0.5 Glossary  (Page 18/18)

U

• UHT pasteurization method of pasteurization that exposes milk to ultra-high temperatures (near 140 °C) for a few seconds, effectively sterilizing it so that it can be sealed and stored for long periods without refrigeration
• ulcer open sore
• ultramicrotome a device that cuts thin sections for electron microscopy
• unit membrane biological membrane composed of two layers of phospholipid molecules with the nonpolar tails associating to form a hydrophobic barrier between the polar heads; also called lipid bilayer
• unsaturated fatty acid lipid with hydrocarbon chains containing one or more carbon-carbon double bonds and subsequently fewer than the maximum number of hydrogen atoms per chain
• uracil pyrimidine nitrogenous base found only in RNA nucleotides
• ureter duct that transports urine from the kidneys to the urinary bladder
• ureteritis inflammation of the ureter
• urethra duct through which urine passes from the urinary bladder to leave the body through the urinary meatus
• urethritis inflammation of the urethra
• urinary bladder an organ that stores urine until it is ready to be excreted
• urinary meatus the opening through which urine leaves the body
• use-dilution test a technique for determining the effectiveness of a chemical disinfectant on a surface; involves dipping a surface in a culture of the targeted microorganism, disinfecting the surface, and then transferring the surface to a fresh medium to see if bacteria will grow
• uterus female reproductive organ in which a fertilized egg implants and develops

V

• vaccination inoculation of a patient with attenuated pathogens or antigens to activate adaptive immunity and protect against infection
• vagina female reproductive organ that extends from the vulva to the cervix
• vaginitis inflammation of the vagina
• vaginosis an infection of the vagina caused by overgrowth of resident bacteria
• vancomycin cell wall synthesis inhibitor of the glycopeptide class
• vancomycin-intermediate Staphylococcus aureus (VISA) pathogen with intermediate vancomycin resistance due to increased targets for and trapping of vancomycin in the outer cell wall
• vancomycin-resistant enterococci (VRE) pathogens resistant to vancomycin through a target modification of peptidoglycan subunit peptides that inhibit binding by vancomycin
• vancomycin-resistant Staphylococcus aureus (VRSA) pathogen with resistance to vancomycin that has arisen as a result of the horizontal gene transfer of vancomycin resistance genes from VRE
• variolation the historical practice of inoculating a healthy patient with infectious material from a person infected with smallpox in order to promote immunity to the disease
• vas deferens pair of ducts in the male reproductive system that conduct sperm from the testes and seminal fluid to the ejaculatory duct
• vasculitis inflammation affecting blood vessels (either arteries or veins)
• VDRL (Venereal Disease Research Laboratory) test test for syphilis that detects anti-treponemal antibodies to the phospholipids produced due to the tissue destruction by Treponema pallidum ; antibodies are detected through a flocculation reaction with cardiolipin extracted from beef heart tissue
• vector animal (typically an arthropod) that transmits a pathogen from one host to another host; DNA molecules that carry DNA fragments from one organism to another
• vegetative cell a cell that is actively growing and dividing, and does not contain an endospore
• vehicle transmission transfer of a pathogen between hosts via contaminated food, water, or air
• vein blood vessel that returns blood from the tissues to the heart for recirculation
• vertical direct transmission transfer of a pathogen from mother to child during pregnancy, birth, or breastfeeding
• vertical gene transfer transfer of genes from parent to offspring
• viable cell live cell; live cells are usually detected as colony-forming units
• viable plate count direct method of measuring microbial growth in a culture; the number of viable or live cells is usually expressed in CFU/mL
• viral conjunctivitis inflammation of the conjunctiva caused by a viral infection
• viral envelope lipid membrane obtained from phospholipid membranes of the cell that surrounds the capsid
• viral hemagglutination inhibition assay assay used to quantify the amount of neutralizing antibody against a virus by showing a decrease in hemagglutination caused by a standardized amount of virus
• viral titer number of virions per unit volume
• viremia presence of virus in blood
• viricide chemical or physical treatment that destroys or inactivates viruses
• virion inert particle that is the reproductive form of a virus
• viroid infectious plant pathogen composed of RNA
• virology the study of viruses
• virulence degree to which an organism is pathogenic; severity of disease signs and symptoms
• virulence factor product of a pathogen that assists in its ability to cause infection and disease
• virulent phage bacteriophage for which infection leads to the death of the host cell; a phage that undergoes the lytic cycle
• virus an acellular microorganism, consisting of proteins and genetic material (DNA or RNA), that can replicate itself by infecting a host cell
• virusoid small piece of RNA associated with larger RNA of some infectious plant viruses
• volutin inclusions of polymerized inorganic phosphate; also called metachromatic granules
• vulva the female external genitalia

W

• water activity water content of foods or other materials
• wavelength the distance between one peak of a wave and the next peak
• Weil’s disease advanced stage of leptospirosis in which the kidney and liver become seriously infected
• West African trypanosomiasis chronic form of African trypanosomiasis caused by Trypanosoma brucei gambiense
• West Nile encephalitis mosquito-borne disease caused by the West Nile virus (WNV) that can result in swelling of the brain and death in severe cases
• western blot technique used to detect the presence of a certain protein within a given protein sample in which proteins within the sample are separated by PAGE, immobilized on a membrane, and then exposed first to an antibody that binds to the protein of interest and then second to an antibody equipped with a molecular beacon that will bind to the first antibody
• western equine encephalitis serious but rare mosquito-borne viral infection of the brain that is found primarily in the central and western United States
• wet mount a slide preparation technique in which a specimen is placed on the slide in a drop of liquid
• wheal-flare reaction localized type I hypersensitivity reaction, involving a raised, itchy bump (wheal) and redness (flare), to injected allergen
• whooping cough common name for pertussis
• wild type phenotype of an organism that is most commonly observed in nature
• Winterbottom’s sign acute swelling of lymph nodes at the back of the neck that is an early sign of African trypanosomiasis
• wobble position third position of a codon that, when changed, typically results in the incorporation of the same amino acid because of the degeneracy of the genetic code
• World Health Organization (WHO) international public health organization within the United Nations; monitors and communicates international public health information and coordinates international public health programs and emergency interventions

X

• xenobiotic compound synthesized by humans and introduced to an environment in much higher concentrations than expected in nature
• xenograft transplanted tissue from a donor that is of a different species than the recipient
• X-linked agammaglobulinemia genetic disorder resulting in an inability to produce antibodies
• x-y mechanical stage knobs knobs on a microscope that are used to adjust the position of the specimen on the stage surface, generally to center it directly above the light

Y

• yeast any unicellular fungus
• yeast infection fungal infection of the vagina typically caused by an overgrowth of resident Candida spp.
• yellow fever mild to potentially fatal mosquito-borne viral disease caused by the yellow fever virus

Z

• Ziehl-Neelsen technique a method of acid-fast staining that uses heat to infuse the primary stain, carbolfuchsin, into acid-fast cells
• zone of inhibition clear zone around a filter disk impregnated with an antimicrobial drug, indicating growth inhibition due to the antimicrobial drug
• zoonosis see zoonotic disease
• zoonotic disease any disease that is transmitted to humans by animals
• zooplankton heterotrophic plankton
• Z-scheme electron flow seen in noncyclic photophosphorylation in plants, algae, and cyanobacteria due to the use of both PSI and PSII
• zygospores spores used by Zygomycetes for sexual reproduction; they have hard walls formed from the fusion of reproductive cells from two individuals