Calspace Courses

 Climate Change · Part One
 Climate Change · Part Two
 Introduction to Astronomy
 Life in the Universe

 Glossary: Climate Change
 Glossary: Astronomy
 Glossary: Life in Universe

    Glossary of Terms - S to Z
    Index: A to F | G to L | M to R | S to Z

    scientific law - (n.)

    A summary of experimental data; often expressed in the form of a mathematical equation.

    scientific model - (n.)

    A representation that serves to explain a scientific phenomenon.

    secondary structure - (n.)

    Arrangement of polypeptide chains in a protein—e.g., helix or pleated sheet.

    sediment - (n.)

    Particulate, commonly granular mineralic material deposited by water, wind, or glaciers that on compression can be lithified to a sedimentary rock.

    sedimentary rock - (n.)

    A rock formed by the deposition and hardening of layers of sediment, usually either underwater or in an area subject to flooding.

    seed - (n.)

    A structure containing a plant embryo, together with nutritive material, within a protective hull : Seeds are naked in gymnosperms and embedded in a fruit in angiosperms. ~ See Also: Angiosperms, Fruit, Gymnosperms.

    sequencing - (n.)

    The determination of the sequence of nucleotides in nucleic acids and of amino acids in proteins. ~ See Also: Nucleic acid, Protein.

    sessile - (n.)

    attached directly by the base (rather than being raised on a stalk).

    SETI - (n.)

    Search for Extra-Terrestrial Intelligence.

    shale - (n.)

    A sedimentary rock formed by consolidation of clay or mud.

    Index: A to F | G to L | M to R | S to Z

    shock wave - (n.)

    discontinuity in the flow of a fluid (including a gas or plasma) marked by an abrupt increase in pressure, temperature, and flow velocity at the shock front.

    siltstone - (n.)

    A sedimentary rock formed by consolidation of fine silt.

    solute - (n.)

    The substance that is dissolved in another substance (solvent) to form a solution; usually present in a smaller amount than the solvent.

    solution - (n.)

    A homogeneous mixture of two or more substances.

    solvent - (n.)

    The substance that dissolves another substance (solute) to form a solution; usually present in a larger amount than the solute.

    species - (n.)

    The fundamental category of biological classification, ranking below the genus and in some species composed of subspecies or varieties; of various definitions, the most common is the "Biological Species Concept" "Species are actually or potentially interbreeding natural populations which are reproductively isolated from other such groups."

    specific heat (of a substance) - (n.)

    The amount of heat required to raise the temperature of 1 g of the substance by 1 °C.

    spectrum - (n.)

    (pl. spectra) An arrangement of electromagnetic radiation according to wavelength.

    sperm cell - (n.)

    The male gamete. ~ See Also: Egg cell : Fertilization, Gamete, Sexual reproduction.

    spirochete - (n.)

    A small spiral-shaped bacterium. Spirochetes are the cause of human disease such as syphilis and yaws, and their harmless relatives are common denizens of the soil. It was thought that ancestors of spirochetes might have contributed to eukaryotic cells through symbiosis, but this is not proven.

    Index: A to F | G to L | M to R | S to Z

    split genes - (n.)

    Genes made of two or more exons—parts that are expressed—separated by introns—parts that are not expressed. ~ See Also: Exon, Intron, RNA splicing.

    spore - (n.)

    A protected, dormant form of a prokaryotic or eukaryotic microorganism : In plants, a protected, haploid germ cell that develops, when conditions are favorable, into a gamete-generating structure or organism. ~ See Also: Alternation of generations, Diploid, Gamete, Haploid.

    spore plant - (n.)

    Any of various "lower land plants" that instead of producing seeds (as do gymnosperms and angiosperms) reproduce by shedding spores, such as club mosses (lycophytes) and horse tails (sphenophytes).

    stomata - (n.)

    Openings in leaves that allow absorption of carbon dioxide and release of oxygen.

    STP - (n.)

    Standard temperature (0 °C) and pressure (1 atm).

    strategies of life - (n.)

    Autotrophy and heterotrophy, strategies evolved to meet the necessities of life.

    stratosphere - (n.)

    One of the upper layers of the atmosphere of a planet, above the weather. The earth's stratosphere ranges from about 20 to 50 km in altitude.

    stratum - (n.)

    A layer or horizon of sedimentary rock.

    Strecker synthesis - (n.)

    A chemical reaction series by which amino acids are formed from aldehyde, hydrogen cyanide, and ammonium.

    stromatolite - (n.)

    A geological feature formed by the conversion of loose, unconsolidated sediment into a coherent layer, as a result of the growth, movement, or activity of microorganisms; e.g., blue-green algae. Microfossils associated with stromatolite formation are an important form of evidence for early life on Earth, and thus a search for stromatolites could be undertaken on other planets in sites where liquid water might have accumulated.

    Index: A to F | G to L | M to R | S to Z

    subduction - (n.)

    The process in which one tectonic plate is submerged below another along a line where two plates collide. A subduction zone is usually characterized by a deep trench and an adjoining mountain range.

    sublimation - (n.)

    process of passing from gas to solid state (or vice versa) without becoming a liquid.

    sugar - (n.)

