0.5 Glossary

• 454 sequencing (pyrosequencing) a next generation sequencing technique in which fragmented DNA has DNA adapters attached, is amplified by PCR, is attached to a bead, and then placed into a well with sequencing reagents, and the flash of light produced by the release of pyrophosphate on addition of a nucleotide is monitored
• 5’ cap methylguanosine nucleotide added to 5’ end of a eukaryotic primary transcript
• 70S ribosome a ribosome composed of 50S and 30S subunits
• 80S ribosome cytoplasmic eukaryotic ribosome composed of 60S and 40S subunits

A

• α-helix secondary structure consisting of a helix stabilized by hydrogen bonds between nearby amino acid residues in a polypeptide
• A (aminoacyl) site functional site of an intact ribosome that binds incoming charged aminoacyl tRNAs
• A-B exotoxin class of exotoxin that contains A subunits, which enter the cell and disrupt cellular activities, and B subunits, which bind to host cell receptors
• ABO blood group system set of glycoprotein antigens found on the surface of red blood cells; the presence or absence of specific carbohydrates determining blood type
• absorbance when a molecule captures energy from a photon and vibrates or stretches, using the energy
• Acanthamoeba keratitis a condition characterized by damage to the cornea and possible blindness caused by parasitic infection of the protozoan Acanthamoeba
• acellular not made of cells
• acid-fast stain a stain that differentiates cells that have waxy mycolic acids in their gram-positive cell walls
• acidic dye a chromophore with a negative charge that attaches to positively charged structures
• acidophile organism that grows optimally at a pH near 3.0
• acne a skin disease in which hair follicles or pores become clogged, leading to the formation of comedones and infected lesions
• acquired immunodeficiency syndrome (AIDS) disease caused by HIV, characterized by opportunistic infections and rare cancers
• actin a protein that polymerizes to form microfilaments
• activation energy energy needed to form or break chemical bonds and convert a reactant or reactants to a product or products
• activator protein that increases the transcription of a gene in response to an external stimulus
• active carrier an infected individual who can transmit the pathogen to others regardless of whether symptoms are currently present
• active immunity stimulation of one’s own adaptive immune responses
• active site location within an enzyme where substrate(s) bind
• acute disease disease of a relatively short duration that develops and progresses in a predictable pattern
• acute glomerulonephritis inflammation of the glomeruli of the kidney, probably resulting from deposition of immune complexes and an autoimmune response caused by self-antigen mimicry by a pathogen
• acute necrotizing ulcerative gingivitis a severe form of gingivitis, also called trench mouth
• acute otitis media inflammatory disease of the middle ear resulting from a microbial infection
• acute rheumatic fever sequela of streptococcal pharyngitis; comorbidities include arthritis and carditis
• acute-phase proteins antimicrobial molecules produced by liver cells in response to pathogen-induced stimulation events
• acyclovir antiviral guanosine analog; inhibits DNA replication
• adaptive immunity third-line defense characterized by specificity and memory
• Addison disease autoimmune disease affecting adrenal gland function
• adenine purine nitrogenous base found in nucleotides
• adenosine diphosphate (ADP) nucleotide derivative and relative of ATP containing only one high-energy phosphate bond
• adenosine monophosphate (AMP) adenine molecule bonded to a ribose molecule and to a single phosphate group, having no high-energy phosphate bonds
• adenosine triphosphate (ATP) energy currency of the cell; a nucleotide derivative that safely stores chemical energy in its two high-energy phosphate bonds
• adhesins molecules on the surface of pathogens that promote colonization of host tissue
• adhesion the capability of microbes to attach to host cells
• aerobic respiration use of an oxygen molecule as the final electron acceptor of the electron transport system
• aerotolerant anaerobe organism that does not use oxygen but tolerates its presence
• affinity maturation function of the immune system by which B cells, upon re-exposure to antigen, are selected to produce higher affinity antibodies
• affinity measure of how tightly an antibody-binding site binds to its epitope
• aflatoxin chemical produced by the fungus Aspergillus flavus ; both a toxin and the most potent known natural carcinogen
• African sleeping sickness see human African trypanosomiasis
• agarose gel electrophoresis a method for separating populations of DNA molecules of varying sizes by differential migration rates caused by a voltage gradient through a horizontal gel matrix
• agglutination binding of different pathogen cells by Fab regions of the same antibody to aggregate and enhance elimination from body
• agranulocytes leukocytes that lack granules in the cytoplasm
• alarmone small intracellular derivative of a nucleotide that signals a global bacterial response (i.e., activating a regulon of operons) to an environmental stress
• albendazole antihelminthic drug of the benzimidazole class that binds to helminthic β-tubulin, preventing microtubule formation
• algae (singular: alga) any of various unicellular and multicellular photosynthetic eukaryotic organisms; distinguished from plants by their lack of vascular tissues and organs
