Origins of life research uses scientific terms that may be unfamiliar to people outside of the field. We have compiled this glossary to help you find the meaning of any unfamiliar words. Because origins of life research is interdisciplinary, we consulted multiple life and physical science dictionaries and encyclopedias in developing our particular list. Please let us know your thoughts by sending an email to We welcome constructive suggestions for improvement.

Abiotic: Physical rather than biological; not derived from living organisms.  Nonliving environmental factors such as sunlight, temperature, winds, and precipitation that may affect living organisms.
Adenine: A nucleobase (a purine base) consisting of two carbon nitrogen rings (C5H5N5).  One of the four main nucleobases found in DNA and RNA, along with cytosine (C), guanine (G), and thymine (T) (uracil in RNA).  It is matched with thymine in DNA and uracil in RNA. 
Alcohol: A type of organic compound in which the hydroxyl functional group ( OH) is bound to a carbon atom.  Includes ethanol (C2H5OH) and methanol (CH3OH) – both of which have been found in interstellar space. 
Aldehyde: A type of organic compound characterized by the CHO group.  Includes formaldehyde (H2CO or equivalently HCHO) and glycoaldehyde (CH2OHCHO) – both of which have been found in interstellar space.  Aldehydes tend to be fragrant.
Aliphatic: A type of organic compound characterized by the CHO group.  Includes formaldehyde (H2CO or equivalently HCHO) and glycoaldehyde (CH2OHCHO) – both of which have been found in interstellar space.  Aldehydes tend to be fragrant.
Amino: (group) A functional group that consists of a nitrogen atom single bonded to two hydrogen atoms (NH2) or other groups.  It is associated with amines, amides, and amino acids.
Amino acid: An organic molecule possessing both carboxyl (COOH) and amino (NH2) groups.  Amino acids form peptide chains which serve as the monomers of proteins.  Although about 500 amino  acids are known, only 22 amino acids are involved in biological systems.
Amphiphile: A chemical compound possessing both hydrophilic (water dissolving) and lipophilic (lipid dissolving) properties.  Sometimes described as possessing both “water loving” and “fat loving” properties.
Archean: The Archean is a geologic eon preceding the Proterozoic Eon and lasting from about 3.8 to 2.5 billion years ago.  This eon was characterized by volcanism, continent building, a reducing atmosphere, and cyanobacteria.
Aromatic: Relating to organic compounds that contain at least one benzene ring (C6H6) or similar ring shaped component; e.g. naphthalene and phenanthrene.
Assimilation: The incorporation or conversion of nutrients into protoplasm that in animals follows digestion and absorption and in higher plants involves both photosynthesis and root absorption.
Asteroid: Most asteroids consist of rock, sometimes metal, in orbit around the Sun.  Most asteroids lie within the inner Solar System in an area referred to as the asteroid belt.  This belt lies between the planetary orbits of Mars and Jupiter.  Asteroids are believed to be ancient remnants from  the early formation of our solar system.
Astrobiology: The branch of biology concerned with the study of life on earth and in space.
Atmosphere: Mixture of gases that surround and are gravitationally attached to a planet.
Biomarker: A measurable substance in an organism whose presence is indicative of some  phenomenon such as disease, infection, or environmental exposure.
Biomass: Organic non fossil material of biological origin. For example, trees and plants are biomass.
Biopolymer: A type of large molecule which is abundant in nature.  Like polymers, biopolymers are chain like molecules made up of repeating chemical blocks and can be very long in length. The prefix bio means that they are produced by living organisms and thus are biodegradable. Biopolymers can be classified into three groups, depending on the nature of the repeating unit that they are made of: (i) polysaccharides made of sugars, (ii) proteins (polypeptides) made of amino acids, and (iii) nucleic acids (polynucleotides) made of nucleotides. The following substances are example biopolymers for each group: cellulose (found in plants), myoglobin muscle tissues), and DNA (genetic material of a given organism).
