0.5 Glossary  (Page 3/18)

C

• Calvin-Benson cycle most common CO ₂ fixation pathway in most photoautotrophs; involves light-independent reactions of photosynthesis that occur in the cytoplasm of photosynthetic bacteria and in the stroma of eukaryotic chloroplasts
• Campylobacter jejuni gastroenteritis gastroenteritis caused by C. jejuni ; generally mild but sometimes with serious complications
• candidiasis fungal infection caused by Candida spp., especially C. albicans ; can affect various regions of the body, e.g., skin (cutaneous candidiasis), oral cavity (oral thrush), or vagina (yeast infection)
• candle jar container with a tight-fitting lid in which a burning candle consumes oxygen and releases carbon dioxide, thereby creating an environment suitable for capnophiles
• capillary small blood vessel found in the interstitial space of tissue; delivers nutrients and oxygen, and removes waste products
• capnophile organism that requires carbon dioxide levels higher than atmospheric concentration
• capsid protein coat surrounding the genome of the virus
• capsomere individual protein subunits that make up the capsid
• capsule staining a negative staining technique that stains around a bacterial capsule while leaving the capsule clear
• capsule type of glycocalyx with organized layers of polysaccharides that aid in bacterial adherence to surfaces and in evading destruction by immune cells
• carbapenem-resistant Enterobacteriaceae (CRE) group of bacteria that have developed resistance to all β-lactams, including carbapenems, and many other drug classes
• carbohydrate the most abundant type of biomolecule, consisting of carbon, hydrogen, and oxygen
• carbon skeleton chain of carbon atoms to which one or more functional groups are bound
• carboxysome an inclusion composed of an outer shell of thousands of protein subunits. Its interior is filled with ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and carbonic anhydrase, which are both used for carbon metabolism
• carbuncle abscess containing a large, deep, purulent skin lesion
• carcinogen agent that causes cancer
• case-control study a type of observational study in which a group of affected individuals are compared, usually retrospectively, to a similar group of unaffected individuals
• catabolic activator protein (CAP)/cAMP receptor protein (CRP) protein that, when bound to cAMP in the presence of low levels of glucose, binds to the promoters of operons that control the processing of alternative sugars
• catabolism chemical reactions that break down complex molecules into simpler ones
• catabolite repression repression of the transcription of operons encoding enzymes for the use of substrates other than glucose when glucose levels are high
• catalase enzyme that breaks down hydrogen peroxide to water and oxygen
• catalyst molecule that increases the rate of a chemical reaction but is not used or changed during the chemical reaction and, thus, is reusable
• catarrhal stage in pertussis, a disease stage marked by inflammation of the mucous membranes combined with excessive secretions
• cat-scratch disease bacterial infection of the lymph nodes caused by Bartonella henselae ; frequently transmitted via a cat scratch
• causative agent the pathogen or substance responsible for causing a particular disease; etiologic agent
• CCA amino acid binding end region of a mature tRNA that binds to an amino acid
• celiac disease disease largely of the small intestine caused by an immune response to gluten that results in the production of autoantibodies and an inflammatory response
• cell envelope the combination of external cellular structures (e.g., plasma membrane, cell wall, outer membrane, glycocalyces) that collectively contain the cytoplasm and internal structures of a cell
• cell membrane lipid bilayer with embedded proteins and carbohydrates that defines the boundary of the cell (also called the cytoplasmic membrane or plasma membrane)
• cell morphology cell shape, structure, and arrangement, as viewed microscopically
• cell theory the theory that all organisms are composed of cells and that the cell is the fundamental unit of life
• cell wall a structure in the cell envelope of some cells that helps the cell maintain its shape and withstand changes in osmotic pressure
• cellular immunity adaptive immunity involving T cells and the destruction of pathogens and infected cells
• cellulitis a subcutaneous skin infection that develops in the dermis or hypodermis, resulting in a red, painful inflammation
• cellulose a structural polysaccharide composed of glucose monomers linked together in a linear chain by glycosidic bonds
• Centers for Disease Control and Prevention (CDC) the national public health agency in the United States
• central dogma scientific principle explaining the flow of genetic information from DNA to RNA to protein
• central nervous system (CNS) portion of the nervous system made up of the brain and spinal cord
• central tolerance negative selection of self-reactive T cells in thymus
• centriole a component of a centrosome with the structural array of nine parallel microtubules arranged in triplets; involved in eukaryotic cell division
