0.5 Glossary  (Page 16/18)

S

• σ factor subunit of bacterial RNA polymerase conferring promoter specificity that can be substituted with a different version in response to an environmental condition, allowing for a quick and global change of the regulon transcribed
• saccharide carbohydrate
• salmonellosis gastrointestinal illness caused by Salmonella bacteria
• salpingitis inflammation of the fallopian tubes
• sandwich ELISA EIA in which the primary antibody is first attached to the wells of a microtiter plate, allowing it to capture antigen from an unknown solution to be quantified
• Sanger DNA sequencing (dideoxy method, chain termination method) the original DNA sequencing technique in which dideoxy nucleotides, each labeled with a molecular beacon, are used to terminate chain elongation; the resulting incrementally sized fragments are then separated by electrophoresis to determine the sequence of the DNA molecule
• sanitization protocol that reduces microbial load on inanimate surfaces to levels deemed safe for public health
• saprozoic refers to protozoans that ingest small, soluble food molecules
• SARS severe acute respiratory syndrome; caused by a zoonotic coronavirus that results in flu-like symptoms
• saturated fatty acid lipid with hydrocarbon chains containing only single bonds, which results in the maximum number of hydrogen atoms per chain
• scanning electron microscope (SEM) a type of electron microscope that bounces electrons off of the specimen, forming an image of the surface
• scanning probe microscope a microscope that uses a probe that travels across the surface of a specimen at a constant distance while the current, which is sensitive to the size of the gap, is measured
• scanning tunneling microscope a microscope that uses a probe that is passed just above the specimen as a constant voltage bias creates the potential for an electric current between the probe and the specimen
• scarlet fever bacterial infection caused by Streptococcus pyogenes , marked by a high fever and a disseminated scarlet rash
• schistosomiasis helminthic infection caused by Schistosoma spp.; transmitted from a snail intermediate host to human swimmers or bathers in freshwater
• schizogony asexual reproduction in protozoans that is characterized by multiple cell divisions (one cell dividing to form many smaller cells)
• scolex the head region of a cestode (tapeworm), which typically has suckers and/or hooks for attachment to the host
• scrapie form of transmissible spongiform encephalopathy that primarily affects sheep
• sebaceous gland a gland located in hair follicles that secretes sebum
• sebum lipid-rich substance secreted by the sebaceous glands of the skin
• secondary antibody antibody to which an enzyme is attached for use in ELISA assays; in direct and sandwich ELISAs, it is specific for the antigen being quantified, whereas in indirect ELISA, it is specific for the primary antibody
• secondary immunodeficiency impaired immune response due to infection, metabolic disturbance, poor diet, stress, or other acquired factors
• secondary infection second infection that develops after a primary infection as a result of the primary disease compromising immune defenses or antibiotics, thus eliminating protective microbiota
• secondary lymphoid tissue one of two types of lymphatic tissue; comprises the spleen, lymph nodes, Peyer’s patches, and mucosa associated lymphoid tissue (MALT)
• secondary response the adaptive immune response produced in response to a specific antigen to which the body has previously been exposed
• secondary structure structure stabilized by hydrogen bonds between the carbonyl and amine groups of a polypeptide chain; may be an α-helix or a β-pleated sheet, or both
• secretory vesicle membranous sac that carries molecules through the plasma membrane to be released (secreted) from the cell
• selective IgA deficiency primary immunodeficiency in which individuals produce normal levels of IgG and IgM, but are unable to produce secretory IgA
• selective media media that contain additives that encourage the growth of some bacteria while inhibiting others
• selective toxicity desirable quality of an antimicrobial drug indicating that it preferentially kills or inhibits the growth of the target microbe while causing minimal or no harm to the host
• semiconservative DNA replication pattern of DNA replication process whereby each of the two parental DNA strands acts as a template for new DNA to be synthesized, producing hybrid old- and new-strand daughter molecules
• semicritical item object that contacts mucous membranes or nonintact skin but does not penetrate tissues; requires a high level of disinfection
• seminal vesicles glands that contribute fluid to semen
• semisynthetic antimicrobial chemically modified derivative of a natural antibiotic
• sense strand strand of DNA that is not transcribed for gene expression; it is complementary to the antisense strand
• sepsis systemic inflammatory response to an infection that results in high fever and edema, causing organ damage and possibly leading to shock and death
• septate hyphae hyphae that contain walls between individual cells; characteristic of some fungi
• septic arthritis see infectious arthritis
• septic shock serious condition marked by the loss of blood pressure resulting from an inflammatory response against a systemic infection
• septic the condition of being septicemic; having an infection in the blood
• septicemia condition in which pathogens are multiplying in blood
• septicemic plague form of plague that occurs when the bacterial pathogen gains access to the bloodstream
• septum separating structure that forms during cell division; also describes the separating wall between cells in a filament
