Extreme Enviroment Glossary

abscisic acid-a plant hormone absolute zero-the lowest temperature theoretically obtainable (-273°C)

Acanthocephala -a phylum of parasitic invertebrate animals acclimation-a physiological adjustment to a change in a physical factor induced in the laboratory acclimatisation-a physiological adjustment to a change in an environmental factor (in nature) acidophile-an organism that grows best at low pH acidotolerant-an organism that can tolerate low pH but which grows best at a higher pH actinomycetes-a group of bacteria noted for their filamentous and branching growth patterns adaptation-an evolutionary change by which an organism becomes better suited to its environment aerobic-an environment that contains, or an organism or process that requires, oxygen alga (plural: algae)-a photosynthetic, plant-like protist alkaliphile-an organism that grows best at high pH alkalitolerant-an organism that can tolerate high pH but which grows best at a lower pH ametabolic-no metabolism amino acids -organic compounds that form the building blocks of proteins amphiphilic-a molecule that has both hydrophilic and hydrophobic parts anabiosis -see cryptobiosis anaerobic -an environment that lacks oxygen, or an organism or process that requires the absence of oxygen angiosperm-a flowering plant anhydrobiosis - surviving a cessation of metabolism due to water loss animalcules - microscopic animals (archaic term)

annelids-a phylum of segmented worm-like invertebrate animals

(includes earthworms) anoxic-lacking oxygen anoxybiosis - surviving a cessation of metabolism due to the absence of oxygen

Antarctic Circumpolar Current -an ocean current that completely encircles Antarctica, isolating it from the oceans of the rest of the world

Antarctic Polar Front -the region of the Antarctic Ocean where the cold, nutrient-rich surface waters of the Antarctic sink beneath the warmer northern waters antifreeze-a substance that lowers the freezing point of an organism's body fluids antifreeze proteins-proteins that inhibit the growth of ice crystals by attaching to their surface arachnids -a group of arthropods that includes scorpions, spiders, mites, ticks, harvest-men and king crabs Archaea -microorganisms that are similar in size and appearance to bacteria but very different in their molecular organisation. They form the third domain of life (the others being Bacteria and Eukarya) arthropods -a phylum of invertebrate animals with a hard exoskeleton and jointed legs (includes insects, arachnids, crustaceans and millipedes)

assimilation-the incorporation of food and/or inorganic materials into the complex constituents of an organism astrobiology (or exobiology)-the branch of biology that deals with the possibility, and likely nature, of extraterrestrial life atmosphere (unit of measurement)-the average atmospheric pressure at sea level autotroph-an organism that is able to produce organic compounds from simple inorganic compounds bacterium (plural: bacteria)-a unicellular, prokaryotic microorganism that lacks an organised nucleus and organelles barophilic- see piezophilic barotolerant - see piezotolerant benthic-living at the bottom of a sea or lake biomass-the total mass of organisms in a given area bound water - see osmotically inactive water bryophyte (moss)-a small flowerless green plant that lacks true roots capacity adaptation-the ability to grow and reproduce under extreme environmental conditions carbohydrates -a group of organic compounds that occurs in living organisms (includes sugars, starch and cellulose) catalyst-a substance that increases the rate of a chemical reaction without itself undergoing any permanent change chaperones -see molecular chaperones chemotroph-an organism that is able to produce organic compounds from simple inorganic compounds by obtaining energy from the oxidation of inorganic substances chilling intolerance-the death of an organism from the effects of cold but before it freezes (prefreeze mortality) chironomids (midges)-a group of insects chlorophyll-the green pigment of plants and cyanobacteria that absorbs light and which provides the energy for photosynthesis chloroplasts -the organelles of algae and plant cells in which the processes of photosynthesis occur chorion - eggshell (particularly of fish and insect eggs) cloaca - the common opening of the digestive, urinary and reproductive systems in some animals cold coma - the activity of an organism ceasing at low temperatures cold hardening-the process by which an organism increases its cold tolerance cold shock-inactivity induced by cold cold tolerance-the ability to survive low temperatures collembola-see springtails colligative properties-properties that depend only on the concentration of a solute and not on its composition compatible solutes-a solute that does not adversely affect the workings of cells concentration-the relative amount of a substance contained within a particular volume of space, e.g. the amount of solute per unit volume of solution conformation-the three-dimensional shape of a molecule consumers -organisms that satisfy their requirements for organic molecules and energy by eating (or otherwise utilising the products of) autotrophs (or other consumers) convergent evolution-the independent evolution of similar characteristics in two groups of organisms as a result of similar selection pressures crustacean-a group of arthropod animals that includes shrimps, crabs, water fleas etc.