Bow shock: A sharp front formed in the solar wind ahead of the magnetosphere, marked with a sudden slowing down of the flow near Earth. It is quite similar to the shock forming ahead of the wing of a supersonic airplane. After passing near Earth, the slowed down flow gains speed again, to the same value as the surrounding solar wind.
Carbon star: A rare class of red giant stars unusually rich in carbon or carbon compounds.
Carbonyl: A carbonyl group is a functional group composed of a carbon atom double bonded to an oxygen atom (C=O).  It is found in aldehydes, ketones and many other chemical compounds.
Carboxylic: An organic acid characterized by the presence of at least one carboxyl group (the radical COOH).
Catalyst: Agent that starts or accelerates a chemical reaction, and itself emerges unchanged at the end of the reaction; this agent can be a molecule or larger assemblage, such as a clay surface area (as in the montmorillonite clay hypothesis); catalysts are most frequently proteins called enzymes, but they may be either inorganic or organic molecules.
Cation: A positively charged ion, formed when a metal loses electrons to a nonmetal and so becomes positively charged.
CFCs: Any of a class of compounds of carbon, hydrogen, chlorine, and fluorine, typically gases used in refrigerants and aerosol propellants. They are harmful to the ozone layer in the earth's atmosphere owing to the release of chlorine atoms upon exposure to ultraviolet radiation.
Chemical Process: Involving a reaction of some sort, a method or means of changing one or more chemicals or chemical compounds.  This can occur by itself or be caused by external forces.  To be contrasted with a physical process, where no chemical change occurs.
Chirality: A property of asymmetry.  An object or a system is chiral if it is not identical to its mirrorimage (see homochirality).
Comet: Body of ice, rock and organic compounds that orbits the Sun and expels a trail of gas and dust as the result of solar heating.  Light from the Sun causes the trail to glow, making the “tail” which can be visible in the night sky.  Comets are believed to be ancient remnants of the earliest years of the formation of our solar system, originating in a region beyond the orbits of the outermost major planets.
Covalent: The physical upwelling of hot matter, thus transporting energy from a lower, hotter region to a higher, cooler region. A bubble of gas that is hotter than its surroundings expands and rises. When it has cooled by passing on its extra heat to its surroundings, the bubble sinks again. Convection can occur when there is a substantial decrease in temperature with height.
Coronal Mass Ejections: Huge bursts of solar wind rising above the Sun's corona. One of the biggest explosions in our solar system.
Cosmic rays: Extremely high energy subatomic particles that continuously bombard Earth and other planetary bodies from all directions.
Cytosine: One of the four main nucleobases found in DNA and RNA, along with adenine (A), guanine (G), and thymine (T) (uracil in RNA).  Its chemical formula is C4H5N3O.
Dark matter:   Nonluminous matter not yet directly detected by astronomers that is hypothesized to exist to account for various observed gravitational effects.
DNA  A type of nucleic acid consisting of two twisted strands of nucleotide monomers with deoxyribose sugars that are connected by the nitrogenous bases adenine (A), cytosine (C), guanine (G), and thymine (T).  DNA contains the genetic material that informs all living cells and many viruses.  It can replicate itself and also serves as a template for the synthesis of RNA.
Doppler Shift: The Doppler shift is a shift in the wavelength of light or sound that depends on the relative motion of the source and the observer. 
Early Earth: A term usually defined as Earth's first billion years (4.6 to 3.6 billion years ago).
Earth: Like, resembling or characteristic of earth; "earthlike atmosphere".
Enantiomer: One of two stereoisomers that are mirror images of each other but cannot be superposed, much as one’s left and right hands are the same except for their opposite orientations.
Enantiomeric Excess: A measure of the extent to which a particular enantiomer dominates in a mixture.  Many organic compounds have "R" and "S" enantiomers that may coexist in the same  solution but not always in equal amounts.
Enzyme: A type of large molecule that selectively catalyzes (i.e. increases the rates of) chemical reactions between specific molecules. Includes proteins and some RNA molecules.
Eukaryote: An organism whose cells each contain a nucleus and other organelles enclosed within membranes.  The cell’s DNA resides within the nucleus, bound together by proteins (histones) into chromosomes.
