Biotechnology and Genetics terms starting with S

345 terms

  1. sex duction The incorporation of bacterial genes into F factors and their subsequent transfer, by conjugation, to a recipient cell.
  2. sex factor A bacterial episome (e.g. the F plasmid in E. coli ) that enables the cell to be a donor of genetic material.
  3. sex hormones Steroid hormones that control sexual development in animals.
  4. sex linkage Referring to genes present on one of the sex chromosomes, thus genetically linked to the sex of the individual.
  5. sex mosaic Synonym of gynandromorph.
  6. sex-influenced dominance The tendency for gene action to vary between the sexes within a species. For example, the presence of horns in some breeds of sheep appears to be dominant…
  7. sex-limited Expression of a trait in only one sex; e.g. milk production in mammals; egg production in chickens.
  8. Sex-linked Located on the X chromosome. Sex-linked (or x-linked) diseases are generally seen only in males. See also gene, mutation
  9. sexed embryos Embryos separated according to sex.
  10. Sexual reproduction The process where two cells (gametes) fuse to form one hybrid, fertilized cell. See Asexual reproduction, Gamete, Hybrid.
  11. shake culture An agitated suspension in culture providing adequate aeration for cells in the liquid medium.
  12. shaker A platform, with set or variable speed control, used to agitate vessels containing liquid cell cultures. Also described as a platform shaker.
  13. Shear Literally the sliding of one layer across another, with deformation and fracturing in the direction parallel to the movement.
  14. Shine-Dalgarno sequence A conserved sequence of prokaryotic mRNAs that is complementary to a sequence near the 5' terminus of the 16S ribosomal RNA and is involved in the…
  15. shoot apex See: shoot tip.
  16. shoot differentiation The development of growing points, leaf primordia and finally shoots from a shoot tip, axial bud, or callus surface.
  17. shoot tip The terminal bud (0.1 - 1.0 mm) of a plant, which consists of the apical meristem (0.05 - 0.
  18. shoot-tip graft A shoot tip or meristem tip grafted onto a prepared seedling or micropropagated rootstock in culture.
  19. short interspersed nuclear element (Abbreviation: SINE ). Families of short (150-300 bp), moderately repetitive DNA elements of eukaryotic genomes.
  20. short-day plant A plant which will not flower until triggered to do so by exposure to one or a number of dark periods equal to or longer than its critical period.
  21. shotgun genome sequencing A strategy for sequencing a whole genome, in which the genomic DNA is initially fragmented into pieces small enough to be sequenced.
  22. Shotgun method Sequencing method that involves randomly sequenced cloned pieces of the genome, with no foreknowledge of where the piece originally came from.
  23. shotgun sequencing An approach used to decode an organism's genome by shredding it into smaller fragments of DNA which can be sequenced individually.
  24. shuttle vector A plasmid capable of replicating in two different host organisms because it carries two different origins of replication and can therefore be used to…
  25. sib-mating The deliberate crossing of siblings. Generally done where self-incompatibility prevents the production of self-fertilized progeny.
  26. sickle cell disease (SIH-kul sel dih-ZEEZ) An inherited disease in which the red blood cells have an abnormal crescent shape, block small blood vessels, and do not last as…
  27. Side population (SP) stem cell Two examples of multipotent stem cell populations found in bone marrow and skeletal muscle. SPs are not yet fully characterized.
  28. siderophore A low molecular weight entity that binds very tightly to iron. Siderophores are synthesized by a variety of soil micro-organisms to ensure that the…
  29. sieve cell A long and slender sieve element in vascular plants, characterized by relatively unspecialized sieve areas and tapering end walls that lack sieve plates.
  30. sieve element The phloem cell concerned with longitudinal conduction of food materials.
  31. sieve plate Perforated wall area in a sieve tube element, through which strands connecting sieve tube protoplasts can pass.
  32. sieve tube A tube within the phloem tissue of a plant, composed of joined sieve elements.