• centrosome a microtubule-organizing center for the mitotic spindle found in animal cells; it separates chromosomes during cell division and is composed of a pair of centrioles positioned at right angles to each other
• cephalosporins a group of cell wall synthesis inhibitors within the class of β-lactams
• cercarial dermatitis inflammation of the skin caused by a reaction to cercaria of Schistosoma spp., which can penetrate the skin and blood vessels; also called swimmer’s itch or clam digger’s itch
• cerebrospinal fluid (CSF) sterile liquid produced in the brain that fills the subarachnoid space of the brain and spinal column
• cervix the part of the uterus that connects to the vagina
• CFB group phylum consisting of the gram-negative, rod-shaped nonproteobacteria genera Cytophaga , Fusobacterium , and Bacteroides
• Chagas disease potentially fatal protozoan infection caused by Trypanosoma cruzi and endemic to Central and South America; transmitted by the triatomine bug (kissing bug)
• chancroid an STI caused by Haemophilus ducreyi that produces soft chancres on genitals
• charged tRNA activated tRNA molecule carrying its cognate amino acid
• chemical mediators chemicals or enzymes produced by a variety of cells; provide nonspecific antimicrobial defense mechanisms
• chemically defined media media in which all components are chemically defined
• chemiosmosis flow of hydrogen ions across the membrane through ATP synthase
• chemokines chemotactic cytokines that recruit specific subsets of leukocytes to infections, damaged tissue, and sites of inflammation
• chemotaxis directional movement of a cell in response to a chemical attractant
• chemotroph organism that gets its energy from the transfer of electrons originating from chemical compounds
• chickenpox common childhood disease caused by the varicella-zoster virus and marked by the formation of pustular lesions on the trunk
• chikungunya fever mosquito-borne viral disease caused by the chikungunya virus and characterized by high fever, joint pain, rash, and blisters
• chirality property of stereoisomer molecules by which their structures are nonsuperimposable mirror-images
• chitin polysaccharide that is an important component of fungal cell walls
• chlamydia a common STI caused by Chlamydia trachomatis
• chloramphenicol protein synthesis inhibitor with broad-spectrum activity that binds to the 50S subunit, inhibiting peptide bond formation
• chlorophyll a type of photosynthetic pigment found in some prokaryotic and eukaryotic cells
• chloroplast organelle found in plant and algal cells in which photosynthesis occurs
• cholera gastrointestinal illness caused by Vibrio cholera characterized by severe diarrhea
• chromatin combination of DNA with DNA binding proteins
• chromogenic substrate colorless substrate (chromogen) that is converted into a colored end product by the enzyme
• chromophores pigments that absorb and reflect particular wavelengths of light (giving them a color)
• chromosome discrete DNA structure within a cell that controls cellular activities
• chronic disease any disease that progresses and persists over a long time
• chronic granulomatous disease primary immunodeficiency caused by an impaired ability of phagocytic cells to kill ingested bacteria in the phagolysosome
• chronic wasting disease prion disease of deer and elk in the United States and Canada
• cilia (singular: cilium) short filamentous structures found on some eukaryotic cells; each is composed of microtubules in a 9+2 array, and may be used for locomotion, feeding, and/or movement of extracellular particles that come in contact with the cell
• ciliated epithelial cells hair-like cells in the respiratory tract that beat, pushing mucus secretions and trapped debris away from the sensitive tissues of the lungs
• ciliates protists with cilia (Ciliophora), including Paramecium and Stentor , classified within the Chromalveolata
• cisternae the sacs of the endoplasmic reticulum
• citric acid cycle see Krebs cycle
• class switching genetic rearrangement of constant region gene segments in plasma cells to switch antibody production from IgM to IgG, IgA, or IgE
• clindamycin semisynthetic protein synthesis inhibitor of the lincosamide class that binds to the 50S subunit, inhibiting peptide bond formation
• clone a genetically identical cell or individual
• Clostridium perfringens gastroenteritis relatively mild gastrointestinal illness caused by C. perfringens
• clusters of differentiation (CD) cell-surface glycoproteins that serve to identify and distinguish white blood cells
• coagulase enzyme that causes the activation of fibrinogen to form fibrin, promoting clotting of the blood
• coarse focusing knob a knob on a microscope that produces relatively large movements to adjust focus
• coccidioidomycosis disease caused by the highly infectious fungal pathogen Coccidioides immitis and related species
• codon three-nucleotide sequence within mRNA that specifies a particular amino acid to be incorporated into the polypeptide being synthesized
• coenocyte multinucleated eukaryotic cell that forms as a result of multiple rounds of nuclear division without the accompanying division of the plasma membrane
