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Filebox - Biotechnology Dictionary Category: Earth and Environment > Biotechnology Date & country: 13/09/2007, USA Words: 455

Abiotic stress
Outside (nonliving) factors which can cause harmful effects to plants, such as soil conditions, drought, extreme temperatures.

Abzyme
See Catalytic antibody.

Adaptive radiation
The evolution of new species or sub- species to fill unoccupied ecological niches.

Aerobe
A microorganism that grows in the presence of oxygen. See Anaerobe.

Agarose gel electrophoresis
A matrix composed of a highly purified form of agar that is used to separate larger DNA and RNA molecules ranging 20,000 nucleotides. (See Electrophoresis.)

Alleles
Alternate forms of a gene or DNA sequence, which occur on either of two homologous chromosomes in a diploid organism. (See DNA polymorphism.)

Alternative mRNA splicing
The inclusion or exclusion of different exons to form different mRNA transcripts. (See RNA.)

Amino acid
Any of 20 basic building blocks of proteins-- composed of a free amino (NH2) end, a free carboxyl (COOH) end, and a side group (R).

Ampicillin (beta-lactamase)
An antibiotic derived from penicillin that prevents bacterial growth by interfering with cell wall synthesis.

Amplify
To increase the number of copies of a DNA sequence, in vivo by inserting into a cloning vector that replicates within a host cell, or in vitro by polymerase chain reaction (PCR).

Anaerobe
An organism that grows in the absence of oxygen. See Aerobe.

Anneal
The pairing of complementary DNA or RNA sequences, via hydrogen bonding, to form a double-stranded polynucleotide. Most often used to describe the binding of a short primer or probe.

Anti-oncogene
See Recessive oncogene.

Antibiotic
A class of natural and synthetic compounds that inhibit the growth of or kill other microorganisms. (See Antibiotic resistance, Bacteriocide, Bacteriostat.)

Antibiotic resistance
The ability of a microorganism to produce a protein that disables an antibiotic or prevents transport of the antibiotic into the cell.

Antibody
An immunoglobulin protein produced by B- lymphocytes of the immune system that binds to a specific antigen molecule. (See monoclonal antibodies, polyclonal antibodies.)

Anticodon
A nucleotide base triplet in a transfer RNA molecule that pairs with a complementary base triplet, or codon, in a messenger RNA molecule. See Codon, Messenger RNA, RNA.

Antigen
Any foreign substance, such as a virus, bacterium, or protein, that elicits an immune response by stimulating the production of antibodies. (See Antigenic determinant, antigenic switching.)

Antigenic determinant
A surface feature of a microorganism or macromolecule, such as a glycoprotein, that elicits an immune response.

Antigenic switching
The altering of a microorganism's surface antigens through genetic rearrangement, to elude detection by the host's immune system.

Antimicrobial agent
Any chemical or biological agent that harms the growth of microorganisms.

Antisense RNA
A complementary RNA sequence that binds to a naturally occurring (sense) mRNA molecule, thus blocking its translation. (See RNA.)

Asexual reproduction
Nonsexual means of reproduction which can include grafting and budding.

Autosome
A chromosome that is not involved in sex determination.

Bacillus
A rod-shaped bacterium.

Bacillus thuringiensis (Bt)
A bacterium that kills insects; a major component of the microbial pesticide industry.

Backcross
Crossing an organism with one of its parent organisms.

Bacteriocide
A class of antibiotics that kills bacterial cells.

Bacteriostat
A class of antibiotics that prevents growth of bacterial cells.

Bacterium
A single-celled, microscopic prokaryotic organism: a single cell organism without a distinct nucleus.

Base pair (bp)
A pair of complementary nitrogenous bases in a DNA molecule--adenine-thymine and guanine-cytosine. Also, the unit of measurement for DNA sequences.

beta-DNA
The normal form of DNA found in biological systems, which exists as a right-handed helix.

beta-Lactamase
Ampicillin resistance gene. (See Selectable marker.)