Exoplanet: A planet that does not orbit the Sun and instead orbits a different star, stellar remnant, or brown dwarf.
Fatty Acid: A long carbon chain of carboxylic acid which is either saturated or unsaturated.  The general chemical formula is CnH2n+1COOH.  Fatty acids vary in length and in the number and location of double bonds; three fatty acids linked to a glycerol molecule form fat.
Fissure: A crack extending far into a planet or moon through which magma travels to and erupts onto the surface.
Fractionation: A separation process in which a certain quantity of a mixture (gas, solid, liquid, suspension or isotope) is divided during a phase transition, into a number of smaller quantities (fractions) in which the composition varies according to a gradient.
Genetics: The biological field of inquiry that deals with the transfer of biological information from one  generation to the next via the mechanisms of information rich polymers, such as DNA and RNA.  Genetic processes govern heredity and the variation of inherited traits among related organisms. 
Geochemical: The chemistry of the composition and alterations of the matter comprising the Earth or other (typically rocky) celestial body.  Includes the chemical properties and changes in the body’s minerals, rocks, soil, waters, and atmosphere.
Geochemical Cycle: the developmental path followed by individual elements or groups of elements in the crustal, sub-crustal, and surface zones of a planet. This can include natural separation  and/or concentration of elements, along with heat assisted or elemental recombination processes.
Geophysical: The physics of the Earth and its environment, encompassing the fields of seismology, oceanography, and meteorology.
Geospace: The area of space surrounding the Earth but outside of the Earth's atmosphere  influenced  by the particles and fields coming from the Sun.
Glycerol: Simple polyol (sugar alcohol) compound that is soluble in water, sweet and syrupy (C3H8O3). Also known as glycerine.
Guanine: One of the four main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, (A) cytosine (C), and thymine (T) (uracil in RNA).  Its chemical formula is (C5H5ON5).
Hadean: The first geologic eon of Earth preceding the Archean. It began with the formation of the Earth about 4.54 billion years ago and extends to about 3.8 billion years ago. The name "Hadean"comes from Hades, the ancient Greek god of the underworld, in reference to the "hellish" conditions on Earth at the time: the planet had just formed and was still very hot due to high volcanism, a partially molten surface and frequent collisions with other Solar System bodies. No surface rocks are known to have survived from this eon, though some may be preserved on the Moon!  Note: A Period is the basic unit of geological time in which a single type of rock system is formed. Two or more periods comprise a geological Era. Two or more Eras form an Eon, the largest division of geologic time.  
Homochirality: A property of some materials where all the constituent units are molecules of the same chiral form (enantiomer). In biology, homochirality is a common property of amino acids and sugars.
Hydrology: The science that deals with global water (both liquid and solid), its properties, circulation, and distribution, on and under the Earth's surface and in the atmosphere through            evapotranspiration or is discharged into oceans.
Hydrophilic: A property of a molecule where it is typically charge polarized (polar) and capable of hydrogen bonding, thus enabling it to dissolve more readily in water than in oil or other similar solvents.
Hydroxyl: A chemical functional group containing an oxygen atom connected by a covalent bond to a hydrogen atom, a pairing that can be simply understood as a substructure of the water molecule (OH).
Ice Cores: An ice core is a core sample that is typically removed from an ice sheet, most commonly from  the polar ice caps of Antarctica, Greenland or from high mountain glaciers elsewhere.
Interstellar: Between the stars.
Ionosphere: The part of the earth's atmosphere in which ionization of atmospheric gases affects the  propagation of radio waves, which extends from about 30 miles (50 kilometers) to the exosphere, and which is contiguous with the upper portion of the mesosphere and the thermosphere.
Isotope: An atom having the same atomic number (number of protons in the nucleus) as another atom but differing in atomic weight (due to different numbers of neutrons in the nucleus).
Isomeric: Isomers are molecules with the same molecular formula but different chemical structures.