• sequela (plural: sequelae) condition that arises as a consequence of a prior disease
• serial dilution sequential transfer of known volumes of culture samples from one tube to another to perform a several-fold dilution of the original culture
• seroconversion point in an infection at which antibody to a pathogen is detectible using an immunoassay
• serotype strain or variation of the same species of bacteria; also called serovar
• serovar specific strain of bacteria identified by agglutination using strain-specific antisera
• serum fluid portion of the blood after clotting has occurred; generally lacks clotting factors
• serum sickness systemic type III hypersensitivity reaction
• sessile attached to a surface
• severe combined immunodeficiency disease (SCID) genetic disorder resulting in impaired function of B cells and T cells
• sex pilus specialized type of pilus that aids in DNA transfer between some prokaryotic cells
• sheath part of the tail on a bacteriophage that contracts to introduce the viral DNA into the bacterium
• shigellosis gastrointestinal illness caused by Shigella bacteria, also called bacillary dysentery
• shingles acute and painful rash that forms following the reactivation of a latent chickenpox infection
• shock extreme drop in blood pressure that, among other causes, can result from a strong immune response to the activity of toxins or response to bacterial products and can result in death
• shuttle vector a plasmid that can move between bacterial and eukaryotic cells
• side chain the variable functional group, R , attached to the α carbon of an amino acid
• sign objective and measurable indication of a disease
• silent mutation point mutation that results in the same amino acid being incorporated into the resulting polypeptide
• simple microscope a type of microscope with only one lens to focus light from the specimen
• simple staining a staining technique that uses a single dye
• single-stranded binding protein protein that coats the single strands of DNA near each replication fork to prevent the single-stranded DNA from rewinding into a double helix
• sinusitis inflammation of the sinuses
• S-layer cell envelope layer composed of protein covering the cell walls of some bacteria and archaea; in some archaea, may function as the cell wall
• slime layer a type of glycocalyx with unorganized layers of polysaccharides that aid bacterial adherence to surfaces
• smear a thin layer of a specimen on a slide
• smooth endoplasmic reticulum a type of endoplasmic reticulum that lacks ribosomes, is involved in the biosynthesis of lipids and in carbohydrate metabolism, and serves as the site of detoxification of toxic compounds within the cell
• soft chancres soft, painful ulcers associated with the STI chancroid
• soma cell body of a neuron
• sonication method of microbial control that involves application of ultrasound waves to form cavitation within a solution, including inside cells, disrupting cell components as a result
• Southern blot a technique in molecular genetics used to detect the presence of certain DNA sequences within a given DNA sample; DNA fragments within the sample are separated by agarose gel electrophoresis, immobilized on a membrane, and then exposed to a specific DNA probe labeled with a radioactive or fluorescent molecular beacon to aid in detection
• specialized transduction transfer of a specific piece of bacterial chromosomal DNA near the site of integration by the phage
• specificity the ability of the specific adaptive immune system to target specific pathogens or toxins
• spike viral glycoprotein embedded within the viral capsid or envelope used for attachment to host cells
• spirochetes a group of long, thin, spiral-shaped fastidious bacteria that includes the human pathogens that cause syphilis, Lyme disease, and leptospirosis
• spleen abdominal organ consisting of secondary lymphoid tissue that filters blood and captures pathogens and antigens that pass into it; also contains specialized macrophages and dendritic cells that are crucial for antigen presentation
• spliceosome protein complex containing small nuclear ribonucleoproteins that catalyzes the splicing out of intron-encoded RNA sequences from the primary transcript during RNA maturation in eukaryotes
• spontaneous generation the now-disproven theory that life can arise from nonliving matter
• spontaneous mutation mutation not caused by a mutagen that occurs through DNA replication errors
• sporadic disease an illness that occurs at relatively low levels with no discernible pattern or trend, frequently with no geographic focus
• spores specialized cells that may be used for reproduction or may be specialized to withstand harsh conditions
• sporotrichosis subcutaneous infection caused by the fungus Sporothrix schenkii , which causes skin lesions and can potentially spread to the lymphatic system; also known as rose gardener’s disease or rose thorn disease
• sporulation the process by which a vegetative cell produces a dormant endospore
• spread plate method a technique used for inoculating plates with diluted bacterial samples for the purpose of cell counting; the liquid sample is pipetted onto solid medium and spread uniformly across the plate
• St. Louis encephalitis mosquito-borne viral infection of the brain that occurs primarily in the central and southern United States
• stage the platform of a microscope on which slides are placed
• staining the addition of stains or dyes to a microscopic specimen for the purpose of enhancing contrast
• staphylococcal food poisoning gastrointestinal illness caused by toxins produced by Staphylococcus aureus
