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Filebox - Biotechnology Dictionary
Category: Earth and Environment > Biotechnology
Date & country: 13/09/2007, USA
Words: 456


Introgression
Backcrossing of hybrids of two plant populations to introduce new genes into a wild population.

Intron
A noncoding DNA sequence within a gene that is initially transcribed into messenger RNA but is later snipped out. See Coding, DNA, Messenger RNA, Transcription.

Invasiveness
Ability of a plant to spread beyond its introduction site and become established in new locations where it may provide a deliterious effect on organisms already existing there.

Ion
A charged particle.

Isotope
One of two or more forms of an element that have the same number of protons (atomic number) but differing numbers of neutrons (mass numbers). Radioactive isotopes are commonly used to make DNA probes and metabolic tracers.

Joining (J) segment
A small DNA segment that links genes to yield a functional gene encoding an immunogobulin.

Kanamycin
An antibiotic of the aminoglycoside family that poisons translation by binding to the ribosomes.

kanr
Kanamycin resistance gene. (See Selectable marker.)

Karyotype
All of the chromosomes in a cell or an individual organism, visible through a microsope during cell division.

Lag phase
The initial growth phase, during which cell number remains relatively constant prior to rapid growth. See growth phase.

Lawn
A uniform and uninterrupted laver of bacterial growth, in which individual colonies cannot be observed.

Legume
A member of the pea family that possesses root nodules containing nitrogen-fixing bacteria.

Library
A collection of cells, usually bacteria or yeast, that have been transformed with recombinant vectors carrying DNA inserts from a single species. (See cDNA library, Expression library, Genomic library.)

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' phosphate of adjacent nucleotides.

Ligate
The process of joining two or more DNA fragments.

Lineage
A chart that traces the flow of genetic information from generation to generation.

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 chromosome.

Linkage map
See Genetic linkage map.

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.

Liposomes
Membrane-bound vesicles constructed in the laboratory to transport biological molecules.

Locus (plural = loci)
A specific location or site on a chromosome.

Log phase
See Logarithmic phase.

Lysis
The destruction of the cell membrane.

Lysogen
A bacterial cell whose chromosome contains in- tegrated viral DNA

Lysogenic
A type or phase of the virus life cycle during which the virus integrates into the host chromosome of the infected cell, often remaining essentially dormant for some period of time. See Lysogen.

Lytic
A phase of the virus life cycle during which the vi- rus replicates within the host cell, releasing a new generation of viruses when the infected cell lyses.

Malignant
Having the properties of cancerous growth.

Mapping
Determining the physical location of a gene or genetic marker on a chromosome. (See Continuous map, Genetic map, Physical map.)

Megabase cloning
The cloning of very large DNA fragments. (See Cloning.)

Meiosis
The reduction division process by which haploid gametes and spores are formed, consisting of a single duplication of the genetic material followed by two mitotic divisions.

Messenger RNA (mRNA)
The class of RNA molecules that copies the genetic information from DNA, in the nucleus, and carries it to ribosomes, in the cytoplasm, where it is translated into protein. (See RNA.)

Metabolism
The biochemical processes that sustain a living cell or organism.

Metallothionein
A protective protein that binds heavy metals, such as cadmium and lead.

Microbe
A microorganism.

Microbial mats (biofilms)
Layered groups or communities of microbial populations.

Microinjection
A means to introduce a solution of DNA, protein, or other soluble material into a cell using a fine microcapillary pipet.

Mitosis
The replication of a cell to form two daughter cells with identical sets of chromosomes.

Molecular biology
The study of the biochemical and mo- lecular interactions within living cells.

Molecular cloning
The biological amplification of a specific DNA sequence through mitotic division of a host cell into which it has been transformed or transfected. (See Cloning.)

Molecular genetics
The study of the flow and regulation of genetic information between DNA, RNA, and protein molecules.

Monoclonal antibodies
Immunoglobulin molecules of single- epitope specificity that are secreted by a clone of B cells.

Monoculture
The agricultural practice of cultivating crops consisting of genetically similar organisms.

Monogenic
Controlled by or associated with a single gene.

Movable genetic element
(See Transposon.)

mRNA
See Messenger RNA.

Multi-locus probe
A probe that hybridizes to a number of different sites in the genome of an organism. (See Probe.)

Mutagen
Any agent or process that can cause mutations. See Mutation.

Mutation
An alteration in DNA structure or sequence of a gene. (See Point mutation.)

Mutualism
See Symbiosis.

Mycorrhizae
Fungi that form symbiotic relationships with roots of more developed plants.

National Science Foundation (NSF)
A nonregulatory agency which has oversight of biotechnology research activities that the agency funds.

Natural selection
The differential survival and reproduc- tion of organisms with genetic characteristics that enable them to better utilize environmental resources.

Nick translation
A procedure for making a DNA probe in which a DNA fragment is treated with DNase to produce single-stranded nicks, followed by incorporation of radioactive nucleotides from the nicked sites by DNA polymerase I.

Nicked circle (relaxed circle)
During extraction of plasmid DNA from the bacterial cell, one strand of the DNA becomes nicked. This relaxes the torsional strain needed to maintain supercoiling, producing the familiar form of plasmid. (See Plasmid.)

NIH
See National Institutes of Health.

