Biotechnology and Genetics — page 21 of 40

3,925 terms including subtopics (0 terms filed directly here)

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Biotechnology and Genetics terms

  1. Kanamycin An antibiotic of the aminoglycoside family that poisons translation by binding to the ribosomes.
  2. kanr Kanamycin resistance gene. (See Selectable marker.)
  3. kappa chain One of two classes of antibody light chains. The other is a lambda chain.
  4. karyogamy The fusion of nuclei or nuclear material that occurs at fertilization during sexual reproduction.
  5. karyogram A diagrammatic representation of the full chromosome set of a species, highlighting characteristic physical features of individual chromosomes.
  6. karyokinesis The division of a cell nucleus. See: meiosis; mitosis.
  7. Karyotype All of the chromosomes in a cell or an individual organism, visible through a microsope during cell division.
  8. KB Abbreviation for kilobase (of single-stranded nucleic acid).
  9. kbp Abbreviation for kilobase pairs (of double-stranded DNA ).
  10. kcat The catalytic rate constant that characterizes an enzyme-catalysed reaction. The larger the kcat value, the faster the conversion of substrate into…
  11. kcat/Km The catalytic efficiency of an enzyme-catalysed reaction. The greater the value of kcat/Km, the more rapidly and efficiently the substrate is converted…
  12. Kd Abbreviation for dissociation constant. Describes the strength of binding (or affinity) between molecules and their ligands . See: avidity.
  13. kDa Abbreviation for kiloDalton. A unit of molecular mass equal to 1000 Dalton.
  14. Keratin An extremely tough protein substance found in hair, nails, skin, and cornea.
  15. Keratinocytes Cells that synthesize keratin and are found in the skin, hair, and nails. A fibrous protein is produced by keratinocytes and may be hard or soft.
  16. killer T cell T cells that kill cells displaying recognized antigens.
  17. kilobase (Abbreviation: kb). A length of single-stranded nucleic acid composed of 1000 bases.
  18. Kilobase (kb) Unit of length for DNA fragments equal to 1000 nucleotides.
  19. kilobase pairs (Abbreviation: kbp). A length of double-stranded DNA composed of 1000 base pairs.
  20. kinase An enzyme that catalyses the transfer of a phosphate group from a high energy state (as in ATP) to another molecule.
  21. kinetics Dynamic processes involving motion. Often used as a suffix to indicate studies involving movement or rates of reactions.
  22. kinetin A cytokinin.
  23. kinetochore Structure at the centromere of eukaryotic chromosomes. The kinetochore consists of inner and outer electron dense plates and a central zone containing…
  24. kinetosome Granular cytoplasmic structure which forms the base of a cilium or flagellum. Synonym: basal body.
  25. kinin A substance promoting cell division. In plant systems, the prefix cyto- has been added (cytokinin ) to distinguish it from kinin in animal systems.
  26. Klenow fragment A truncated form of DNA polymerase I from E. coli, used extensively for the production of synthetic DNA molecules as it retains polymerase and…
  27. Km A dissociation constant that characterizes the binding of an enzyme to a substrate.
  28. Knock In Replacement of a gene by a mutant version of the same gene using homologous recombination.
  29. Knock Out Inactivation of a gene by homologous recombination following transfection with a suitable DNA construct.
  30. Knock-out mouse A mouse that has had one or both copies of a specific gene deleted or inactivated.
  31. knockout A mutant individual, in which a single functional gene has been replaced by a non-functional form of the gene.
  32. label The FDA approved label is the official description of a drug product which includes indication (what the drug is used for); who should take it; adverse…
  33. Labeling of foods The process of developing a list of ingredients contained in foods. Labels imply that the list of ingredients can be verified. The U.S.
  34. labelling The process of attaching or inserting a label into a molecule. Most often in the context of nucleic acids or protein s.
  35. lac repressor-lac promoter system See: IPTG.
  36. lactose A type of sugar found in milk and milk products.
  37. Lacunae The spaces occupied by cells (e.g., chondrocytes and osteocytes) of calcified tissues.
  38. Lag phase The initial growth phase, during which cell number remains relatively constant prior to rapid growth. See growth phase.
  39. lagging strand The strand of DNA that is synthesized discontinuously during replication (because DNA synthesis can proceed only in the 5'?3' direction).
  40. lambda chain One of two classes of antibody light chains. The other is a kappa chain.
  41. lambda phage A bacteriophage that infects E. coli, commonly used as a cloning vector. See: integration-excision region.
  42. lamella A structure, plate or vesicle that is formed by two membranes lying parallel to each other.
  43. lamina Blade or expanded part of a leaf.
  44. laminar air-flow cabinet Cabinet designed for cell or tissue culture manipulations requiring a sterile environment.
  45. laminarin A storage polysaccharide of the brown algae.
  46. lampbrush chromosome Large diplotene chromosomes present in oocyte nuclei, and particularly conspicuous in amphibians.
  47. landrace In plant genetic resources, an early, cultivated form of a crop species, evolved from a wild population, and generally composed of a heterogeneous mixture…
  48. latent agent A pathogen, usually a virus, present in a host organism without producing any symptoms.
