121 terms

Microbiology Glossary Terms - G, H MSUTIB

G, H Terms
A structure that contains gametes or in which gametes are formed.
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One of the five subgroups of proteobacteria, each with distinctive 16S rRNA sequences. This is the largest subgroup and is very diverse physiologically; many important genera are facultatively anaerobic chemoorganotrophs.
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gas gangrene
A type of gangrene that arises from dirty, lacerated wounds infected by anaerobic bacteria, especially species of Clostridium. As the bacteria grow, they release toxins and ferment carbohydrates to produce carbon dioxide and hydrogen gas.
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Inflammation of the stomach.
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An acute inflammation of the lining of the stomach and intestines, characterized by anorexia, nausea, diarrhea, abdominal pain, and weakness. It has various causes including food poisoning due to such organisms as E. coli, S. aureus, Campylobacter (campylobacteriosis), and Salmonella species; consumption of irritating food or drink; or psychological factors such as anger, stress, and fear. Also called enterogastritis.
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gas vacuole
A gas-filled vacuole found in cyanobacteria and some other aquatic bacteria that provides flotation. It is composed of gas vesicles, which are made of protein.
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A DNA segment or sequence that codes for a polypeptide, rRNA, or tRNA.
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gene gun
A device that uses high-pressure gas or another propellant to shoot a spray of DNA-coated microprojectiles into cells and transform them. Sometimes it is called a biolistic device.
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generalized transduction
The transfer of any part of a bacterial genome when the DNA fragment is packaged within a phage capsid by mistake.
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general recombination
Recombination involving a reciprocal exchange of a pair of homologous DNA sequences; it can occur any place on the chromosome.
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generation time
The time required for a microbial population to double in number.
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genetic engineering
The deliberate modification of an organism's genetic information by directly changing its nucleic acid genome.
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genital herpes
A sexually transmitted disease caused by the herpes simplex virus type 2.
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genital ulcer disease
See chancroid.
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A sexually transmitted disease caused by the gram-negative bacterium Haemophilus ducreyi. Worldwide, chancroid is an important cofactor in the transmission of the AIDS virus. Also known as genital ulcer disease due to the painful circumscribed ulcers that form on the penis or entrance to the vagina.
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The full set of genes present in a cell or virus; all the genetic material in an organism; a haploid set of genes in a cell.
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The study of the molecular organization of genomes, their information content, and the gene products they encode.
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A well-defined group of one or more species that is clearly separate from other genera.
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geographic information system (GIS)
A data management system that organizes and displays digital map data from remote sensing and aids in the analysis of relationships between mapped features.
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German measles
See rubella.
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A moderately contagious skin disease that occurs primarily in children 5 to 9 years of age that is caused by the rubella virus, which is acquired by droplet inhalation into the respiratory system; German measles.
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An agent that kills pathogens and many nonpathogens but not necessarily bacterial endospores.
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The stage following bacterial endospore activation in which the endospore breaks its dormant state. Germination is followed by outgrowth.
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Ghon complex (gon)
The initial focus of parenchymal infection in primary pulmonary tuberculosis.
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A common intestinal disease caused by the parasitic protozoan Giardia lamblia.
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Inflammation of the gingival tissue.
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Inflammation of the gingiva and other oral mucous membranes.
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gliding motility
A type of motility in which a microbial cell glides along when in contact with a solid surface.
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global regulatory systems
Regulatory systems that simultaneously affect many genes and pathways.
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An inflammatory disease of the renal glomeruli.
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Polysaccharides composed of glucose units held together by glycosidic linkages. Some types of glucans have a(1_3) and a(1_6) linkages and bind bacterial cells together on teeth forming a plaque ecosystem.
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The synthesis of glucose from noncarbohydrate precursors such as lactate and amino acids.
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A network of polysaccharides extending from the surface of bacteria and other cells.
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A highly branched polysaccharide containing glucose, which is used to store carbon and energy.