Bioaugmentation
Increasing the activity of bacteria that decompose pollutants; a technique used in bioremediation.

Biodiversity
The wide diversity and interrelatedness of earth organisms based on genetic and environmental factors.

Bioenrichment
Adding nutrients or oxygen to increase microbial breakdown of pollutants.

Biofilms
See Microbial mats.

Biologics
Agents, such as vaccines, that give immunity to diseases or harmful biotic stresses.

Biomass
The total dry weight of all organisms in a particular sample, population, or area.

Bioremediation
The use of microorganisms to remedy environmental problems. See Bioaugmentation, Bioenrichment.

Biotechnology
The scientific manipulation of living organ- isms, especially at the molecular genetic level, to produce useful products. Gene splicing and use of recombinant DNA (rDNA) are major techniques used.

Biotic stress
Living organisms which can harm plants , such as viruses, fungi, and bacteria, and harmful insects. See Abiotic stress.

bP
See Base pair.

Bt
See Bacillus thuringiensis.

Capsid
See Coat protein.

Carcinogen
A substance that induces cancer.

Carcinoma
A malignant tumor derived from epithelial tissue, which forms the skin and outer cell layers of internal organs.

Catalyst
A substance that promotes a chemical reaction by lowering the activation energy of a chemical reaction, but which itself remains unaltered at the end of the reaction. (See Catalytic antibody, Catalytic RNA.)

Catalytic antibody (abzyme)
An antibody selected for its ability to catalyze a chemical reaction by binding to and stabilizing the transition state intermediate.

Catalytic RNA (ribozyme)
A natural or synthetic RNA molecule that cuts an RNA substrate.

Cation
A positively charged ion.

cDNA
DNA synthesized from an RNA template using reverse transcriptase.

cDNA library
A library composed of complementary copies of cellular mRNAs. (See Library.)

Cellular oncogene (proto-oncogene)
A normal gene that when mutated or improperly expressed contributes to the development of cancer. (See Oncogene.)

Centers of origin
Usually the location in the world where the oldest cultivation of a particular crop has been identified.

Central dogma
Francis Crick's seminal concept that in nature genetic information generally flows from DNA to RNA to protein.

Centrifugation
Separating molecules by size or density using centrifugal forces generated by a spinning rotor. G forces of several hundred thousand times gravity are generated in ultracentrifugation. (See Density gradient centrifugation.)

Centromere
The central portion of the chromosome to which the spindle fibers attach during mitotic and meiotic division.

Chemotherapy
A treatment for cancers that involves ad- ministering chemicals toxic to malignant cells.

Chloramphenicol
An antibiotic that interferes with protein synthesis.

Chromatid
Each of the two daughter strands of a duplicated chromosome joined at the centromere during mitosis and meiosis.

Chromosome
A single DNA molecule, a tightly coiled strant of DNA, condensed into a compact structure in vivo by complexing with accessory histones or histone-like proteins. Chromosomes exist in pairs in higher eukaryotes. (See Chromosome walking.)

Chromosome walking
Working from a flanking DNA marker, overlapping clones are successively identified that span a chromosomal region of interest. (See Chromosome.)

Cistron
A DNA sequence that codes for a specific polypeptide; a gene. See DNA, Gene.

Clone
An exact genetic replica of a specific gene or an entire organism. See Cloning.

Cloning
The mitotic division of a progenitor cell to give rise to a population of identical daughter cells or clones. (See Directional cloning, Megabase cloning, Molecular cloning, Subcloning.)

Coat protein (capsid)
The coating of a protein that enclosed the nucleic acid core of a virus.

Codon
A group of three nucleotides that specifies addition of one of the 20 amino acids during translation of an mRNA into a polypeptide. Strings of codons form genes and strings of genes form chromosomes. (See Initiation codon, Termination codon.)

Coenzyme (cofactor)
An organic molecule, such as a vitamin, that binds to an enzyme and is required for its catalytic activity.

Cofactor
See Coenzyme.

Colony
A group of identical cells (clones) derived from a single progenitor cell.