Nitrocellulose
A membrane used to immobilize DNA, RNA, or protein, which can then be probed with a labeled sequence or antibody.

Nitrogen fixation
The conversion of atmospheric nitrogen to biologically usable nitrates.

Nitrogenous bases
The purines (adenine and guanine) and pyrimidines (thymine, cytosine, and uracil) that comprise DNA and RNA molecules.

Nodule
The enlargement or swelling on roots of nitrogen- fixing plants. The nodules contain symbiotic nitrogen- fixing bacteria. See Nitrogen fixation.

Nontarget organism
An organism which is affected by an interaction for which it was not the intended recipient.

Northern blotting
See Northern hybridization.

Northern hybridization
(Northern blotting). A procedure in which RNA fragments are transferred from an agarose gel to a nitrocellulose filter, where the RNA is then hybridized to a radioactive probe. (See Hybridization.)

NSF
See National Science Foundation.

Nuclease
A class of enzymes that degrades DNA and/or RNA molecules by cleaving the phosphodiester bonds that link adjacent nucleotides. In deoxyribonuclease (DNase), the substrate is DNA. In endonuclease, it cleaves at internal sites in the substrate molecule. Exonuclease progressively cleaves from the end of the substrate molecule. In ribonuclease (RNase), the substrate is RNA. In the S1 nuclease, the substrate is single-stranded DNA or RNA.

Nucleic acids
The two nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are made up of long chains of molecules called nucleotides. See DNA, RNA, Nucleotides.

Nuclein
The term used by Friedrich Miescher to describe the nuclear material he discovered in 1869, which today is known as DNA.

Nucleoside
A building block of DNA and RNA, consisting of a nitrogenous base linked to a five carbon sugar. (See Nucleoside analog.)

Nucleoside analog
A synthetic molecule that resembles a naturally occuring nucleoside, but that lacks a bond site needed to link it to an adjacent nucleotide. (See Nucleoside.)

Nucleotide
A building block of DNA and RNA, consisting of a nitrogenous base, a five-carbon sugar, and a phosphate group. Together, the nucleotides form codons, which when strung together form genes, which in turn link to form chromosomes. (See Chromosome, Codon, Complementary nucleotides, Dideoxynucleotide, DNA, Gene, Oligonucleotide, RNA.)

Nucleus
The membrane-bound region of a eukaryotic cell that contains the chromosomes.

Occupational Safety and Health Act
See Occupational Safety and Health Administration.

Oligonucleotide
A DNA polymer composed of only a few nucleotides. (See Nucleotide.)

Oncogene
A gene that contributes to cancer formation when mutated or inappropriately expressed. (See Cellular oncogene, Dominant oncogene, Immortalizing oncogene, Recessive oncogene.)

Oncogenesis
The progression of cytological, genetic, and cellular changes that culminate in a malignant tumor.

Open pollination
Pollination by wind, insects, or other natural mechanisms.

Open reading frame
A long DNA sequence that is unin- terrupted by a stop codon and encodes part or all of a protein. (See Reading frame.)

Operator
A prokaryotic regulatory element that interacts with a repressor to control the transcription of adjacent structural genes.

Organelle
A cell structure that carries out a specialized function in the life of a cell.

Origin of replication
The nucleotide sequence at which DNA synthesis is initiated.

OSHA
See Occupational Safety and Health Administration.

Overlapping reading frames
Start codons in different reading frames generate different polypeptides from the same DNA sequence. (See Reading frame.)

Ovum
A female gamete.

Paleontology
The study of the fossil record of past geo- logical periods and of the phylogenetic relationships between ancient and contemporary plant and animal species.

Palindrome
See Palindromic sequence.

Palindromic sequence
A DNA locus whose 5'-to-3' sequence is identical on each DNA strand. The sequence is the same when one strand is read left to right and the other strand is read right to left. Recognition sites of many restriction enzymes are palindromic. See DNA.

pAMP
Ampicillin-resistant plasmid developed for this laboratory course. (See Plasmid.)

Parasitism
The closee association of two or more dissimilar organisms where the association is harmful to at least one. See Commensalism, Parasitism, Symbiosis.

Pathogen
Organism which can cause disease in another organism.

pBR322
A derivation of ColE1, one of the first plasmid vectors widely used. (See Plasmid.)

PCR
See Polymerase chain reaction.

Pedigree
A diagram mapping the genetic history of a par- ticular family.

Persistence
Ability of an organism to remain in a particular setting for a period of time after it is introduced.

Pesticide
A substance that kills harmful organisms (for example, an insecticide or fungicide).

Phage (particle)
See Bacteriophage.

Phenotype
The observable characteristics of an organism, the expression of gene alleles (genotype) as an observable physical or biochemical trait. See Genotype.

Pheromone
A hormone-like substance that is secreted into the environment.

Phosphatase
An enzyme that hydrolyzes esters of phosphoric acid, removing a phosphate group.

Phosphodiester bond
A bond in which a phosphate group joins adjacent carbons through ester linkages. A condensation reaction between adjacent nucleotides results in a phosphodiester bond between 3' and 5' carbons in DNA and RNA.

Phospholipid
A class of lipid molecules in which a phos- phate group is linked to glycerol and two fatty acyl groups. A chief component of biological membranes. (See Inositol phospholipid.)