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The anaerobic conversion of glucose to lactic acid by use of the Embden-Meyerhof pathway.
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glycolytic pathway
See Embden-Meyerhof pathway.
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A pathway that degrades glucose to pyruvate; the six-carbon stage converts glucose to fructose 1,6-bisphosphate, and the three-carbon stage produces ATP while changing glyceraldehyde 3-phosphate to pyruvate.
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glyoxylate cycle
A modified tricarboxylic acid cycle in which the decarboxylation reactions are bypassed by the enzymes isocitrate lyase and malate synthase; it is used to convert acetyl-CoA to succinate and other metabolites.
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Animals that are germfree (microorganism free) or live in association with one or more known microorganisms.
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Golgi apparatus
A membranous eucaryotic organelle composed of stacks of flattened sacs (cisternae), which is involved in packaging and modifying materials for secretion and many other processes.
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Bacteria of the species Neisseria gonorrhoeae-the organism causing gonorrhea.
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An acute infectious sexually transmitted disease of the mucous membranes of the genitourinary tract, eye, rectum, and throat. It is caused by Neisseria gonorrhoeae.
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graft-versus-host disease
A disease that results when mature post-thymic T cells in donor grafts (e.g., bone marrow) recognize the host as foreign and attack it.
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Gram stain
A differential staining procedure that divides bacteria into gram-positive and gram-negative groups based on their ability to retain crystal violet when decolorized with an organic solvent such as ethanol.
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A stack of thylakoids in the chloroplast stroma.
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Term applied to nodular inflammatory lesions containing phagocytic cells.
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greenhouse gases
Gases released from the earth's surface through chemical and biological processes that interact with the chemicals in the stratosphere to decrease the release of radiation from the earth. It is believed that this leads to global warming.
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An antibiotic from Penicillium griseofulvum given orally to treat chronic dermatophytic infections of skin and nails.
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group translocation
A transport process in which a molecule is moved across a membrane by carrier proteins while being chemically altered at the same time.
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An increase in cellular constituents.
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growth factors
Organic compounds that must be supplied in the diet for growth because they are essential cell components or precursors of such components and cannot be synthesized by the organism.
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A purine derivative, 2-amino-6-oxypurine, found in nucleosides, nucleotides, and nucleic acids.
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Guillain-Barr syndrome
A relatively rare disease affecting the peripheral nervous system, especially the spinal nerves, but also the cranial nerves. The cause is unknown, but it most often occurs after an influenza infection or flu vaccination. Also called French Polio.
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A soft, gummy tumor occurring in tertiary syphilis.
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gut-associated lymphoid tissue (GALT)
The defensive lymphoid tissue present in the intestines. See Peyer's patches.
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H-2 complex
Term for the MHC in the mouse.
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halobacteria or extreme halophiles
A group of archaea that have an absolute dependence on high NaCl concentrations for growth and will not survive at a concentration below about 1.5 M NaCl.
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A microorganism that requires high levels of sodium chloride for growth.
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Hansen's disease
See leprosy.
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A severe disfiguring skin disease caused by Mycobacterium leprae.
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hantavirus pulmonary syndrome
The disease in humans caused by the pulmonary syndrome hantavirus. Deer mice shed the virus in their feces, humans inhale the virus and first develop ordinary flulike aches and pains. Within a few days the hantavirus causes lung damage and capillary leakage. After about a week the infected person enters a crisis phase and may die.
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A molecule not immunogenic by itself but that, when coupled to a macromolecular carrier, can elicit antibodies directed against itself.
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harborage transmission
The mode of transmission in which an infectious organism does not undergo morphological or physiological changes within the vector.
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hay fever
Allergic rhinitis; a type of atopic allergy involving the upper respiratory tract.
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A state of optimal physical, mental, and social well-being, and not merely the absence of disease and infirmity.
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healthy carrier
An individual who harbors a pathogen, but is not ill.