Commensalism
The close association of two or more dissimilar organisms where the association is advantageous to one and doesn't affect the other(s). See Parasitism, Symbiosis.

Competency
An ephemeral state, induced by treatment with cold cations, during which bacterial cells are capable of uptaking foreign DNA.

Complementary DNA or RNA
The matching strand of a DNA or RNA molecule to which its bases pair. (See DNA, RNA.)

Complementary nucleotides
Members of the pairs adenine-thymine, adenine-uracil, and guaninecytosine that have the ability to hydrogen bond to one another. (See nucleotide.)

Concatemer
A DNA segment composed of repeated sequences linked end to end.

Conjugation
The joining of two bacteria cells when genetic material is transferred from one bacterium to another.

Constitutive promoter
An unregulated promoter that allows for continual transcription of its associated gene. (See Promoter.)

Contiguous (contig) map
The alignment of sequence data from large, adjacent regions of the genome to produce a continuous nucleotide sequence across a chromosomal region. (See Mapping.)

Copy DNA
See cDNA.

Cross-hybridization
The hydrogen bonding of a single- stranded DNA sequence that is partially but not entirely complementary to a singlestranded substrate. Often, this involves hybridizing a DNA probe for a specific DNA sequence to the homologous sequences of different species.

Cross-pollination
Fertilization of a plant from a plant with a different genetic makeup.

Crossing-over
The exchange of DNA sequences between chromatids of homologous chromosomes during meiosis.

Culture
A particular kind of organism growing in a laboratory medium.

Cytogenetics
Study that relates the appearance and behavior of chromosomes to genetic phenomenon.

Dalton
A unit of measurement equal to the mass of a hydrogen atom, 1.67 x 10E-24 gram/L (Avogadro's number).

Death phase
The final growth phase, during which nutrients have been depleted and cell number decreases. (See Growth phase).

Denature
To induce structural alterations that disrupt the biological activity of a molecule. Often refers to breaking hydrogen bonds between base pairs in double-stranded nucleic acid molecules to produce in single-stranded polynucleotides or altering the secondary and tertiary structure of a protein, destroying its activity.

Density gradient centrifugation
High-speed centrifugation in which molecules 'float' at a point where their density equals that in a gradient of cesium chloride or sucrose. (See Centrifugation.)

Deoxyribonucleic acid
See DNA, nuclease.

Diabetes
A disease associated with the absence or reduced levels of insulin, a hormone essential for the transport of glucose to cells.

Dideoxynucleotide (didN)
A deoxynucleotide that lacks a 3' hydroxyl group, and is thus unable to form a 3'-5' phosphodiester bond necessary for chain elongation. Dideoxynucleotides are used in DNA sequencing and the treatment of viral diseases. (See Nucleotide.)

didN
See Dideoxynucleotide.

Digest
To cut DNA molecules with one or more restriction endonucleases.

Diploid cell
A cell which contains two copies of each chromosome. See Haploid cell.

Directional cloning
DNA insert and vector molecules are digested with two different restriction enzymes to create noncomplementary sticky ends at either end of each restriction fragment. This allows the insert to be ligated to the vector in a specific orientation and prevents the vector from recircularizing. (See Cloning.)

DNA (Deoxyribonucleic acid)
An organic acid and polymer composed of four nitrogenous bases--adenine, thymine, cytosine, and guanine linked via intervening units of phosphate and the pentose sugar deoxyribose. DNA is the genetic material of most organisms and usually exists as a double-stranded molecule in which two antiparallel strands are held together by hydrogen bonds between adeninethymine and cytosine-guanine. (See b-DNA, cDNA, Complementary DNA or RNA, DNA polymorphism, DNA sequencing, Double-stranded complementary D…

DNA diagnosis
The use of DNA polymorphisms to detect the presence of a disease gene.

DNA fingerprint
The unique pattern of DNA fragments identified by Southern hybridization (using a probe that binds to a polymorphic region of DNA) or by polymerase chain reaction (using primers flanking the polymorphic region).

DNA ligase
See Ligase.