem cells that matures into an immunologically competent cell under the influence of the bursa of Fabricius in the chicken and bone marrow in nonavian species. Following interaction with antigen, it becomes a plasma cell, which synthesizes and secretes antibody molecules involved in humoral immunity. 705,
(See 751)
|
|
|
|
| B-cell antigen receptor (BCR) | A transmembrane immunoglobulin complex on the surface of a B cell that binds an antigen and stimulates the B cell. It is composed of a membrane-bound immunoglobulin, usually IgD or a modified IgM, complexed with another membrane protein (the Ig-a/Ig-b heterodimer).
(See 751)
|
|
|
|
| benthic (ben_thic) | Pertaining to the bottom of the sea or another body of water.
(See 571)
|
|
|
|
| beta hemolysis | A zone of complete clearing around a bacterial colony growing on blood agar. The zone does not change significantly in color.
(See 532, 797)
|
|
|
|
| b-oxidation pathway | The major pathway of fatty acid oxidation to produce NADH, FADH2, and acetyl coenzyme A.
(See 192)
|
|
|
|
| beta-proteobacteria | One of the five subgroups of proteobacteria, each with distinctive 16S rRNA sequences. Members of this subgroup are similar to the alpha-proteobacteria metabolically, but tend to use substances that diffuse from organic matter decomposition in anaerobic zones.
(See 495)
|
|
|
|
| binal symmetry | The symmetry of some virus capsids (e.g., those of complex phages) that is a combination of icosahedral and helical symmetry.
(See 376)
|
|
|
|
| binary fission | Asexual reproduction in which a cell or an organism separates into two cells.
(See 490, 573, 586)
|
|
|
|
| binomial system | The nomenclature system in which an organism is given two names; the first is the capitalized generic name, and the second is the uncapitalized specific epithet.
(See 426)
|
|
|
|
| biochemical oxygen demand (BOD) | The amount of oxygen used by organisms in water under certain standard conditions; it provides an index of the amount of microbially oxidizable organic matter present.
(See 657)
|
|
|
|
| biodegradation (bi_o-deg_rah-da_shun) | The breakdown of a complex chemical through biological processes that can result in minor loss of functional groups, fragmentation into larger constitutents, or complete breakdown to carbon dioxide and minerals. Often the term refers to the undesired microbial-mediated destruction of materials such as paper, paint, and textiles.
(See 1010)
|
|
|
|
| biofilms | Organized microbial systems consisting of layers of microbial cells associated with surfaces, often with complex structural and functional characteristics. Biofilms have physical/chemical gradients that influence microbial metabolic processes. They can form on inanimate devices (catheters, medical prosthetic devices) and also cause fouling (e.g., of ships' hulls, water pipes, cooling towers).
(See 620, 920)
|
|
|
|
| biogeochemical cycling | The oxidation and reduction of substances carried out by living organisms and/or abiotic processes that results in the cycling of elements within and between different parts of the ecosystem (the soil, aquatic environment, and atmosphere).
(See 611)
|
|
|
|
| bioinsecticide | A pathogen that is used to kill or disable unwanted insect pests. Bacteria, fungi, or viruses are used, either directly or after manipulation, to control insect populations.
(See 1018)
|
|
|
|
| biologic transmission | A type of vector-borne transmission in which a pathogen goes through some morphological or physiological change within the vector.
(See 858)
|
|
|
|
| bioluminescence (bi_o-loo_mùõ-nes_@ns) | The production of light by living cells, often through the oxidation of molecules by the enzyme luciferase.
(See 505)
|
|
|
|
| biomagnification | The increase in concentration of a substance in higher-level consumer organisms.
(See 618)
|
|
|
|
| biopesticide | The use of a microorganism or another biological agent to control a specific pest.
(See 1018)
|
|
|
|
| bioremediation | The use of biologically mediated processes to remove or degrade pollutants from specific environments. Bioremediation can be carried out by modification of the environment to accelerate biological processes, either with or without the addition of specific microorganisms.
(See 1012)
|
|
|
|
| biosensor | The coupling of a biological process with production of an electrical signal or light to detect the presence of particular substances.
(See 1017)
|
|
|
|
| biosynthesis | See anabolism.
(See 173)
|
|
|
|
| bioterrorism | The intentional or threatened use of viruses, bacteria, fungi, or toxins from living organisms to produce death or disease in humans, animals, and plants.
(See 863)
|
|
|
|
| biotransformation or microbial transformation | The use of living organisms to modify substances that are not normally used for growth.
(See 1009)
|
|
|
|
| black peidra (pe-a_drah) | A fungal infection caused by Piedraia hortae that forms hard black nodules on the hairs of the scalp.
(See 943)
|
|
|
|
| blastomycosis (blas²to-mi-ko_sis) | A systemic fungal infection caused by Blastomyces dermatitidis and marked by suppurating tumors in the skin or by lesions in the lungs.
(See 946)
|
|
|
|
| blastospore (blas_to-spøor) | A spore formed by budding from a hypha.
(See 557)
|
|
|
|
| B lymphocyte | See B cell.
(See 705, 751)
|
|
|
|
| botulism (boch_oo-lizm) | A form of food poisoning caused by a neurotoxin (botulin) produced by Clostridium botulinum serotypes A-G; sometimes found in improperly canned or preserved food.
(See 929)
|
|
|
|
| bright-field microscope |
