Biotechnology and Genetics terms starting with S

345 terms

SOS response The synthesis of a whole set of DNA repair, recombination and replication proteins in bacteria suffering severe DNA damage (e.g.
source DNA The DNA from an organism that contains a target gene, and used as the starting material in a cloning experiment.
source organism A bacterium, plant or animal from which DNA is purified and used in a cloning experiment.
Southern blot A nitrocellulose or nylon membrane to which DNA fragments previously separated by gel electrophoresis, have been transferred by capillary action.
Southern blotting See Southern hybridization.
Southern hybridization A procedure in which a cloned, labelled segment of DNA is hybridized to DNA restriction fragments on a Southern blot.
Southern hybridization (Southern blotting) A procedure in which DNA restriction fragments are transferred from an agarose gel to a nitrocellulose filter, where the denatured DNA is then hybridized…
spacer sequence A DNA sequence separating neighbouring genes; spacer sequences are not usually transcribed.
SPAR Abbreviation for single primer amplification reaction.
sparger A device that introduces, into a bioreactor, air in the form of fine bubbles.
spatial autocorrelation statistics A set of statistical parameters aimed to depict the spatial (geographical) pattern of genetic diversity in a population.
speciation The evolutionary differentiation of a pre-existing species into one or more distinct species.
Species Organisms in the same genus that have similar characteristics.
specific combining ability (Abbreviation: SCA). A component of genetic variance calculable where a number of genotypes are intercrossed in all possible combinations.
specificity When referring to a medical test, specificity refers to the percentage of people who test negative for a specific disease among a group of people who do…
Spectral karyotype (SKY) A visualization of all of an organism's chromosomes together, each labeled with a different color.
spent medium After sub-culture, medium which is discarded because it has been depleted of nutrients, dehydrated, or accumulated toxic metabolic products.
sperm Abbreviation for spermatozoon.
sperm competition Competition between different spermatozoa to fertilize the of a single female.
sperm sexing The separation of mammalian sperm into those bearing an X chromosome and those bearing a Y chromosome, in order to be able to produce, via artificial…
spermatid Immature spermatozoon. One of the four cells formed at the end of the second meiotic division in spermatogenesis.
spermatocyte The premeiotic parental cell of the spermatids; the primary spermatocyte before the initiation of the first meiotic division; the secondary spermatocyte…
spermatogenesis The series of cell divisions in the testis as a result of which the formation and the maturation of the male gametes (i.e. sperm) are achieved.
spermatogonium (pl.: spermatogonia) Primordial male germ cell. These can either divide by mitosis to produce daughter cells, or enter a growth phase and differentiate…
spermatozoon (Abbreviation: sperm). (pl.: spermatozoa) The mature, mobile gametic cell of male animals, produced in the testis.
spharoblast Nodule of wood which can give rise to adventitious shoots with juvenile characteristics.
spheroplast (AlteRNA tive spelling: sphaeroplast). A microbial or plant cell from which most of the cell wall has been removed, usually by enzymatic treatment.
spike 1. An inflorescence in which the main axis is elongated and the flowers are sessile. 2.
spikelet The unit of inflorescence in grasses, made up of a small group of florets.
spindle An intracellular fibrous structure, involved in the control of chromosome movement in mitosis and meiosis.
Splice site Location in the DNA sequence where RNA removes the noncoding areas to form a continuous gene transcript for translation into a protein.
spliceosome A complex of small nuclear ribonucleoproteins and other proteins that assemble on an immature mRNA and catalyse the excision of an intron. See: splicing.
Splicing 1. During the maturation of eukaryotic mRNA, the process that removes intron sequences and covalently joins exon sequences. Synonym: editing. 2.
splicing junction The DNA sequence immediately surrounding the boundary between an exon and an intron.
split gene In eukaryotes, the encoding DNA of many structural genes is made up of exons and introns .
spontaneous mutation A mutation occurring in the absence of any known mutagen.
Sporadic cancer Cancer that occurs randomly and is not inherited from parents. Caused by DNA changes in one cell that grows and divides, spreading throughout the body.
sporangium (pl.: sporangia) A reproductive structure in plants that produces spores. A megasporangium produces megaspores, which give rise to the female gametophyte…
Spore A term used to describe a particle in plants, bacteria and fungi.
spore mother cell Synonym of sporocyte.
sporocyte A diploid germ line cell that is the parent of the four haploid spores generated by meiosis.
sporophyll A leaf that bears sporangia.
sporophyte The diploid generation in the life cycle of a plant, and that produces haploid spores by meiosis.
sport An individual plant, or portion thereof, showing a recognizably different phenotype from the parent, presumably as a result of spontaneous mutation.
ssDNA Abbreviation for single-stranded DNA.
SSR Abbreviation for simple sequence repeat. See: microsatellite.
stacked genes Refers to the insertion of two or more genes into the genome of an organism. An example would be a plant carrying a giving insect resistance, and a bar…
stages of culture (I-IV) See: micropropagation.
staggered cuts Symmetrically cleaved phosphodiester bonds that lie on both strands of double-stranded DNA, but are not opposite one another.
stamen Floral structure made up of an anther and a filament. The stamen is the male organ of a flower.
