Food Biotechnology terms starting with R

168 terms

R genes A class of plant genes conferring resistance to a specific strain (or group of strains) of a particular pathogen.
R-loops Single-stranded DNA regions in RNA -DNA hybrids formed in vitro under conditions where RNA -DNA duplexes are more stable than DNA -DNA duplexes.
R1 The first-generation offspring of a recombinant (genetically modified) organism. Not standard terminology. See: T0, T1, and T2.
RACE A distinguishable group of organisms of a particular species. Criteria for distinctness can be one or a combination of geographic, ecological…
raceme An inflorescence in which the main axis is elongated but the flowers are borne on pedicels that are about equal in length.
rachilla Shortened axis of a spikelet.
rachis Main axis of a spike; axis of fern leaf (frond) from which pinnae arise; in compound leaves, the extension of the petiole corresponding to the midrib of…
radiation hybrid cell panel (Abbreviation: RH). A somatic cell hybrid panel in which the chromosomes from the species of interest have been fragmented by irradiation prior to cell…
radicle The portion of the plant embryo which develops into the primary root.
Radioimmunoassay (Abbreviation: RIA). An assay based on the use of a radioactively labelled antibody, where the amount of radiation detected indicates the amount of target…
radioisotope (RAY-dee-oh-I-suh-tope) An unstable form of a chemical element that releases radiation as it breaks down and becomes more stable.
raft culture See: nurse culture.
ramet An individual member of a clone, descended from the ortet.
random amplified polymorphic DNA (Abbreviation: RAPD). A PCR -based genotyping technique in which genomic template is amplified with single, short (usually 10-mer) randomly chosen primers.
random genetic drift See: genetic drift.
random mutagenesis A non-directed change of one or more nucleotide pairs in a DNA molecule.
random primer method A method for labelling DNA probes, mainly for Southern hybridization experiments.
RAPD Abbreviation for random amplified polymorphic DNA.
rate-limiting enzyme The enzyme whose activity controls the output of final product from a multi-enzyme metabolic pathway.
rational drug design A systematic method of creating compounds by analysing their structure, function and stereochemical interactions.
read-through Transcription or translation that proceeds beyond the normal stopping point because of the absence of the usual transcription or translation termination…
Reading frame A series of triplet codons beginning from a specific nucleotide. Depending on where one begins, each DNA strand contains three different reading frames.
recA A protein, found in most bacteria, that is essential for DNA repair and DNA recombination.
recalcitrant Of seeds, unable to survive drying and subsequent storage at low temperature. See: field gene bank.
receptacle Enlarged end of the pedicel or peduncle, to which other flower parts are attached.
receptor (reh-SEP-ter) A molecule inside or on the surface of a cell that binds to a specific substance and causes a specific physiologic effect in the cell.
receptor-binding screening A biotechnology-based method for drug discovery, which relies on the fact that many drugs act by binding to specific receptors on or in cells.
recessive Describing an allele whose effect with respect to a particular trait is not evident in heterozygotes. Opposite: dominant.
recessive allele Allelic state of a gene, where homozygosity is required for the expression of the relevant phenotype. Opposite:.
Recessive gene Characterized as having a phenotype expressed only when both copies of the gene are mutated or missing.
recessive oncogene A single copy of this gene is sufficient to suppress cell proliferation; the loss of both copies of the gene contributes to cancer formation.
Recessive(-acting) oncogene, (anti-oncogene) A single copy of this gene is sufficient to suppress cell proliferation; the loss of both copies of the gene contributes to cancer formation.
recessive-acting oncogene See: recessive oncogene.
reciprocating shaker A platform shaker used for agitating culture flasks, with a back and forth action at variable speeds.
recognition sequence Synonym of recognition site.
Recognition sequence (site) A nucleotide sequence--composed typically of 4, 6, or 8 nucleotides--that is recognized by a restriction endonuclease.
recognition site A nucleotide sequence, typically 4-8bp long and often palindromic, that is recognized by, and at which a restriction endonuclease binds to the DNA.
recombinant (ree-KOM-bih-nunt) In genetics, describes DNA, proteins, cells, or organisms that are made by combining genetic material from two different sources.
recombinant DNA The process of cutting and recombining DNA fragments from different sources as a means to isolate genes or to alter their structure and function.
Recombinant DNA molecules (rDNA) A combination of DNA molecules of different origin that are joined using recombinant DNA technologies.
Recombinant DNA technology A set of techniques for manipulating DNA, including: the identification and cloning of genes; the study of the expression of cloned genes; and the…
recombinant human (Abbreviation rh). A prefix denoting molecules made through the use of recombinant DNA technology.
recombinant protein A protein encoded by a cloned gene. Synonym: heterologous protein.
recombinant RNA RNA molecules joined in vitro by T4 RNA ligase.
recombinant toxin A single multifunctional toxic protein encoded by a recombinant gene.
recombinant vaccine A vaccine produced from a cloned gene.
recombinase A class of enzymes that are able to alter the arrangement of DNA sequences in a site-specific way.
Recombination The production of a DNA molecule with segments derived from more than one parent DNA molecule.
recombination fraction The proportion of recombinant (with respect to two loci) gametes arising from meiosis.