• alkaliphile organism that grows optimally at pH above 9.0
• alkylating agent type of strong disinfecting chemical that acts by replacing a hydrogen atom within a molecule with an alkyl group, thereby inactivating enzymes and nucleic acids
• allergen antigen capable of inducing type I hypersensitivity reaction
• allergy hypersensitivity response to an allergen
• allograft transplanted tissue from an individual of the same species that is genetically different from the recipient
• allosteric activator molecule that binds to an enzyme’s allosteric site, increasing the affinity of the enzyme’s active site for the substrate(s)
• allosteric site location within an enzyme, other than the active site, to which molecules can bind, regulating enzyme activity
• allylamines class of antifungal drugs that inhibit ergosterol biosynthesis at an early point in the pathway
• Alphaproteobacteria class of Proteobacteria that are all oligotrophs
• alveoli cul-de-sacs or small air pockets within the lung that facilitate gas exchange
• amantadine antiviral drug that targets the influenza virus by preventing viral escape from endosomes upon host cell uptake, thus preventing viral RNA release and subsequent viral replication
• amensalism type of symbiosis in which one population harms the other but remains unaffected itself
• Ames test method that uses auxotrophic bacteria to detect mutations resulting from exposure to potentially mutagenic chemical compounds
• amino acid a molecule consisting of a hydrogen atom, a carboxyl group, and an amine group bonded to the same carbon. The group bonded to the carbon varies and is represented by an R in the structural formula
• aminoacyl-tRNA synthetase enzyme that binds to a tRNA molecule and catalyzes the addition of the correct amino acid to the tRNA
• aminoglycosides protein synthesis inhibitors that bind to the 30S subunit and interfere with the ribosome’s proofreading ability, leading to the generation of faulty proteins that insert into and disrupt the bacterial cytoplasmic membrane
• amoebiasis intestinal infection caused by Entamoeba histolytica
• amoebic dysentery severe form of intestinal infection caused by Entamoeba histolytica , characterized by severe diarrhea with blood and mucus
• amphipathic a molecule containing both polar and nonpolar parts
• amphitrichous having two flagella or tufts of multiple flagella, with one flagellum or tuft located at each end of the bacterial cell
• amphotericin B antifungal drug of the polyene class that is used to treat several systemic fungal infections
• amplitude the height of a wave
• anabolism chemical reactions that convert simpler molecules into more complex ones
• anaerobe chamber closed compartment used to handle and grow obligate anaerobic cultures
• anaerobe jar container devoid of oxygen used to grow obligate anaerobes
• anaerobic respiration use of a non-oxygen inorganic molecule, like CO ₂ , nitrate, nitrite, oxidized iron, or sulfate, as the final electron acceptor at the end of the electron transport system
• analytical epidemiology study of disease outbreaks to establish associations between an agent and a disease state through observational studies comparing groups of individuals
• anaphylactic shock another term for anaphylaxis
• anaphylaxis systemic and potentially life-threatening type I hypersensitivity reaction
• anergy peripheral tolerance mechanism that prevents self-reactive T cells from being activated by self-antigens through lack of co-stimulation
• annealing formation of hydrogen bonds between the nucleotide base pairs of two single-stranded complementary nucleic acid sequences
• anoxygenic photosynthesis type of photosynthesis found in many photosynthetic bacteria, including the purple and green bacteria, where an electron donor other than H ₂ O is used to replace an electron lost by a reaction center pigment, resulting no oxygen production
• anthrax a disease caused by Bacillus anthracis ; the cutaneous form causes a skin lesion to develop; gastrointestinal and inhalation anthrax have high mortality rates
• antibiogram compilation of the antimicrobial susceptibilities recorded for local bacterial strains, which is useful for monitoring local trends in antimicrobial resistance and aiding the prescription of appropriate empiric antibacterial therapy
• antibiotic-associated diarrhea diarrhea that develops after antibiotic treatment as a result of disruption to the normal microbiota; C. difficile is a particularly serious example
• antibody screen test to make sure that a potential blood recipient has not produced antibodies to antigens other than the ABO and Rh antigens
• antibody Y-shaped glycoprotein molecule produced by B cells that binds to specific epitopes on an antigen
• antibody-dependent cell-mediated cytotoxicity (ADCC) mechanism by which large pathogens are marked for destruction by specific antibodies and then killed by secretion of cytotoxins by natural killer cells, macrophages, or eosinophils
• anticodon three-nucleotide sequence of a mature tRNA that interacts with an mRNA codon through complementary base pairing
• antigen (also, immunogen) a molecule that stimulates an adaptive immune response
• antigenic able to stimulate an adaptive immune response
• antigenic drift form of slight antigenic variation that occurs because of point mutations in the genes that encode surface proteins
• antigenic shift form of major antigenic variation that occurs because of gene reassortment
• antigenic variation changing of surface antigens (carbohydrates or proteins) such that they are no longer recognized by the host’s immune system