Standard deviation Standard deviation is a statistical measurement of how far a variable quantity, such as the price of a stock, moves above or below its average value.
standard error The standard error of an estimate is a measure of the sampling variability of the estimate.
starch A substance found in plants. It contains sugar molecules joined chemically. It is found in high levels in foods such as potatoes, rice, corn, and wheat.
StarLinkTM An insect-resistant variety of corn that was approved for animal feed only, not labeled for human consumption.
start codon The codon which specifies the first amino acid of a polypeptide chain and at which the ribosome starts the process of translation.
starter culture Micro-organisms that are deliberately added to foods to alter flavour, colour, texture, smell, or taste.
stationary culture A culture maintained without agitation.
Stationary phase The plateau of the growth curve after log growth, during which cell number remains constant. New cells are produced at the same rate as older cells die.
steady state In a continuous fermentation process, the condition under which the number of cells removed with the outflow is exactly balanced by the number of newly…
Steel factor See stem cell factor.
stele The central vascular cylinder, inside the cortex, of roots and stems of higher plants.
stem The main body of the above-ground portion of a tree, shrub, herb or other plant; the ascending axis, whether above or below ground, of a plant.
Stem cell A cell from which other types of cells develop. For example, blood cells develop from blood-forming stem cells.
Stem cell antigen 1 (Sca-1) Cell-surface protein on bone marrow cell, indicative of hematopoietic stem cells and mesenchymal stem cells.
Stem cell factor (SCF) Relatively undifferentiated cell that can continue dividing indefinitely, throwing off daughter cells that can undergo terminal differentiation into…
Stem cells cells that have the ability to divide for indefinite periods in culture and give rise to specialized cells.
sterile (STER-il) Unable to produce children. Also means free from germs.
sterile room Dedicated space for the carrying out of activities that require sterile conditions.
sterility Complete or partial failure of an individual to produce functional gametes or viable zygotes under a given set of environmental conditions.
sterilize 1. The elimination of micro-organisms, using heat, irradiation, filtration or chemicals. 2.
Steward bottle Flask developed for the growth of cells and tissues in a liquid medium, in which they can be periodically submerged during rotation.
Sticky end A protruding, single-stranded nucleotide se- quence produced when a restriction endonuclease cleaves off center in its recognition sequence.
stigma Receptive portion of the style, to which pollen adheres.
stirred-tank fermenter A growth vessel in which cells or micro-organisms are mixed by mechanically-driven impellers.
stock A share of stock that represents ownership in the company that issues it. The price of the stock goes up and down, depending on how the company performs…
stock plant The source plant from which cuttings or explants are obtained. Stock plants should be well maintained to optimize explant and cutting quality.
stock solution Pre-prepared solution of commonly used reagents.
Stolon A lateral stem that grows horizontally along the ground surface. Used by some plant species as a mechanism for dispersal, since stolon nodes can…
stoma (STOH-muh) A surgically created opening from an area inside the body to the outside.
stomatal complex Includes the stoma, together with its guard cells and, when present, any related subsidiary cells.
stomatal index A measurement of the surface density of stoma ta. This parameter has been found useful in comparing leaves of different sizes.
Stop codon See Termination codon.
STR Strength
Strain A genetic variant within a species.
Stratification Layering of a lake, by temperature, during warmer seasons.
streptavidin A small bacterial protein that binds with high affinity to the vitamin biotin. This streptavidin-biotin combination can be used to link molecules such as…
Stress The response of the body to physical, mental, or emotional pressure. This may make a person feel frustrated, angry, or anxious, and may cause unhealthy…
stress protein (... PROH-teen) One of a group of proteins that help protect cells from stresses such as heat, cold, and low amounts of oxygen or glucose (sugar).
Stringency Reaction conditions--notably temperature, salt, and pH--that dictate the annealing of single-stranded DNA/DNA, DNA/RNA, and RNA/RNA hybrids.
Stringent plasmid A plasmid that only replicates along with the main bacterial chromosome and is present as a single copy, or at most several copies, per cell. (See plasmid.
Stroma (stro' mah) the supporting tissue or matrix of an organ; as distinguished from the functional part of the organ.
Stromal Relating to the stroma of an organ or other structure, that is, its framework, usually of connective tissue, rather than its specific substance.
Stromal cell (STROH-mul SEL) A type of cell that makes up certain types of connective tissue (supporting tissue that surrounds other tissues and organs).
Stromal cells Non-blood cells derived from blood organs, such as bone marrow or fetal liver, which are capable of supporting growth of blood cells in vitro.
structural gene A gene that encodes a polypeptide, with either enzymatic or structural functions, and that is required for the normal metabolism and growth of a cell or…
Structural genomics The effort to determine the 3D structures of large numbers of proteins using both experimental techniques and computer simulation
Structure-functionalism The scientific tradition that stresses the relationship between a physical structure and its function, for example, the related disciplines of anatomy and…
STS See Sequence\-tagged site.
style Slender column of tissue that arises from the top of the ovary and terminates in the stigma, and through which the pollen tube must grow to achieve…
sub-clone A procedure in which a large cloned DNA molecule is divided into smaller fragments, each one of which is then separately cloned.