  33. sigma factor The sub-unit of prokaryotic RNA polymerases responsible for the initiation of transcription at specific initiation sequences.
  34. signal peptide See: signal sequence.
  35. signal sequence A stretch of 15-30 amino acid residues at the N terminus of a protein, which is thought to enable the protein to be secreted (pass through a cell…
  36. signal transduction (SIG-nul trans-DUK-shun) The process by which a cell responds to substances in its environment.
  37. Signal transduction pathways Relay of a signal by the conversion from one physical or chemical form to another.
  38. Signal-to-Noise Ratio A specifically produced response (signal) compared to the response level (noise) when no specific stimulus (activity) is present.
  39. Signals Internal and external factors that control changes in cell structure and function.
  40. silencing Loss of gene expression either through an alteration in the of a structural gene, or its regulatory region; or because of interactions between its…
  41. silent mutation See: mutation.
  42. simple sequence repeat (Abbreviation: SSR). See: microsatellite.
  43. SINE Without.
  44. single copy A gene or DNA sequence which occurs only once per (haploid ) genome. Many structural genes are single copy.
  45. single domain antibody See: dAb.
  46. single node culture Culture of separate lateral bud s, each carrying a piece of stem tissue.
  47. single nucleotide polymorphism (... NOO-klee-oh-TIDE PAH-lee-MOR-fih-zum) The most common type of change in DNA (molecules inside cells that carry genetic information).
  48. Single nucleotide polymorphism (SNP) DNA sequence variations that occur when a single nucleotide (A, T, C, or G) in the genome sequence is altered.
  49. single nucleotide polymorphisms (SNPs) Common, but minute, variations that occur in human DNA at a frequency of one every 1,000 bases.
  50. single primer amplification reaction (Abbreviation: SPAR). A PCR-based genotyping technique in which genomic template is amplified with a single primer.
  51. Single-cell cloned A procedure pertaining to cells in vitro in which the descendants of a single cell are physically isolated from other cells growing in a dish, and then…
  52. single-cell line See: cell strain.
  53. single-cell protein (Abbreviation: SCP). Protein produced by micro-organisms, particularly yeast. Used as either a feed or a food additive.
  54. Single-gene disorder Hereditary disorder caused by a mutant allele of a single gene (e.g., Duchenne muscular dystrophy, retinoblastoma, sickle cell disease).
  55. single-strand conformational polymorphism (Abbreviation: SSCP). A technique for detection of mutations in a defined DNA sequence.
  56. single-strand DNA binding protein A protein that coats single-stranded DNA, preventing renaturation and so maintaining the DNA in an extended state.
  57. single-stranded DNA (Abbreviation: ssDNA). DNA molecules separated from their complementary strand, either by its absence or following denaturation.
  58. single-stranded nucleic acid Nucleic acid molecules consisting of only one polynucleotide chain. The genomes of many viruses are single-stranded DNA molecules, as are most…
  59. SIRE Male animal chosen for breeding.
  60. sister chromatid exchange (Abbreviation: SCE). Reciprocal interchanges of the two chromatid arms within a single chromosome.
  61. Site-directed mutagenesis The process of introducing spe- cific base-pair mutations into a gene.
  62. Site-Specific A term used to describe any process or enzyme which acts at a defined sequence within a DNA or RNA molecule.
  63. site-specific mutagenesis The induction of mutation s, by molecular biology techniques, in one or more specific nucleotide s within a defined coding sequence in order to create…
  64. sitosterol See: phytosterol.
  65. six-base cutter Type II restriction endonucleases whose recognition site and cleavage site consist of a characteristic sequence of six nucleotide pairs.
  66. Skin biopsy Process of removing tissue, in this case skin, from living patients for diagnostic examination, or the tissue specimen obtained by that process.