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heat-shock proteins
Proteins produced when cells are exposed to high temperatures or other stressful conditions. They protect the cells from damage and often aid in the proper folding of proteins.
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In virology this refers to a virus with a helical capsid surrounding its nucleic acid.
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Enzymes that use ATP energy to unwind DNA ahead of the replication fork.
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The adherence of red blood cells to the surface of something, such as another cell or a virus.
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The agglutination of red blood cells by antibodies.
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The antibody responsible for a hemagglutination reaction.
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A flagellated protozoan parasite that is found in the bloodstream.
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A substance that causes hemolysis (the lysis of red blood cells). At least some hemolysins are enzymes that destroy the phospholipids in erythrocyte plasma membranes.
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The disruption of red blood cells and release of their hemoglobin. There are several types of hemolysis when bacteria such as streptococci and staphylococci grow on blood agar. In a-hemolysis, a narrow greenish zone of incomplete hemolysis forms around the colony. A clear zone of complete hemolysis without any obvious color change is formed during b-hemolysis.
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hemolytic uremic syndrome
A kidney disease characterized by blood in the urine and often by kidney failure. It is caused by enterohemorrhagic strains of Escherichia coli O157:H7 that produce a Shiga-like toxin, which attacks the kidneys.
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hemorrhagic fever
A fever usually caused by a specific virus that may lead to hemorrhage, shock, and sometimes death.
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Any infection that results in inflammation of the liver. Also refers to liver inflammation as such.
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hepatitis A
A type of hepatitis that is transmitted by fecal-oral contamination; it primarily affects children and young adults, especially in environments where there is poor sanitation and overcrowding. It is caused by the hepatitis A virus, a single-stranded RNA virus.
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hepatitis B
This form of hepatitis is caused by a double-stranded DNA virus (HBV) formerly called the "Dane particle." The virus is transmitted by body fluids.
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hepatitis C
About 90% of all cases of viral hepatitis can be traced to either HAV or HBV. The remaining 10% is believed to be caused by one and possibly several other types of viruses. At least one of these is hepatitis C (formerly non-A, non-B).
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hepatitis D
The liver diseases caused by the hepatitis D virus in those individuals already infected with the hepatitis B virus.
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hepatitis E
The liver disease caused by the hepatitis E virus. Usually, a subclinical, acute infection results; however, there is a high mortality in women in their last trimester of pregnancy.
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herd immunity
The resistance of a population to infection and spread of an infectious organism due to the immunity of a high percentage of the population.
herpes labialis
See cold sore.
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A lesion caused by the herpes simplex virus; usually occurs on the border of the lips or nares. Also known as a fever blister or herpes labialis.
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herpetic keratitis
An inflammation of the cornea and conjunctiva of the eye resulting from a herpes simplex virus infection.
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Specialized cells produced by cyanobacteria that are the sites of nitrogen fixation.
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heteroduplex DNA
A double-stranded stretch of DNA formed by two slightly different strands that are not completely complementary.
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heterogeneous nuclear RNA (hnRNA)
The RNA transcript of DNA made by RNA polymerase II; it is then processed to form mRNA.
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heterolactic fermenters
Microorganisms that ferment sugars to form lactate, and also other products such as ethanol and CO2.
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An organism that uses reduced, preformed organic molecules as its principal carbon source.
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heterotrophic nitrification
Nitrification carried out by chemoheterotrophic microorganisms.
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hexon or hexamer
A capsomer composed of six protomers.
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hexose monophosphate pathway
See pentose phosphate pathway.
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The pathway that oxidizes glucose 6-phosphate to ribulose 5-phosphate and then converts it to a variety of three to seven carbon sugars; it forms several important products (NADPH for biosynthesis, pentoses, and other sugars) and also can be used to degrade glucose to CO2.
(See page(s) 177, A-14)
Hfr strain
A bacterial strain that donates its genes with high frequency to a recipient cell during conjugation because the F factor is integrated into the bacterial chromosome.
