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| Monogenic |
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Controlled by or associated with a single gene.
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| Movable genetic element |
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(See Transposon.)
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| Multi-locus probe |
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A probe that hybridizes to a number of different sites in the genome of an organism. (See Probe.)
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| Mutagen |
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Any agent or process that can cause mutations. See Mutation.
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| Mutation |
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An alteration in DNA structure or sequence of a gene. (See Point mutation.)
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| Mycorrhizae |
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Fungi that form symbiotic relationships with roots of more developed plants.
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| National Institutions of |
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A nonregulatory agency which has oversight of research activities that the agency funds.
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| National Science Foundati |
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A nonregulatory agency which has oversight of biotechnology research activities that the agency funds.
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| Natural selection |
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The differential survival and reproduc- tion of organisms with genetic characteristics that enable them to better utilize environmental resources.
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| Nick translation |
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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.
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| Nicked circle (relaxed ci |
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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.)
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| NIH |
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See National Institutes of Health.
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| Nitrocellulose |
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A membrane used to immobilize DNA, RNA, or protein, which can then be probed with a labeled sequence or antibody.
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| Nitrogen fixation |
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The conversion of atmospheric nitrogen to biologically usable nitrates.
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| Nitrogenous bases |
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The purines (adenine and guanine) and pyrimidines (thymine, cytosine, and uracil) that comprise DNA and RNA molecules.
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| Nodule |
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The enlargement or swelling on roots of nitrogen- fixing plants. The nodules contain symbiotic nitrogen- fixing bacteria. See Nitrogen fixation.
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| Nontarget organism |
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An organism which is affected by an interaction for which it was not the intended recipient.
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| Northern blotting |
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See Northern hybridization.
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| Northern hybridization |
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(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.)
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| NSF |
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See National Science Foundation.
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| Nuclease |
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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.
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| Nucleic acids |
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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.
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| Nuclein |
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The term used by Friedrich Miescher to describe the nuclear material he discovered in 1869, which today is known as DNA.
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| Nucleoside |
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A building block of DNA and RNA, consisting of a nitrogenous base linked to a five carbon sugar. (See Nucleoside analog.)
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| Nucleoside analog |
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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.)
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| Nucleotide |
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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.)
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| Nucleus |
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The membrane-bound region of a eukaryotic cell that contains the chromosomes.
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| Occupational Safety and H |
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See Occupational Safety and Health Administration.
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| Oligonucleotide |
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A DNA polymer composed of only a few nucleotides. (See Nucleotide.)
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| Oncogene |
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A gene that contributes to cancer formation when mutated or inappropriately expressed. (See Cellular oncogene, Dominant oncogene, Immortalizing oncogene, Recessive oncogene.)
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| Oncogenesis |
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The progression of cytological, genetic, and cellular changes that culminate in a malignant tumor.
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| Open pollination |
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Pollination by wind, insects, or other natural mechanisms.
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| Open reading frame |
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A long DNA sequence that is unin- terrupted by a stop codon and encodes part or all of a protein. (See Reading frame.)
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| Operator |
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A prokaryotic regulatory element that interacts with a repressor to control the transcription of adjacent structural genes.
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| Organelle |
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A cell structure that carries out a specialized function in the life of a cell.
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| Origin of replication |
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The nucleotide sequence at which DNA synthesis is initiated.
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| OSHA |
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See Occupational Safety and Health Administration.
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| Overlapping reading frame |
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Start codons in different reading frames generate different polypeptides from the same DNA sequence. (See Reading frame.)
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| Paleontology |
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The study of the fossil record of past geo- logical periods and of the phylogenetic relationships between ancient and contemporary plant and animal species.
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| Palindrome |
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See Palindromic sequence.
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| Palindromic sequence |
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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.
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| pAMP |
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Ampicillin-resistant plasmid developed for this laboratory course. (See Plasmid.)
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| Parasitism |
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The closee association of two or more dissimilar organisms where the association is harmful to at least one. See Commensalism, Parasitism, Symbiosis.
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| Pathogen |
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Organism which can cause disease in another organism.
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| pBR322 |
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A derivation of ColE1, one of the first plasmid vectors widely used. (See Plasmid.)
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| PCR |
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See Polymerase chain reaction.
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| Pedigree |
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A diagram mapping the genetic history of a par- ticular family.
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