• staphylolysins a class of staphylococcal exotoxins that are cytotoxic to skin cells and white blood cells
• starch energy-storage polysaccharide in plants; composed of two types of glucose polymers: amylose and amylopectin
• start codon AUG codon, specifying methionine, which is typically the codon that initiates translation
• stationary phase interval during which the number of cells formed by cell division is equal to the number of cells dying
• stereoisomers isomers that differ in the spatial arrangements of atoms
• sterilant strong chemical that effectively kills all microbes and viruses in or on an inanimate item
• sterile field specified area that is free of all vegetative microbes, endospores, and viruses
• sterilization protocol that completely removes all vegetative cells, endospores, and viruses from an item
• steroid lipid with complex, ringed structures found in cell membranes and hormones
• sterol the most common type of steroid; contains an OH group at one specific position on one of the molecule’s carbon rings
• sticky ends short, single-stranded complementary overhangs that may be produced when many restriction enzymes cut DNA
• stigma light-sensing eyespot found in Euglena
• stop codon (nonsense codon) one of three codons for which there is no tRNA with a complementary anticodon; a signal within the mRNA for termination of translation
• stratum corneum a layer of dead, keratinized cells that forms the uppermost layer of the epidermis
• strep throat (streptococcal pharyngitis) bacterial pharyngitis caused by Streptococcus pyogenes
• streptococcal toxic shock-like syndrome (STSS) condition similar to staphylococcal toxic shock syndrome but with greater likelihood of bacteremia, necrotizing fasciitis, and acute respiratory distress syndrome
• stroma a gel-like fluid that makes up much of a chloroplast’s volume, and in which the thylakoids floats
• strongyloidiasis soil-transmitted intestinal infection caused by the helminth Strongyloides stercoralis
• structural formula graphic representation of the molecular structure showing how the atoms are arranged
• structural isomers molecules composed of the same numbers and types of atoms but with different bonding sequences
• subacute bacterial endocarditis form of endocarditis in which damage to the valves of the heart occurs over months as a result of blood clot formation and immune-response-induced fibrosis of the valves
• subclinical disease disease that does not present any signs or symptoms
• subcutaneous mycosis any fungal infection that penetrates the epidermis and dermis to enter deeper tissues
• substrate chemical reactants of an enzymatic reaction
• substrate-level phosphorylation direct method of ATP production in which a high-energy phosphate group is removed from an organic molecule and added to an ADP molecule
• subunit vaccine vaccine that contains only key antigens as opposed to whole pathogens
• sugar-phosphate backbone alternating sugar-phosphate structure composing the framework of a nucleic acid strand that results from phosphodiester bond formation between nucleotides
• sulfonamides (sulfa drugs) group of structurally related synthetic antimicrobial compounds that function as antimetabolites, competitively inhibiting an enzyme in the bacterial folic acid synthesis pathway
• superantigen class of exotoxin that triggers a strong nonspecific immune response with excessive production of cytokines (cytokine storm) causing inflammation, high fever, shock, and, potentially, death
• supercoiled extensive wrapping and twisting of a DNA molecule, allowing the DNA to fit within a small space
• supercoiling process in which DNA is underwound or overwound to fit inside a cell
• supercritical fluid molecule, commonly carbon dioxide, brought to high pressures to reach a state that has physical properties between those of liquids and gases, allowing it to effectively penetrate surfaces and cells to form carbonic acid, which lowers the pH of cells considerably, leading to sterilization
• superinfection secondary infection that may develop as a result of long-term, broad-spectrum antimicrobial use
• superoxide dismutase enzyme that catalyzes the breakdown of superoxide anions
• suppurative producing pus; purulent
• surfactant group of chemical compounds used for degerming; lower the surface tension of water, creating emulsions that mechanically carry away microorganisms
• sweat gland one of numerous tubular glands embedded in the dermis that secretes the watery substance known as perspiration
• symbiosis any interaction between different species within a community
• symptom subjective experience of disease felt by the patient
• synapse junction between a neuron and another cell
• syncytia multinucleated cells that form from the fusion of normal cells during infections or other processes
• syndrome group of signs and symptoms characteristic of a particular disease
• syngamy process in which haploid gametes fuse
• synthetic antimicrobial antimicrobial developed from a chemical not found in nature
• syphilis an STI caused by the bacterium Treponema pallidum
• systemic autoimmune disease autoimmune disease that affect the organism as a whole, rather than a single organ
• systemic infection infection that has spread to multiple locations or body systems
• systemic inflammatory response syndrome (SIRS) severe inflammatory response to the presence of microbes in the blood; can lead to sepsis
• systemic lupus erythematosus (SLE) systemic autoimmune disease producing inflammatory type III hypersensitivities as antibodies form immune complexes with nuclear and cytoplasmic antigens
• systemic mycosis a fungal infection that spreads throughout the body