• coenocytic hyphae nonseptate hyphae that are multinucleate and lack cell walls or membranes between cells; characteristic of some fungi
• coenzyme organic molecule required for proper enzyme function that is not consumed and is reusable
• cofactor inorganic ion that helps stabilize enzyme conformation and function
• cognate amino acid amino acid added to a specific tRNA molecule that correctly corresponds to the tRNA’s anticodon and, hence, the mRNA’s codon, reflecting the genetic code
• cohort method a method used in observational studies in which a group of individuals is followed over time and factors potentially important in the development of disease are evaluated
• colistin membrane-active polymyxin that was historically used for bowel decontamination but now used for systemic infections with drug-resistant pathogens
• colitis inflammation of the large intestine
• collagenase enzyme that digests collagen, the dominant protein in connective tissue
• colony-forming unit (CFU) a counting quantity represented by a colony formed on solid medium from a single cell or a few cells
• commensalism type of symbiosis in which one population benefits and the other is not affected
• commercial sterilization type of sterilization protocol used in food production; uses conditions that are less harsh (lower temperatures) to preserve food quality but still effectively destroy vegetative cells and endospores of common foodborne pathogens such as Clostridium botulinum
• common cold most common cause of rhinitis in humans; associated with a variety of adenoviruses, coronaviruses, and rhinoviruses
• common source spread a mode of disease transmission in which every infection originates from the same source
• communicable able to be transmitted directly or indirectly from one person to another
• community group of interacting populations of organisms
• competitive inhibitor molecule that binds to an enzyme’s active site, preventing substrate binding
• competitive interactions interactions between populations in which one of them competes with another for resources
• complement activation cascading activation of the complement proteins in the blood, resulting in opsonization, inflammation, and lysis of pathogens
• complement fixation test test for antibodies against a specific pathogen using complement-mediated hemolysis
• complement system series of proteins that can become activated in the presence of invading microbes, resulting in opsonization, inflammation, and lysis of pathogens
• complementary base pairs base pairing due to hydrogen bonding that occurs between a specific purine and a specific pyrimidine; A bonds with T (in DNA), and C bonds with G
• complementary DNA (cDNA) a DNA molecule complementary to mRNA that is made through the activity of reverse transcriptase
• complex media media that contain extracts of animals and plants that are not chemically defined
• complex virus virus shape that often includes intricate characteristics not seen in the other categories of capsid
• compound microscope a microscope that uses multiple lenses to focus light from the specimen
• condenser lens a lens on a microscope that focuses light from the light source onto the specimen
• conditional mutation mutant form of a gene whose mutant phenotype is expressed only under certain environmental conditions
• confocal microscope a scanning laser microscope that uses fluorescent dyes and excitation lasers to create three-dimensional images
• conidia asexual fungal spores not enclosed in a sac; produced in a chain at the end of specialized hyphae called conidiophores
• conjugate vaccine a vaccine consisting of a polysaccharide antigen conjugated to a protein to enhance immune response to the polysaccharide; conjugate vaccines are important for young children who do not respond well to polysaccharide antigens
• conjugated protein protein carrying a nonpolypeptidic portion
• conjugation mechanism of horizontal gene transfer in bacteria in which DNA is directly transferred from one bacterial cell to another by a conjugation pilus
• conjugation pilus (sex pilus) hollow tube composed of protein encoded by the conjugation plasmid that brings two bacterial cells into contact with each other for the process of conjugation
• conjunctiva the mucous membranes covering the eyeball and inner eyelid
• conjunctivitis inflammation of the conjunctiva, the mucous membrane covering the eye and inside of the eyelid
• constitutively expressed describes genes that are transcribed and translated continuously to provide the cell with constant intermediate levels of the protein products
• contact dermatitis inflammation of the skin resulting from a type IV hypersensitivity to an allergen or irritant
• contact see exposure
• contact transmission movement of a pathogen between hosts due to contact between the two; may be direct or indirect
• contagious easily spread from person to person
• continuous cell line derived from transformed cells or tumors, these cells are often able to be subcultured many times, or, in the case of immortal cell lines, grown indefinitely
• continuous common source spread a mode of disease transmission in which every infection originates from the same source and that source produces infections for longer than one incubation period