Late Heavy       Bombardment: A hypothesized period between 4.1 and 3.8 billion years ago that was characterized by excess numbers of asteroids and other debris in the inner Solar System.  The resulting bombardments are thought to have re melted the Earth’s surface and produced the cratering that is still evident on the Moon, Mercury, and Mars.
Light Curve: A graph showing the variation in the light received over a period of time from a variable star or other varying celestial object.
Lipid: One of a family of compounds, including fats, phospholipids, and steroids that are insoluble in water.
Lipophilic: A chemical compound’s ability to dissolve in fats, oils, lipids, and non-polar solvents.
Magnetic Storms: A large scale disturbance of the magnetosphere, often initiated by the arrival of an interplanetary shock originating at the Sun. 
Magnetosphere: The region surrounding a celestial body where its magnetic field controls the motions  of charged particles.
Meteor: Any of the small particles of matter in the solar system that are directly observable only by their incandescence from frictional heating on entry into the atmosphere.
Meterology: The branch of science concerned with the processes and phenomena of the atmosphere, especially as a means of forecasting the weather.
Meteorite: A solid piece of matter, usually stone or metal, that originated beyond Earth and has survived impact with the Earth’s surface.  Most are fragments of asteroids and comets, but some are blast ejecta from the Moon, Mars, and other planets.
Molecular Fossil: The preservation of organic material from dead organisms. This type of fossil is very delicate, because it is based on the very molecular structures that made up the organism. It is therefore very susceptible to decay, as chemical reactions break apart the bonds that hold the molecule together. However, traces of organic molecules are still found, and with the advance of technology, much more will be uncovered in the years ahead. Until relatively recently, technology has not been capable of analyzing the molecular structures of fossils. The field of molecular fossil study has only been accessible to scientists within the last few years. Thus, today, very little is known about the molecular fossil record.
Monomer: A molecule that may bind chemically to other molecules to form a polymer.  For example, glucose molecules (C6H12O6) are monomers that can combine to form the polymer cellulose (C6H10O5)n
Montmorillonite: A type of clay consisting of an aluminum silicate in which calcium is readily exchangeable with other cations.  Montmorillonite is also known to cause micelles (lipid spheres) to assemble together into vesicles. These are structures that resemble cell membranes on many cells. It can also help nucleotides to assemble into RNA which will end up inside the vesicles. This catalytic process involving monmorillonite clays could have generated highly complex RNA polymers that could reproduce the RNA trapped within the vesicles. This process may have led to the origin of life on Earth (the Montmorillonite clay hypothesis).
Noachian Mars: The Noachian is a geologic system and early time period on the planet Mars characterized by high rates of meteorite and asteroid impacts and the possible presence of abundant surface water. The absolute age of the Noachian period is uncertain but probably corresponds to the lunar Pre Nectarian to Early Imbrian periods of 4.1 to 3.7 billion years ago, during the interval known as the Late Heavy Bombardment. Many of the large impact basins on the Moon and Mars formed at this time. The Noachian Period is roughly equivalent to the Earth’s Hadean and early Archean eons when the first life forms likely arose.
Nova: A star showing a sudden large increase in brightness and then slowly returning to its original state over a few months.
Nucleotide: A type of biological molecule that forms the building blocks of nucleic acids (DNA and RNA) and serves to carry packets of energy (ATP) within the cell.  Consists of a nitrogenous base, a five carbon sugar (ribose or deoxyribose), and one or more phosphate groups.
Oligonucleotide: Short polymer of two to twenty nucleotides.
Orbital Period:  The time it takes to complete one full orbit around a celestial body.
Organelle: A specialized subunit within a cell that has a specific function; it is usually separately enclosed within its own lipid bilayer.
Organic Compound:  Any member of a class of liquid, gaseous or solid chemical compound, whose molecules contain carbon.
Origins of Life: Multi-disciplinary research aimed at revealing the emergence of life from the chemistry associated with the early Earth and other planetary environments.
Ozone: A colorless unstable toxic gas with a pungent odor and powerful oxidizing properties, formed from oxygen by electrical discharges or ultraviolet light. It differs from normal oxygen (O2) in having three atoms in its molecule (O3).
