Food Biotechnology terms starting with L

110 terms

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…
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.
labelling The process of attaching or inserting a label into a molecule. Most often in the context of nucleic acids or protein s.
lac repressor-lac promoter system See: IPTG.
lactose A type of sugar found in milk and milk products.
Lag phase The initial growth phase, during which cell number remains relatively constant prior to rapid growth. See growth phase.
lagging strand The strand of DNA that is synthesized discontinuously during replication (because DNA synthesis can proceed only in the 5'?3' direction).
lambda chain One of two classes of antibody light chains. The other is a kappa chain.
lambda phage A bacteriophage that infects E. coli, commonly used as a cloning vector. See: integration-excision region.
lamella A structure, plate or vesicle that is formed by two membranes lying parallel to each other.
lamina Blade or expanded part of a leaf.
laminar air-flow cabinet Cabinet designed for cell or tissue culture manipulations requiring a sterile environment.
laminarin A storage polysaccharide of the brown algae.
lampbrush chromosome Large diplotene chromosomes present in oocyte nuclei, and particularly conspicuous in amphibians.
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…
latent agent A pathogen, usually a virus, present in a host organism without producing any symptoms.
latent bud An inactive bud not held back by rest or dormant period, but which may start growth if stimulated.
latent phase See: lag phase.
lateral bud See: axillary bud.
lateral meristem A meristem giving rise to secondary plant tissues, such as the vascular and cork cambia.
Lawn A uniform and uninterrupted laver of bacterial growth, in which individual colonies cannot be observed.
layering A technique for vegetative propagation, in which new plants produce adventitious roots before being severed from the parent plant.
LCR Abbreviation for ligase chain reaction.
LD50 Abbreviation for lethal dose50%. The amount of a substance required to kill 50% of the test population.
lead compound A chemical that has demonstrated promising biological activity in preliminary assays.
leader peptide See: signal sequence.
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…
leading strand The strand of DNA that is synthesized continuously during replication.
leaf blade The usually flattened portion of the leaf.
leaf bud cutting A cutting that includes a short section of stem with attached leaf.
leaf margin The edge of a leaf.
leaf primordium A lateral outgrowth from the apical meristem, which will become a leaf when fully developed and expanded.
leaf roll A symptom of some virus diseases, characterized by curling of the leaves. Can also occur as a response to water stress.
leaf scar Mark left on a stem after leaf abscission.
leaflet Expanded leaf-like part of a compound leaf.
leaky mutant A mutant in which the gene product still retains some biological activity.
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.
Legume A member of the pea family that possesses root nodules containing nitrogen-fixing bacteria.
leptonema Stage in meiosis immediately preceding synapsis and post DNA replication, in which the chromosomes appear as single, fine, threadlike structures.
leptotene (adj.) See: leptonema.
lethal allele A mutant form of a gene that, in the homozygous state, is fatal.
lethal gene See: lethal allele.
lethal mutation See: lethal allele.
Leukocyte (LOO-koh-site) A white blood cell. Refers to a blood cell that does not contain hemoglobin.
library A collection of cells, usually bacteria or yeast, that have been transformed with recombinant vectors carrying DNA inserts from a single species.
life cycle The sequence of events from a given developmental stage in one generation to the same stage in the following generation.
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…
ligase See: DNA ligase.
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'…
ligase chain reaction (Abbreviation: LCR). A technique for the detection and amplification of target DNA sequences.
Ligate The process of joining two or more DNA fragments.
ligate, ligation The joining of two linear double-stranded DNA fragments by the formation of phosphodiester bonds.
lignification The thickening and strengthening of a plant cell wall with lignin.
lignin A group of high-molecular-weight amorphous polymers of phenylpropanoid compounds, giving strength to certain tissues. A major component of wood.
lignocellulose The combination of lignin, hemicellulose and cellulose that forms the structural framework of plant cell walls.
line See Groove
Lineage A chart that traces the flow of genetic information from generation to generation.
linear phase The growth phase during cell culture when cell number increases arithmetically. The linear phase follows a period of exponential growth.
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.