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high-energy molecule
A molecule whose hydrolysis under standard conditions makes available a large amount of free energy (the standard free energy change is more negative than about 27 kcal/mole); a high-energy molecule readily decomposes and transfers groups such as phosphate to acceptors.
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high oxygen diffusion environment
A microbial environment in close contact with air and through which oxygen can move at a rapid rate (in comparison with the slow diffusion rate of oxygen through water).
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A small basic protein with large amounts of lysine and arginine that is associated with eucaryotic DNA in chromatin.
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A systemic fungal infection caused by Histoplasma capsulatum var capsulatum.
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An eruption of the skin.
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A structure produced by some bacteria and algae that attaches the cell to a solid object.
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A complete enzyme consisting of the apoenzyme plus a cofactor.
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holozoic nutrition
In this type of nutrition, nutrients (such as bacteria) are acquired by phagocytosis and the subsequent formation of a food vacuole or phagosome.
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homolactic fermenters
Organisms that ferment sugars almost completely to lactic acid.
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horizontal gene transfer
The process in which genes are transferred from one mature, independent organism to another.
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Small motile fragments produced by fragmentation of filamentous cyanobacteria; used for asexual reproduction and dispersal.
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The body of an organism that harbors another organism. It can be viewed as a microenvironment that shelters and supports the growth and multiplication of a parasitic organism.
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host restriction
The degradation of foreign genetic material by nucleases after the genetic material enters a host cell.
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human herpesvirus 6 (HHV-6, type A and B)
HHV-6 was discovered in 1986 and was initially called the human B-lymphotropic virus. The virus was later shown to have a marked tropism for CD41 T cells and was renamed HHV-6. HHV-6 is genetically similar to cytomegalovirus. HHV-6 causes exanthem subitum (roseola infantum or sixth disease) in infants and has been suspected of involvement in many conditions, including opportunistic infections in immunocompromised patients, hepatitis, lymphoproliferative diseases, synergistic interactions with HIV, lymphadenitis, and chronic fatigue syndrome.
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human immunodeficiency virus (HIV)
A lentivirus of the family Retroviridae that is associated with the onset of AIDS.
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human leukocyte antigen complex (HLA)
An antigen on the surface of cells of human tissues and organs that is recognized by the immune system cells and therefore is important in graft rejection and regulation of the immune response. This is the same as MHC class II.
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humoral (antibody-mediated) immunity
The type of immunity that results from the presence of soluble antibodies in blood and lymph; also known as antibody-mediated immunity.
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A fast-growing cell line produced by fusing a cancer cell (myeloma) to another cell, such as an antibody-producing cell.
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A microbodylike organelle that contains a unique electron transfer pathway in which hydrogenase transfers electrons to protons (which act as the terminal electron acceptors) and molecular hydrogen is formed.
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A polar substance that has a strong affinity for water (or is readily soluble in water).
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A nonpolar substance lacking affinity for water (or which is not readily soluble in water).
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hyperendemic disease
A disease that has a gradual increase in occurrence beyond the endemic level, but not at the epidemic level, in a given population; also may refer to a disease that is equally endemic in all age groups.
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A rapid production of multiple mutations in a gene or genes through the activation of special mutator genes. The process may be deliberately used to maximize the possibility of creating desirable mutants.
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A condition of increased immune sensitivity in which the body reacts to an antigen with an exaggerated immune response that usually harms the individual. Also termed an allergy.
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A bacterium that has its growth optimum between 80 degrees C and about 113 degrees C. Hyperthermophiles usually do not grow well below 55 degrees C.
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hypha (hi_fah; pl., hyphae) The unit of structure of most fungi and some bacteria; a tubular filament.
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Deficiency of iron in the blood.
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The smaller half of a diatom frustule.
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A tentative assumption or educated guess developed to explain a set of observations.
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Having a low oxygen level.
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