    Any of various monosaccharides having the generalized formula CH2O, such as fructose, sucrose, and glucose.

    sulfate-reducing bacterium - (n.)

    Any of various chemoautotrophic bacteria that derive energy from reduction of sulfate (SO4 ~ such as Desulfovibrio.

    supergroup, geologic - (n.)

    A major category in the stratigraphic classification of rocks ranking above the group.

    superphylum - (n.)

    taxonomic category lying between a kingdom and a phylum.

    symbiosis - (n.)

    intimate living together of two organisms (called symbionts) of different species, for mutual or one-sided benefit.

    synergistic effect - (n.)

    An effect much greater than the sum of the expected effects.

    system, geologic - (n.)

    The term applied to the rocks of a specified geologic period; for example, rocks formed during the Cambrian Period comprise the Cambrian System.

    taxon - (n.)

    In biologic classification, pertaining to a unit of any rank (that is, a particular species, genus, family, class, order, or division or phylum) or the scientific name of that unit.

    Index: A to F | G to L | M to R | S to Z

    taxonomic occurrence - (n.)

    The number of taxa of a particular rank known to be present in named geologic units of a specified kind (for example, the number of species of a particular group reported from one or more geologic formations).

    tectonic - (n.)

    Pertaining to a crust-deforming process or event.

    tertiary structure - (n.)

    The folds, bends, and twists in protein or nucleic acid structure.

    theories - (n.)

    Detailed explanations of the behavior of matter based on experiments; may be revised if new data warrant.

    thermophile - (n.)

    Any of various organisms, such as diverse prokaryotes, that can survive and grow in relatively high-temperature environments such as hot springs.

    thymine - (n.)

    Or 5-methyl-uracil, a pyrimidine base found only in DNA. ~ See Also: Base pairing, Cytosine, Pyrimidines, Deoxyribonucleic acid, Uracil.

    transcription - (n.)

    The synthesis of RNA on a DNA template. ~ See Also: Base pairing, Reverse transcription.

    transfer RNA - (n.)

    An RNA molecule serving as transporter of a defined kind of amino acid in protein synthesis and bearing a triplet of bases, or anticodon, that, when the molecule is strategically situated on the ribosome surface, is specifically recognized by a messenger-RNA codon. ~ See Also: Anticodon, Base pairing, Codon, Messenger RNA, Protein, Ribosome, Wobble.

    translation - (n.)

    The process whereby the information written in the nucleotide sequence of a gene is expressed in the amino-acid sequence of the corresponding polypeptide or protein. ~ See Also: Genetic code, Polypeptide, Protein.

    tree of life - (n.)

    A branching, treelike representation showing the relatedness of all living organisms, commonly based on comparison of rRNAs, the ribonucleic acids of protein-manufacturing ribosomes.

    Index: A to F | G to L | M to R | S to Z

    triple bond - (n.)

    The sharing of three pairs of electrons between two atoms.

    uracil - (n.)

    A pyrimidine base found only in RNA : See Cytosine, Pyrimidines, Ribonucleic acid, Thymine.

    valence - (n.)

    The number of bonds that an atom can form.

    ventists - (n.)

    researchers who speculate that the synthesis of prebiotic compounds that were required for the origin of life, or even the origin of life itself, took place within deep ocean hydrothermal vents or in their vicinity.

    vertebrate - (n.)

    Any member of the subphylum Vertebrata that consists of all animals that possess a bony or cartilaginous skeleton and a well-developed brain, such as fishes, amphibians, reptiles, birds, and mammals.

    vesicle - (n.)

    In planktonic cyanobacteria and other prokaryotes, a gas-filled pocket used to control buoyancy.

    virus - (n.)

    An infectious particle consisting essentially of a protein-coated or membrane enveloped DNA or RNA genome that codes for the constituents of the virus : Some viruses contain additional components, and their genomes additional genes : RNA viruses, in particular, have to provide the replicase or reverse transcriptase needed for their replication : Viruses enter certain prokaryotic or eukaryotic cells and multiply within these cells with the help of the local metabolism and enzyme machinery, often causing injuries or death of the infected cells. ~ See Also: Replicase, Retrovirus, Reverse transcriptase.

    volatile - (n.)

    The property of being easily vaporized. Volatile elements stay in gaseous form except at very low temperatures; they did not condense into solid form during the formation of the solar system.

    weathering - (n.)

    The chemical and physical processes that disaggregate a rock into its component mineral grains or crystals.

    zircon - (n.)

    a silicate mineral, ZrSiO4, diamondlike in appearance, that contains silica silicon dioxide, and the element zirconium. Some zircons in meteorites contain material from the period before the Solar System formed.

    zygote - (n.)

    The diploid cell formed by fusion (syngamy) of two haploid gametes, the earliest formed cell of the embryo of animals or the spore producing generation of plants.

    Index: A to F | G to L | M to R | S to Z


back to top
© 2002 All Rights Reserved - University of California, San Diego