  67. small nuclear ribonucleoprotein (Abbreviation: snRNP). A complex of small nuclear RNA and nuclear protein, heavily involved in the post-transcriptional processing of mRNA, especially the…
  68. small nuclear RNA (Abbreviation: snRNA ). RNA transcripts of 100-300 bp that associate with proteins to form small nuclear ribonucleoprotein particles.
  69. Small nuclear RNA (snRNA) Short RNA transcripts of 100-300 bp that associate with proteins to form small nuclear ribonucleoprotein particles (snRNPs), which participate in RNA…
  70. SNP The most common type of change in DNA (molecules inside cells that carry genetic information).
  71. snRNA See Small nuclear RNA.
  72. snRNP Abbreviation for small nuclear ribonucleoprotein.
  73. sodium dodecyl sulphate (Abbreviation: SDS). A detergent used to solubilize protein and DNA from biological materials.
  74. sodium dodecyl sulphate polyacrylamide gel electrophoresis (Abbreviation: SDS-PAGE). A widely employed electrophoretic method for the separation of proteins from biological samples.
  75. soil amelioration The improvement of poor soils. Includes the fungal and bacterial break down of plant organic matter, to form humus; the release of minerals - such as…
  76. Soil conservation practices See minimal tillage practices.
  77. soil-less culture Growing plants in nutrient solution without soil. Synonym: hydroponics.
  78. solid medium Nutrient medium solidified by the addition of a gelling agent, commonly agar.
  79. somaclonal variation Epigenetic or genetic changes induced during the callus phase of plant cells cultured in vitro.
  80. somatic (soh-MA-tik) Having to do with the body.
  81. Somatic cell (soh-MA-tik ...) Any of the body cells except the reproductive (germ) cells.
  82. somatic cell embryogenesis The process of differentiation of somatic embryos either from explant cells (direct embryogenesis), or from callus generated from explants (indirect…
  83. Somatic cell gene therapy The repair or replacement of a defective gene within somatic tissue. (See Somatic cell.)
  84. Somatic cell genetic mutation A change in the genetic structure that is neither inherited nor passed to offspring. Also called acquired mutations. See also: germ line genetic mutation
  85. somatic cell hybrid panel A panel of cells created by cell fusion, typically involving a reference species (e.g. hamster) and the species of interest (e.g.
  86. Somatic cell nuclear transfer A technique in which the nucleus of a somatic cell (any cell of the body except sperm cells and egg cells) is injected, or transfered, into an egg, that…
  87. Somatic Cell Nuclear Transfer (SCNT) A method of cloning: transfer of the nucleus from a donor somatic cell into an enucleated egg to produce a cloned embryo.
  88. somatic cell variant A somatic cell with unique characters not present in the other cells, and which could be selected for by an appropriate screen.
  89. Somatic cells Cells of body tissues other than the germline.
  90. somatic embryo An organized embryo -like structure. Although morphologically similar to a zygotic embryo it is initiated from somatic plant cells.
  91. somatic hybridization Naturally occurring or induced fusion of somatic protoplasts or cells of two genetically different parents. The difference may be as wide as interspecific.
  92. somatic hypermutation The high frequency of mutation that occurs in the gene segments encoding the variable regions of immunoglobulins during the differentiation of B…
  93. somatic reduction Halving of the chromosomal number of somatic cells; a possible method of producing "haploids" from somatic cells and calli by artificial means.
  94. Somatic stem cells Non-embryonic stem cells that are not derived from gametes (egg or sperm cells).
  95. somatocrinin Growth hormone-releasing hormone. See: growth hormone.
  96. Somatostatin Growth hormone-inhibiting hormone. See: growth hormone.
  97. Somatotrophin See Human growth hormone.
  98. somatotropin (SOH-muh-toh-TROH-pin) A protein made by the pituitary gland that helps control body growth and the use of glucose and fat in the body.
  99. Somite One of the longitudinal series of segments into which the body of many animals (including vertebrates) is divided. (Merriam-Webster on line)
  100. sonication Disruption of cells or DNA molecules by high frequency sound waves.