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…
Linkage disequilibrium See: gametic phase disequilibrium.
linkage equilibrium See: gametic phase equilibrium.
Linkage map See Genetic linkage map.
linked gene, linked marker A gene or marker that is linked to another gene or marker.
Linked genes/markers Genes and/or markers that are so closely associated on the chromosome that they are coinherited in 80% or more of cases.
linker A short, double-stranded oligonucleotide containing a restriction endonuclease recognition site, which is ligated to the ends of a DNA fragment.
Lipase A class of enzymes which break down lipids into their component fatty acids and glycerol.
lipid Fat.
lipofection Delivery into eukaryotic cells of DNA, RNA or other compounds that have been encapsulated in liposomes.
lipopolysaccharide (Abbreviation: LPS). A compound containing lipid bound to a polysaccharide; often a component of microbial cells walls.
liposome (LY-puh-some) A very tiny, fat-like particle that is made in the laboratory. In medicine, liposomes containing drugs or other substances are used in the…
Liposomes Membrane-bound vesicles constructed in the laboratory to transport biological molecules.
Liquefaction Enzymatic digestion (often by alpha-amylase) of gelatinized starch to form lower molecular weight polysaccharides.
liquid medium Culture solution, without a solidifying agent, for in vitro cell growth.
liquid membrane Thin films made up of liquids (as opposed to solids) which are stable in another liquid (usually water).
liquid nitrogen Nitrogen gas condensed to a liquid with a boiling point of about -196 °C. Commonly used as a medium for long-term storage of biological materials.
litmus paper A pH indicator paper. It turns red in acidic and blue in alkaline solutions.
live recombinant vaccine A vaccine created by the expression of a pathogen antigen in a non-pathogenic organism.
live vaccine A living, non-virulent form of a pathogenic micro-organism or virus used to elicit an antibody response for the protection against infection by a virulent…
living modified organism (Abbreviation: LMO). "Living organism that possess a novel combination of genetic material obtained through the use of modern biotechnology " (Convention…
LMO Abbreviation for living modified organism
locus (LOH-kuss) Specific place where something is located or occurs. It may refer to a specific place on the body (such as an acupuncture point) or the place…
Locus (plural = loci) A specific location or site on a chromosome.
LOD score The logarithm of the odds of linkage between two loci. Used to measure the statistical support for linkage.
Log phase See Logarithmic phase.
logarithmic phase The growth phase in cell culture, during which cell number doubles every 20-30 minutes. Synonym: exponential phase.
Logarithmic phase (log or exponential growth phase) The steepest slope of the growth curve--the phase of vigorous growth during which cell number doubles every 20-30 minutes. (See Growth phase.)
long interspersed nuclear element (Abbreviation: LINE). Families of common DNA elements, of average length 6.5 kb, which are dispersed at numerous locations within the genome.
long template A DNA strand, synthesized during PCR, which has a primer sequence at one end but is extended beyond the site that is complementary to the second primer at…
long terminal repeat (Abbreviation: LTR). A characteristic sequence of nucleotides that occurs at each end of a retrovirus element that has become integrated into the host…
long-day plant Plants requiring a period of short nights before the switch from vegetative to reproductive growth can be initiated. See: Short-day plant.
loop bioreactor Fermenters in which material is cycled between a bulk tank and a smaller tank or loop of pipes.
LPS Abbreviation for lipopolysaccharide.
LTR Abbreviation for long terminal repeat.
luteinizing hormone A pituitary hormone which causes growth of the yellow body of the ovary and also stimulates activity of the interstitial cells of the testis.
luxury consumption Nutrient absorption by an organism in excess of that required for optimum growth and productivity.
lyase Any of a class of enzymes that catalyse either the cleavage of a double bond and the addition of new groups to a substrate, or the formation of a double…
Lymphocyte (LIM-foh-site) A type of white blood cell. Lymphocytes have a number of roles in the immune system, including the production of antibodies and other…
lymphokine Generic name for proteins that are released by lymphocyte s to act on other cells involved in the immune response.
lymphoma (lim-FOH-muh) Cancer that begins in cells of the immune system. There are two basic categories of lymphomas.