cryobiosis - surviving a cessation of metabolism due to low temperatures cryogenics -the production and application of low temperatures. Also refers to the freezing of human bodies in the hope of being able to revive them at some future date cryopreservation-the preservation of biological materials (such as food or human tissues) by freezing cryoprotectant-a substance that protects against the harmful effects of freezing cryptobiosis -surviving a cessation of metabolism cuticle-a protective layer covering the outside of a plant or invertebrate animal cyanobacteria-a group of photosynthetic bacteria cyst-a tough protective capsule which contains the resting stage of an organism cytoplasm-the contents of a cell, excluding the nucleus deciduous-a plant that sheds its leaves annually decomposers-organisms that get their food from dead organisms or their waste products dehydrins-proteins in plants that are induced by desiccation denaturation-a process by which a protein unravels and loses its natural conformation, destroying its biological activity detritus - dead organisms and other organic debris diapause-a period of suspended development diatoms - single-celled algae with a cell wall of silica diffusion-the spontaneous movement of a substance from a region of high concentration to one of low concentration DNA (deoxyribonucleic acid)-a self-replicating organic molecule found in nearly all organisms which is the main constituent of chromosomes and whose sequence of nucleotides carries the organism's genetic information domain-the highest taxonomic grouping of organisms. There are three domains: Bacteria, Archaea and Eukarya dormancy-a period during which the normal physiological processes of an organism are slowed down or suspended ecological niche -the sum total of the physical and biological characteristics that determine the place an organism occupies in an ecological community ectotherm -an organism that is dependent on external sources of heat

(usually the sun) enchytraeids-a group of annelid worms endolithic -living within rocks endoplasmic reticulum -an extensive network of membranes within the cytoplasm of eukaryotic cells endotherm -an organism that is able to generate heat internally entropy-a measure of the degree of randomness or disorder in a system enzyme-a protein that catalyses (increases the rate of) biological reactions

Eukarya-the domain of eukaryotic organisms (fungi, protists, plants and animals)

eukaryote -an organism which has a cell, or cells, where the genetic material is contained within a distinct membrane-bound nucleus and which has membrane-bound organelles evolution (Darwinian evolution)-the process by which organisms develop and diversify from organisms that precede them exobiology - see astrobiology extracellular-outside the cells of an organism extradural-outside the membrane that encloses the brain and spinal cord extreme biology-the study of extreme organisms and extreme environments extremophile-an organism that will grow and reproduce under extreme environmental conditions extremozymes -enzymes that operate under extreme conditions fatty acids -one of the subunits of lipids fern-a plant that lacks flowers and which reproduces by producing spores freeze avoiding-an organism that survives low temperature by preventing ice from forming within its body freeze concentration-the concentration of salts in the remaining unfrozen portion of a solution as a result of the sequestration of water molecules into ice freezing tolerant -an organism that survives ice forming within its body fungi (singular: fungus)-multicellular or unicellular eukaryotes that absorb their food across their cell walls after secreting enzymes onto it glycogen -the main carbohydrate store in animals glycoprotein -a protein with an attached carbohydrate group gymnosperms-plants that produce unprotected seeds (e.g. conifers) habitable zone-the zone around a star where planets capable of supporting life may be found haemoglobin -the red oxygen-transporting pigment of the blood haemolymph-the body fluid of arthropods (equivalent to the blood of vertebrates) halobacteria-salt-tolerant archaea halophile-an organism that grows best at high salt concentrations halotolerant-an organism that tolerates high salt concentrations but grows best at lower concentrations heat coma-the activity of an organism ceasing at high temperatures heat of crystallisation -see latent heat of crystallisation heat shock response-the induction of protective proteins, such as molecular chaperones, by a mild heat shock heterotroph-an organism that requires complex organic molecules

(usually obtained by feeding on other organisms) hibernation - spending the winter in a dormant state histones -a group of small proteins that are associated with DNA in chromosomes homeostasis -the maintenance of a constant environment within an organism by physiological mechanisms hydrophilic-water attracting hydrophobic -water repelling hydrothermal vent -an opening in the sea floor through which geother-

mally heated water flows hyperosmotic stress -an osmotic stress produced when a cell or organism is immersed in a solution which contains a higher concentration of solutes than that within its own cells or fluids hyperthermophiles -organisms that grow at very high temperatures

