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| Abiotic stress |
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Outside (nonliving) factors which can cause harmful effects to plants, such as soil conditions, drought, extreme temperatures.
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| Abzyme |
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See Catalytic antibody.
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| Adaptive radiation |
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The evolution of new species or sub- species to fill unoccupied ecological niches.
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| Aerobe |
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A microorganism that grows in the presence of oxygen. See Anaerobe.
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| Agarose gel electrophore |
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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.)
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| Alternative mRNA splicin |
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The inclusion or exclusion of different exons to form different mRNA transcripts. (See RNA.)
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| Amino acid |
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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).
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| Ampicillin (beta-lactamas |
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An antibiotic derived from penicillin that prevents bacterial growth by interfering with cell wall synthesis.
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| Amplify |
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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).
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| Anaerobe |
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An organism that grows in the absence of oxygen. See Aerobe.
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| Anneal |
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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.
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| Antibiotic |
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A class of natural and synthetic compounds that inhibit the growth of or kill other microorganisms. (See Antibiotic resistance, Bacteriocide, Bacteriostat.)
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| Antibiotic resistance |
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The ability of a microorganism to produce a protein that disables an antibiotic or prevents transport of the antibiotic into the cell.
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| Antibody |
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An immunoglobulin protein produced by B- lymphocytes of the immune system that binds to a specific antigen molecule. (See monoclonal antibodies, polyclonal antibodies.)
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| Anticodon |
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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.
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| Antigen |
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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.)
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| Antigenic determinant |
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A surface feature of a microorganism or macromolecule, such as a glycoprotein, that elicits an immune response.
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| Antigenic switching |
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The altering of a microorganism's surface antigens through genetic rearrangement, to elude detection by the host's immune system.
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| Antimicrobial agent |
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Any chemical or biological agent that harms the growth of microorganisms.
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| Anti-oncogene |
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See Recessive oncogene.
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| Antisense RNA |
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A complementary RNA sequence that binds to a naturally occurring (sense) mRNA molecule, thus blocking its translation. (See RNA.)
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| Asexual reproduction |
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Nonsexual means of reproduction which can include grafting and budding.
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| Autosome |
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A chromosome that is not involved in sex determination.
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| Bacillus |
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A rod-shaped bacterium.
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| Bacillus thuringiensis (B |
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A bacterium that kills insects; a major component of the microbial pesticide industry.
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| Backcross |
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Crossing an organism with one of its parent organisms.
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| Bacteriocide |
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A class of antibiotics that kills bacterial cells.
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| Bacteriophage (phage or p |
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A virus that in- fects bacteria. Altered forms are used as vectors for cloning DNA.
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| Bacteriostat |
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A class of antibiotics that prevents growth of bacterial cells.
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| Bacterium |
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A single-celled, microscopic prokaryotic organism: a single cell organism without a distinct nucleus.
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| Base pair (bp). |
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A pair of complementary nitrogenous bases in a DNA molecule--adenine-thymine and guanine-cytosine. Also, the unit of measurement for DNA sequences.
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| beta-DNA |
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The normal form of DNA found in biological systems, which exists as a right-handed helix.
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| beta-Lactamase |
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Ampicillin resistance gene. (See Selectable marker.)
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| Bioaugmentation |
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Increasing the activity of bacteria that decompose pollutants; a technique used in bioremediation.
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| Biodiversity |
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The wide diversity and interrelatedness of earth organisms based on genetic and environmental factors.
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| Bioenrichment |
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Adding nutrients or oxygen to increase microbial breakdown of pollutants.
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| Biofilms |
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See Microbial mats.
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| Biologics |
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Agents, such as vaccines, that give immunity to diseases or harmful biotic stresses.
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| Biomass |
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The total dry weight of all organisms in a particular sample, population, or area.
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| Bioremediation |
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The use of microorganisms to remedy environmental problems. See Bioaugmentation, Bioenrichment.
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| Biotechnology |
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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.
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| Biotic stress |
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Living organisms which can harm plants , such as viruses, fungi, and bacteria, and harmful insects. See Abiotic stress.
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| Bt |
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See Bacillus thuringiensis.
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| Carcinogen |
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A substance that induces cancer.
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| Carcinoma |
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A malignant tumor derived from epithelial tissue, which forms the skin and outer cell layers of internal organs.
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| Catalyst |
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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.)
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| Catalytic antibody (abzym |
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An antibody selected for its ability to catalyze a chemical reaction by binding to and stabilizing the transition state intermediate.
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| Catalytic RNA (ribozyme). |
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A natural or synthetic RNA molecule that cuts an RNA substrate.
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