• contractile vacuoles organelles found in some cells, especially in some protists, that take up water and then move the water out of the cell for osmoregulatory purposes (i.e., to maintain an appropriate salt and water balance)
• contrast visible differences between parts of a microscopic specimen
• convalescence stage the final stage of a whooping cough infection, marked by a chronic cough
• Coombs’ reagent antiserum containing antihuman immunoglobulins used to facilitate hemagglutination by cross-linking the human antibodies attached to red blood cells
• cooperative interactions interactions between populations in which both benefit
• cortex tightly packed layer of fungal filaments at the outer surface of a lichen; foliose lichens have a second cortex layer beneath the medulla
• counterstain a secondary stain that adds contrasting color to cells from which the primary stain has been washed out by a decolorizing agent
• crenation shriveling of a cell
• Creutzfeldt-Jakob disease form of transmissible spongiform encephalopathy found in humans; typically a fatal disease
• crisis phase point at which a fever breaks, reaching a peak before the hypothalamus resets back to normal body temperature
• critical item object that must be sterile because it will be used inside the body, often penetrating sterile tissues or the bloodstream
• cross-match in the major cross-match, donor red blood cells are checked for agglutination using recipient serum; in the minor cross-match, donor serum is checked for agglutinizing antibodies against recipient red blood cells
• cross-presentation a mechanism by which dendritic cells process antigens for MHC I presentation to CD8 T cells through phagocytosis of the pathogen (which would normally lead to MHC II presentation)
• cross-resistance when a single resistance mechanism confers resistance to multiple antimicrobial drugs
• cross-sectional study a type of observational study in which measurements are made on cases, both affected and unaffected, at one point in time and the measurements analyzed to uncover associations with the disease state
• crustose lichens lichens that are tightly attached to the substrate, giving them a crusty appearance
• cryptococcosis fungal pneumonia caused by the encapsulated yeast Cryptococcus neoformans commonly found in bird droppings
• cryptosporidiosis intestinal infection caused by Cryptosporidium parvum or C. hominis
• culture density the number of cells per volume of broth
• culture medium combination of compounds in solution that supports growth
• cutaneous mycosis any fungal infection that affects the surface of the skin, hair, or nails
• cyanobacteria phototrophic, chlorophyll-containing bacteria that produce large amounts of gaseous oxygen
• cyclic AMP (cAMP) intracellular signaling molecule made through the action of adenylyl cyclase from ATP when glucose levels are low, with the ability to bind to a catabolite activator protein to allow it to bind to regulatory regions and activate the transcription of operons encoding enzymes for metabolism of alternative substrates
• cyclic photophosphorylation pathway used in photosynthetic organisms when the cell’s need for ATP outweighs that for NADPH, thus bypassing NADPH production
• cyclosporiasis intestinal infection caused by Cyclospora cayetanensis
• cystic echinococcosis hydatid disease, an infection caused by the tapeworm Echinococcus granulosus that can cause cyst formation
• cysticerci larval form of a tapeworm
• cystitis inflammation of the bladder
• cysts microbial cells surrounded by a protective outer covering; some microbial cysts are formed to help the microbe survive harsh conditions, whereas others are a normal part of the life cycle
• cytochrome oxidase final ETS complex used in aerobic respiration that transfers energy-depleted electrons to oxygen to form H ₂ O
• cytokine storm an excessive release of cytokines, typically triggered by a superantigen, that results in unregulated activation of T cells
• cytokines protein molecules that act as a chemical signals; produced by cells in response to a stimulation event
• cytomegalovirus (CMV) infection human herpesvirus 5 infection that is typically asymptomatic but can become serious in immunocompromised patients, transplant recipients, and developing fetuses
• cytopathic effect cell abnormality resulting from a viral infection
• cytoplasm the gel-like material composed of water and dissolved or suspended chemicals contained within the plasma membrane of a cell
• cytoplasmic membrane see cell membrane
• cytoproct a protozoan cell structure that is specialized for excretion
• cytosine pyrimidine nitrogenous base found in nucleotides
• cytoskeleton a network of filaments or tubules in the eukaryotic cell that provides shape and structural support for cells; aids movement of materials throughout the cell
• cytostome a protozoan cell structure that is specialized for phagocytosis (i.e., to take in food)
• cytotoxic T cells effector cells of cellular immunity that target and eliminate cells infected with intracellular pathogens through induction of apoptosis
• cytotoxicity harmful effects to host cell