(between 80 °C and 100 °C) hyposmotic stress -an osmotic stress produced when a cell or organism is immersed in a solution which contains a lower concentration of solutes than that within its own cells or fluids ice-active protein-a protein that affects the formation and/or stability of ice ice-nucleating protein-a protein that acts as an ice nucleator ice nucleators -substances that cause ice nucleation (see nucleation)

impermeable-a membrane (or other structure) is impermeable to a substance if it does not allow that substance to pass through it inoculative freezing-the freezing of an organism as a result of ice from its surroundings travelling across its surface inorganic compounds -originally referred to chemical compounds that did not derive from living organisms but now generally refers to chemical compounds that do not contain carbon intracellular-inside the cells of an organism invertebrate - an animal without a backbone ion-an atom or molecule with a net electrical charge kinetic energy-a form of energy possessed by an object by virtue of its motion kingdom-the highest taxonomic classification below the domain (e.g. plants, animals)

late embryogenesis-abundant proteins -proteins that are produced by plant seeds during the later stages of their development latent heat of crystallisation (latent heat of fusion) -the heat released during the conversion of a substance from a liquid to a solid (as in the freezing of water) lichen-a symbiotic association between a fungus and an alga or cyanobacterium, which forms an encrusting or plant-like growth lipid -a group of organic compounds that are insoluble in water

(includes fats, phospholipids, oils and waxes) liverworts-small flowerless plants that lack roots and which reproduce by producing spores lower lethal temperature-the lowest temperature that an organism will survive membrane-a sheet-like layer that forms partitions within a cell, and between a cell and its surroundings, and which consists of a double layer of lipids with associated proteins and carbohydrates metabolism -the chemical processes that occur within an organism and which keep it alive methanogen-an organism that produces methane microorganism-refers to any organism that is too small to be seen with the naked eye; usually used in relation to bacteria, archaea, fungi, algae, viruses and protists mitochondrion (plural: mitochondria) -the organelle of eukaryotic cells in which the processes of respiration and energy production occur molecular chaperones-proteins that assist in the correct folding of other proteins molluscs-a phylum of invertebrate animals, including snails, slugs, octopus and squid Monera-a term sometimes used for all prokaryotic organisms moss -see bryophyte multicellular - consisting of many cells mutation-a change in the structure of a gene mutualism -a symbiotic relationship in which both partners in the association benefit nematodes-a phylum of worm-like invertebrate animals that are parasitic in animal or plants, or free-living in soil and in freshwater and marine sediments niche-see ecological niche nucleation (of ice formation)-the initial process which results in the formation of an ice crystal nucleic acids (see DNA and RNA)-organic molecules involved in the reproduction of organisms and which consist of subunits called nucleotides nucleotide-one of the basic structural units of nucleic acids (DNA and RNA)

nucleus -a membrane-bound organelle that contains the genetic material of a eukaryotic cell organelle-refers to a variety of organised and specialised structures

(often membrane bound) found in cells organic compounds -originally referred to chemical compounds that derived from living organisms but now generally refers to chemical compounds that contain carbon osmobiosis - surviving a cessation of metabolism due to osmotic stress osmolyte-an osmotically active substance osmosis -the process by which molecules of a solvent tend to pass through a semi-permeable membrane from a less concentrated solution into a more concentrated one osmotic stress -see hyperosmotic stress and hyposmotic stress osmotically inactive water-water that is not free to move under an osmotic stress (also sometimes called 'bound water' or 'unfreez-able water')

panspermia-the theory that life on Earth arose from microorganisms travelling through space parasitism -an association between two organisms in which one partner (the parasite) causes harm to the other (the host) pelagic-living in the open sea permafrost-permanently frozen ground permeable-a membrane (or other structure) is permeable to a substance if it allows that substance to pass through it pH-a measure of the acidity or alkalinity of a solution (the concentration of hydrogen ions on a logarithmic scale) phospholipid-a lipid containing a phosphate group as part of its molecule photoperiod-the relative length of night and day photosynthesis -the process by which plants, and some other organisms, use the energy from sunlight to produce sugars from carbon dioxide and water phototroph -an organism that is able to produce organic compounds from simple inorganic compounds by using the energy from sunlight phylum (plural: phyla) -a taxonomic category used in the classification of organisms (ranks above class and below kingdom) phytoplankton -microscopic plants and algae drifting in sea or freshwater piezophile-an organism that grows best at high pressures piezotolerant-an organism that tolerates high pressure but which grows best at lower pressures plasma membrane-the outer membrane which encloses a cell pogonophorans-a phylum of worm-like marine invertebrate animals polychaetes - a group of annelid worms polyol-a sugar alcohol (e.g. glycerol, sorbitol)

