{"thcode":2,"term":{"code":89,"name":"biochemistry","parent":650,"scope":"Study of chemical processes that occur within or are mediated by living organisms."},"uf":[{"name":"biogeochemistry","usewith":false},{"name":"chemistry (life sciences)","usewith":false},{"name":"environmental chemistry","usewith":false}],"bt":[{"code":650,"name":"life sciences","parent":1019,"scope":"Branches of science that study living and fossil organisms."},{"code":1019,"name":"sciences","parent":1,"scope":"Major educational fields, fields of study, and professional groupings within USGS."},{"code":1,"name":"Categories","parent":null,"scope":"Thematic terms for categorizing information resources.  This thesaurus is intended to support finding and understanding scientific information."}],"nt":[],"rt":[{"code":276,"name":"DNA sequencing","parent":153,"scope":"Biochemical procedure to determine the order of nucleotides in genes."},{"code":69,"name":"atomic absorption analysis","parent":153,"scope":"Technique used to identify chemicals based on the measurement of the spectra produced by atoms and molecules with absorption of electromagnetic radiation."},{"code":2288,"name":"bioenergetics","parent":1347,"scope":"Processes by which a living organism acquires, produces, utilizes, or transforms energy. "},{"code":93,"name":"biogeochemical cycling","parent":310,"scope":"The cycling of chemical constituents through a biological system."},{"code":2299,"name":"biomarkers","parent":317,"scope":"Biochemical, physiological, morphological, or histopathological characteristics of organisms that signify exposure to contaminants.  Also used for biogeochemical measurements of rocks to detect biological origin."},{"code":141,"name":"carbon cycling","parent":93,"scope":"The circulation of carbon in the biosphere, atmosphere, and hydrosphere through a series of processes that include photosynthesis, consumption, and respiration."},{"code":142,"name":"carbon isotope analysis","parent":654,"scope":"Experimental determination of the proportion of a given stable carbon isotope (C12 or C13) in a sample."},{"code":153,"name":"chemical analysis","parent":619,"scope":"Chemical techniques used to identify the composition of substances."},{"code":158,"name":"chromatography","parent":153,"scope":"Analytical techniques used to separate or partition the components of a gaseous or liquid mixture by differences in absorption rates during flow around or over surface absorbents such as columns of silica, filter papers, or gels."},{"code":328,"name":"electrophoresis","parent":153,"scope":"Analytical technique to separate and identify components in a mixture using the differential migration of molecules based on their net charge through a paper or gel medium."},{"code":400,"name":"flow cytometry","parent":153,"scope":"Laboratory technique to determine the amount of DNA in cells tagged by fluorescent dye by measuring the intensity of fluorescence under a laser beam."},{"code":407,"name":"food web","parent":807,"scope":"The complex intertwining of the interrelated food chains in an ecosystem."},{"code":426,"name":"gas chromatography","parent":158,"scope":"Chromatographic technique used to separate or partition the components of a mixture.  Solid and liquid samples are vaporized and passed through a column containing a liquid that differentially absorbs the  molecules."},{"code":609,"name":"isotopic analysis","parent":619,"scope":"Experimental determination of the proportion of a given isotope (or isotopes) in a sample."},{"code":654,"name":"light stable isotope analysis","parent":609,"scope":"Analytical technique using mass spectrometry to measure the different isotopic forms of low mass (light) elements such as oxygen, hydrogen, carbon, nitrogen and sulfur that occur in samples."},{"code":662,"name":"liquid chromatography","parent":158,"scope":"Chromatographic technique to separate or partition the components of a mixture in which samples are liquid and passed through a column."},{"code":711,"name":"mass spectroscopy","parent":153,"scope":"Instrumental technique to separate and identify molecules.  Gaseous ions are formed, with or without fragmentation.  Their mass\/charge ratios and relative electrical abundance are then measured or the spectra are recorded."},{"code":720,"name":"mercury contamination","parent":1181,"scope":"Biological disturbances caused by mercury compounds that have entered the environment."},{"code":783,"name":"neutron activation analysis","parent":153,"scope":"Sensitive laboratory technique for both qualitative and quantitative analysis of elements in samples.  Target nuclei are bombarded with neutron beams to start nuclear reactions which emit characteristic gamma ray radiations."},{"code":807,"name":"nutrient cycling","parent":93,"scope":"The exchange of elements or compounds essential for the nourishment of organisms in an ecosystem."},{"code":855,"name":"oxygen isotope analysis","parent":654,"scope":"Experimental determination of the proportion of a given stable oxygen isotope in a sample."},{"code":872,"name":"particle-beam spectroscopy","parent":153,"scope":"Analytical technique using a concentrated beam of charged subatomic particles."},{"code":879,"name":"pesticide and herbicide contamination","parent":769,"scope":"Pollution resulting from chemical agents applied to crops, rights of way, lawns, or residences to control weeds, insects, fungi, nematodes, rodents or other pests (pesticides) or kill undesirable plants (herbicides)."},{"code":919,"name":"polymerase chain reaction","parent":153,"scope":"Biochemical technique that uses enzymes to replicate new nucleotides of DNA from DNA triphosphates using DNA as a template."},{"code":1191,"name":"tritium analysis","parent":654,"scope":"Mass spectrometric measurement of the decay of the radioactive isotope of hydrogen in water samples as a means of dating and investigating changes in water."}]}