• antigen-presenting cells (APC) macrophages, dendritic cells, and B cells that process and present foreign pathogen antigens for the purpose of activating T cells and adaptive immune defenses
• antimetabolites compounds that are competitive inhibitors for bacterial metabolic enzymes
• antimicrobial drugs chemical compounds, including naturally produced drugs, semisynthetic derivatives, and synthetic compounds, that target specific microbial structures and enzymes, killing specific microbes or inhibiting their growth
• antimicrobial peptides (AMPs) class of nonspecific, cell-derived chemical mediators with broad-spectrum antimicrobial properties
• antiparallel two strands of DNA helix oriented in opposite directions; one strand is oriented in the 5’ to 3’ direction, while the other is oriented in the 3’ to 5’ direction
• antisense RNA small noncoding RNA molecules that inhibit gene expression by binding to mRNA transcripts via complementary base pairing
• antisense strand transcription template strand of DNA; the strand that is transcribed for gene expression
• antisepsis protocol that removes potential pathogens from living tissue
• antiseptic antimicrobial chemical that can be used safely on living tissue
• antiserum serum obtained from an animal containing antibodies against a particular antigen that was artificially introduced to the animal
• apoenzyme enzyme without its cofactor or coenzyme
• apoptosis programmed and organized cell death without lysis of the cell
• arachnoid mater middle membrane surrounding the brain that produces cerebrospinal fluid
• arboviral encephalitis infection by an arthropod-borne virus that results in an inflammation of the brain
• arbovirus any of a variety of viruses that are transmitted by arthropod vectors
• archaea any of various unicellular prokaryotic microorganisms, typically having cell walls containing pseudopeptidoglycan
• Archaea domain of life separate from the domains Bacteria and Eukarya
• artemisinin antiprotozoan and antifungal drug effective against malaria that is thought to increase intracellular levels of reactive oxygen species in target microbes
• artery large, thick-walled vessel that carries blood from the heart to the body tissues
• Arthus reaction localized type III hypersensitivity
• artificial active immunity immunity acquired through exposure to pathogens and pathogen antigens through a method other than natural infection
• artificial passive immunity transfer of antibodies produced by a donor to another individual for the purpose of preventing or treating disease
• ascariasis soil-transmitted intestinal infection caused by the large nematode roundworm Ascaris lumbricoides
• ascocarps cup-shaped fruiting bodies of an ascomycete fungus
• ascospore asexual spore produced by ascomycete fungi
• ascus structure of ascomycete fungi containing spores
• asepsis sterile state resulting from proper use of microbial control protocols
• aseptic technique method or protocol designed to prevent microbial contamination of sterile objects, locations, or tissues
• aspergillosis fungal infection caused by the mold Aspergillus ; immunocompromised patients are primarily at risk
• asymptomatic carrier an infected individual who exhibits no signs or symptoms of disease yet is capable of transmitting the pathogen to others
• asymptomatic not exhibiting any symptoms of disease
• atomic force microscope a scanning probe microscope that uses a thin probe that is passed just above the specimen to measure forces between the atoms and the probe
• ATP synthase integral membrane protein that harnesses the energy of the proton motive force by allowing hydrogen ions to diffuse down their electrochemical gradient, causing components of this protein to spin, making ATP from ADP and P _i
• attachment binding of phage or virus to host cell receptors
• attenuation regulatory system of prokaryotes whereby secondary stem-loop structures formed within the 5’ end of an mRNA being transcribed determine both if transcription to complete the synthesis of this mRNA will occur and if this mRNA will be used for translation
• autoclave specialized device for the moist-heat sterilization of materials through the application of pressure to steam, allowing the steam to reach temperatures above the boiling point of water
• autocrine function refers to a cytokine signal released from a cell to a receptor on its own surface
• autograft tissue transplanted from a location on an individual to a different location on the same individual
• autoimmune disease loss of tolerance to self, resulting in immune-mediated destruction of self cells and tissues
• autoinducer signaling molecule produced by a bacterial cell that can modify the activity of surrounding cells; associated with quorum sensing
• autoradiography the method of producing a photographic image from radioactive decay; in molecular genetics the method allows the visualization of radioactively-labeled DNA probes that have hybridized to a nucleic acid sample
• autotroph organism that converts inorganic carbon dioxide into organic carbon
• auxotroph nutritional mutant with a loss-of-function mutation in a gene encoding the biosynthesis of a specific nutrient such as an amino acid
• avidity strength of the sum of the interactions between an antibody and antigen
• axon long projection of a neuron along which an electrochemical signal is transmitted
• azithromycin semisynthetic macrolide with increased spectrum of activity, decreased toxicity, and increased half-life compared with erythromycin