Recombination frequency The frequency at which crossing over occurs between two chromosomal loci--the probability that two loci will become unlinked during meiosis.
recombinational hot spot A chromosomal region where recombination appears to occur more frequently than expected.
reconstructed cell A viable transformed cell resulting from genetic engineering.
reduction division The first division of meiosis in which the chromosome number is reduced from the somatic to the gametic number.
refugium (pl.: refugia) An area set aside to provide protection/escape from ecological consequences occurring elsewhere.
regeneration In biology, regrowth of damaged or destroyed tissue or body part.
regulator Substance regulating growth and development of cells, organs, etc.
Regulatory gene A gene whose protein controls the activity of other genes or metabolic pathways.
regulatory sequence A DNA sequence involved in regulating the expression of a gene, e.g. a promoter or operator region (in the DNA molecule).
rejuvenation 1. Reversion from adult to juvenile stage. 2. The process of regular reproduction of seed stocks or collections in gene banks, in order to ensure…
relaxed circle See: nicked circle.
Relaxed circle plasmid See Plasmid.
Relaxed plasmid A plasmid that replicates independently of the main bacterial chromosome and is present in 10-500 copies per cell. (See Plasmid.)
release factor 1. A soluble protein that recognizes termination codon s in mRNA s and terminates translation in response to these codons. 2.
Remediation The cleanup or containment of a hazardous waste disposal site to the satisfaction of the applicable regulatory agency.
renaturation Of DNA, the reforming of two complementary molecules into a double-stranded structure, following heat or chemical induction of dissociation (denaturation).
Renature The reannealing (hydrogen bonding) of single- stranded DNA and/or RNA to form a duplex molecule.
rennin An enzyme, secreted by cells lining the stomach in mammals, responsible for the clotting of milk. Used in the manufacture of certain dairy products.
repeat unit A sequence of nucleotide s that occurs repeatedly, often in a head-to-tail arrangement (tandemly).
Repetitive DNA DNA sequences that are present in a genome in many copies, some of it originating from retrotransposon activity.
replacement The addition of a cloned corrected copy of a defective gene. See: homogenotization.
replacement therapy The administration of metabolites, co-factors or hormones that are deficient as the result of a genetic disease.
replica plating Duplicating a population of bacterial colonies growing on agar medium in one Petri plate to agar medium in another Petri plate.
replicase A viral enzyme necessary for the replication of the virus in the host cell.
Replication The in vivo synthesis of double-stranded DNA by copying from a single-stranded template.
replication fork Y shaped structure associated with DNA replication. It represents the point at which the strands of double-stranded DNA are separated so that replication…
replicative form (Abbreviation: RF). The molecular configuration of viral nucleic acid that is the template for replication in the host cell.
Replicon A chromosomal region containing the DNA sequences necessary to initiate DNA replication processes.
replisome The complete replication apparatus, present at a replication fork, that carries out the replication of DNA.
Reporter gene A gene that encodes a product that can be readily assayed. Used as to confirm the incorporation of a transgene into, organ or tissue, and as a means of…
repressible enzyme An enzyme whose activity can be diminished by the presence of a regulatory molecule.
repressible gene A gene whose expression can be diminished or extinguished by the presence of a regulatory molecule.
repression Inhibition of transcription by preventing RNA polymerase from binding to the transcription initiation site.
repressor A DNA-binding protein in prokaryotes that blocks gene transcription by binding to the operator.
reproduction 1. Sexual reproduction: the regular alteRNA tion of meiosis and fertilization which provides for the production of offspring.
repulsion A double heterozygote in which the dominant (or wild-type) allele at one locus and the recessive (or mutant) allele at a second linked locus occur on the…
residue 1. See: polymer. 2. Materials remaining after degradation and/or attempted removal, e.g. pesticide residues in food.
Resistance The ability of an organism to develop ways to be impervious to specific threats to their existence.
resistance factor A plasmid that confers antibiotic resistance to a bacterium.
Resistance management Strategies that can delay the onset of resistance. For insect resistance management, this includes the use of a refuge in which the insect will not be…
rest period A physiological condition of viable seed s, buds or bulbs that prevents growth even in the presence of otherwise favourable environmental conditions.
restitution nucleus A single nucleus arising from a failure of nuclear division, either during meiosis, in which a gamete is formed with the unreduced chromosome number; or…
restriction endonuclease A class of enzymes that cut DNA after recognizing a specific sequence. The three types of restriction endonuclease are: I.
Restriction endonuclease (enzyme) A class of endonucleases that cleaves DNA after recognizing a specific sequence, such as BamH1 (GGATCC), EcoRI (GAATTC), and HindIII (AAGCTT). Type I.
restriction enzyme Synonym of restriction endonuclease.
restriction exonuclease A class of enzymes that degrade DNA or RNA, starting from either the 5'- or the 3'-end.
restriction fragment A shortened DNA molecule generated by the cleavage of a larger molecule by one or more restriction endonucleases.
restriction fragment length polymorphism (Abbreviation: RFLP). A class of genetic marker based on the detection of variation in the length of restriction fragments generated when DNA is treated…
Restriction fragment length polymorphism (RFLP) Differences in nucleotide sequence between alleles at a chromosomal locus result in restriction fragments of varying lengths detected by Southern analysis.
Restriction map See Mapping.
restriction site Synonym of recognition site.