polysaccharides-large molecules consisting of repeating sugar sub-units prebiotic-before the emergence of life prefreeze mortality -see chilling intolerance primary producer-organisms that use the energy from sunlight or chemical processes to produce organic material from inorganic compounds productivity-the rate of production of new biomass by an organism, population or ecological community prokaryote-an organism whose cell lacks a membrane-bound nucleus and organelles proteins -large molecules consisting of chains of amino acids, which are essential components of the structure and function of all organisms protists -eukaryotic organisms that are not included among the animals, plants or fungi; most are unicellular protoplanetary disc-a flattened disc of dust around a star that may eventually coalesce to form planets protozoa-animal-like protists psychrophile-an organism that grows best at low temperatures psychrotolerant-tolerating low temperatures but growing best at higher temperatures quiescence-a period of dormancy radical-a molecule that contains at least one unpaired electron recrystallisation (of ice)-a change in the size and/or shape of ice crystals recrystallisation inhibitor-a substance that inhibits recrystallisation rehydrins -proteins in plants that are induced by rehydration relative humidity-a measure of the degree of dryness or wetness of air (the amount of water vapour present in air expressed as a percentage of the amount needed to saturate it with water at the same temperature)

remote-operated vehicle (ROV)-an unmanned submarine operated by cable from a ship on the surface of the sea renaturation -the restoration of the shape or conformation of a protein and the recovery of its biological function resistance adaptation-the survival of extreme environmental conditions by a period of dormancy resurrection plants - desiccation-tolerant higher plants RNA (ribonucleic acid)-a nucleic acid found in all cells whose main role is to carry the instructions from DNA for the synthesis of proteins rotifers (wheel animalcules)-a phylum of microscopic invertebrate animals; the name refers to a circle of cilia around the head, the beating of which gives the appearance of a rotating wheel salinity -the concentration of salts in a solution saltern-a pool where seawater is left to evaporate to make salt saturated fatty acids -fatty acids that do not contain double bonds semi-permeable membrane-a membrane with pores that allows the passage of small molecules (such as water) but not large molecules slime mould-a simple organism (protist) that consists of a creeping mass of jelly-like protoplasm or cells solute-a substance that is dissolved in a solution solution-a liquid mixture of two or more substances species richness-the number of species present in a given area spiracle-the respiratory opening of an insect or other arthropod spore-the resistant stage of a microorganism or plant springtails (collembolans)-a group of small wingless insects stomata-pores in the leaves and stems of plants that allow gas exchange supercooling-the maintenance of a fluid in a liquid state at temperatures below its melting point supercooling point-the temperature at which a supercooled fluid freezes symbiosis - a close association between two organisms tardigrades (water bears)-a phylum of microscopic invertebrate animals temperature of crystallisation-see supercooling point thermal hysteresis -a difference between the melting point and the freezing point of a solution, in the presence of an ice crystal thermal hysteresis proteins - see antifreeze proteins thermobiosis -surviving a cessation of metabolism due to high temperatures thermophile -an organism that grows best at high temperatures thermotolerant-tolerating high temperatures but growing best at lower temperatures thiobacilli-a group of bacteria that use sulphur as an energy source tidal heating -heating produced as a result of variation in the gravitational forces acting on a planet or moon torpor-a period of dormancy transpiration-the loss of water by a terrestrial plant, usually via the leaves tundra - treeless regions of the Arctic or mountains where the subsoil is permanently frozen ultraviolet (uv) radiation-that which has a wavelength shorter than that of the violet end of the visible spectrum but longer than that of X-rays unfreezable water -see osmotically inactive water unicellular-consisting of a single cell unsaturated fatty acids -fatty acids containing one or more double bonds vertebrate-an animal with a backbone vitrification - conversion into a glass or glass-like substance X-rays - electromagnetic radiation of high energy and very short wavelength (between that of ultraviolet and gamma rays) yeast - a unicellular fungus

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