  49. latent bud An inactive bud not held back by rest or dormant period, but which may start growth if stimulated.
  50. latent phase See: lag phase.
  51. lateral bud See: axillary bud.
  52. lateral meristem A meristem giving rise to secondary plant tissues, such as the vascular and cork cambia.
  53. Lawn A uniform and uninterrupted laver of bacterial growth, in which individual colonies cannot be observed.
  54. layering A technique for vegetative propagation, in which new plants produce adventitious roots before being severed from the parent plant.
  55. LCR Abbreviation for ligase chain reaction.
  56. LD50 Abbreviation for lethal dose50%. The amount of a substance required to kill 50% of the test population.
  57. lead compound A chemical that has demonstrated promising biological activity in preliminary assays.
  58. leader peptide See: signal sequence.
  59. leader sequence A variable length sequence of nucleotides at the 5' end of an mRNA molecule that precedes the AUG initiation codon where translation begins and is not…
  60. leading strand The strand of DNA that is synthesized continuously during replication.
  61. leaf blade The usually flattened portion of the leaf.
  62. leaf bud cutting A cutting that includes a short section of stem with attached leaf.
  63. leaf margin The edge of a leaf.
  64. leaf primordium A lateral outgrowth from the apical meristem, which will become a leaf when fully developed and expanded.
  65. leaf roll A symptom of some virus diseases, characterized by curling of the leaves. Can also occur as a response to water stress.
  66. leaf scar Mark left on a stem after leaf abscission.
  67. leaflet Expanded leaf-like part of a compound leaf.
  68. leaky mutant A mutant in which the gene product still retains some biological activity.
  69. lectin A complex molecule that has both protein and sugars. Lectins are able to bind to the outside of a cell and cause biochemical changes in it.
  70. Lefty A developmental factor that helps determine right-left asymmetry in vertebrates.
  71. Legume A member of the pea family that possesses root nodules containing nitrogen-fixing bacteria.
  72. Leptin A hormone produced by the placenta and fetal tissues that acts as a growth factor and modulator of metabolic and immune functions.
  73. leptonema Stage in meiosis immediately preceding synapsis and post DNA replication, in which the chromosomes appear as single, fine, threadlike structures.
  74. leptotene (adj.) See: leptonema.
  75. lethal allele A mutant form of a gene that, in the homozygous state, is fatal.
  76. lethal gene See: lethal allele.
  77. lethal mutation See: lethal allele.
  78. leukemia (loo-KEE-mee-uh) Cancer that starts in blood-forming tissue such as the bone marrow and causes large numbers of blood cells to be produced and enter the…
  79. Leukemia inhibitory factor A cell messenger protein originally noted for inhibition of mouse M1 myeloid leukemia cells that also has effects including inhibiting differentiation to…
  80. Leukemia inhibitory factor (LIF) A growth factor necessary for maintaining mouse embryonic stem cells in a proliferative, undifferentiated state.
  81. Leukocyte (LOO-koh-site) A white blood cell. Refers to a blood cell that does not contain hemoglobin.
  82. Leukocyte (White Blood Cell) The general name for a white blood cell. Leukocytes are responsible for maintaining the immune system's response to foreign substances and infection.
  83. Leukocyte common antigen Cell-surface molecule found on white blood cells and white blood cell progenitors. Also referred to as CD45.
  84. library A collection of cells, usually bacteria or yeast, that have been transformed with recombinant vectors carrying DNA inserts from a single species.
  85. life cycle The sequence of events from a given developmental stage in one generation to the same stage in the following generation.
  86. ligand A small molecule (e.g. activators, substrates and inhibitors of enzyme activity) bound to a protein by non-covalent forces; an ion or a molecule that…
  87. ligase See: DNA ligase.
  88. Ligase (DNA ligase) An enzyme that catalyzes a condensation reaction that links two DNA molecules via the formation of a phosphodiester bond between the 3' hydroxyl and 5'…
  89. ligase chain reaction (Abbreviation: LCR). A technique for the detection and amplification of target DNA sequences.
  90. Ligate The process of joining two or more DNA fragments.
  91. ligate, ligation The joining of two linear double-stranded DNA fragments by the formation of phosphodiester bonds.
  92. lignification The thickening and strengthening of a plant cell wall with lignin.
  93. lignin A group of high-molecular-weight amorphous polymers of phenylpropanoid compounds, giving strength to certain tissues. A major component of wood.
  94. lignocellulose The combination of lignin, hemicellulose and cellulose that forms the structural framework of plant cell walls.
  95. line See Groove
  96. Lineage A chart that traces the flow of genetic information from generation to generation.
  97. Lineage surface antigen (Lin) A mixture of monoclonal antibodies that are directed against antigens found on mature hematopoietic cells of different lineages.
  98. linear phase The growth phase during cell culture when cell number increases arithmetically. The linear phase follows a period of exponential growth.
  99. linearized vector A covalently closed circular DNA vector (typically a plasmid ) which has been opened by restriction digestion to convert it to a linear molecule.
  100. linkage The frequency of coinheritance of a pair of genes and/or genetic markers, which provides a measure of their physical proximity to one another on a…