Peptide: A short chain of amino acid monomers linked by a peptide (amide) bond (CONH2).  Peptides are always smaller than proteins (which are made of polypeptides).
Phospholipid: A class of phosphorus containing lipids, such as lecithin and cephalin, that are composed mainly of fatty acids, a phosphate group, and simple organic molecules such as glycerol.  They have hydrophilic heads (made of a negatively charged phosphate group and a  glycerol  molecule) and hydrophobic tails (made of fatty acids).  Phospholipids are a major component of all cell membranes as they can form lipid bilayers.
Photochemistry: A sub discipline of chemistry involving chemical reactions that proceed from the absorption of light by atoms or molecules.  Everyday examples of photochemical processes include photosynthesis, the degradation of plastics, and the formation of vitamin D with sunlight.
Phylogeny: The history of the evolution of a species or group, with emphasis on the lines of descent and the relationships among broad groups of organisms.
Planetary   Environment: Fundamental processes governing the atmosphere of a planet.
Planetary Habitability:   The measure of a planet's or a natural satellite's potential to develop and sustain life.
Polycyclic Aromatic Hydrocarbon (PAH): A type of complex organic molecule that is made from benzene rings (C6H6) arranged in sheets (e.g. anthracene and fluorine).  PAHs are found on Earth, in oil and coal deposits and as byproducts of fuel burning.  In space they are found in star forming nebulae. 
Polymer: Any of numerous natural and synthetic compounds of usually high molecular weight consisting  of up to millions of repeated linked monomers, each being a relatively lighter and simpler molecule.
Polymerization: The process through which simple molecules join via chemical reactions to form complex molecules that contain repeating structural units of the original molecules, preserving their functional integrity; formation of a polymer by a succession of similar linkages between monomers; polymerization may occur either through addition in which the whole monomer is   incorporated into the polymer, or by condensation, in which the linkage is formed through  elimination of a small molecule (e.g. H2O in the case of the peptide linkage).
Prebiotic: Chemical and physical processes occurring or existing before the emergence of life.
Prebiotic Chemistry: The study of the abiotic synthesis of organic compounds which may have been necessary for the origin of life.
Prebiotic Synthesis: The plausible pathways by which the molecular precursors of life may have formed  on the primitive Earth.
Prokaryote: A type of microbial organism, whose cells lack a membrane bound nucleus.  Therefore, the  cell’s DNA is not confined to a closed nuclear entity, and there is no endoplasmic reticulum. Includes archaea and bacteria.
Protein: Large biological molecule, or macromolecule, consisting of one or more chains of amino acids connected by peptide bonds (CONH2) in varied three dimensional structures.  Proteins perform a wide variety of biological functions within the cell.
Protocell: A macromolecular structure that is theoretically made up of two molecular components: a  RNA replicase and a fatty acid membrane. An extremely pared down and simple version of a  cell, the protocell is nonetheless capable of growing, replicating and evolving.  This self organized, endogenously ordered, spherical collection of polypeptides is proposed as a stepping stone to the origin of life.
Purine: Any of a group of organic compounds containing two fused rings of carbon and nitrogen atoms.  Includes the two nitrogenous bases adenine and guanine in DNA and RNA.
Quantum Theory of Matter: A theory in physics based on the principle that matter and energy have the  properties of both particles and waves, created to explain the radiation of energy from a blackbody, the photoelectric effect, and the Bohr theory, and now used to account for a wide range of physical phenomena, including the existence of discrete packets of energy and matter,  the uncertainty principle, and the exclusion principle.
Radial Velocity The velocity of a star or other body along the line of sight of an observer.
Radical: A group of atoms that behaves as a unit in chemical reactions and is often unstable except as part of a molecule.  The hydroxyl, ethyl, and phenyl radicals are examples.
Radiometer: An instrument for detecting or measuring the intensity or force of radiation.
Reactant:  A substance that is consumed in the course of a chemical reaction.
Red Giant: A very large star of high luminosity and low surface temperature. Red giants are thought to  be in a late stage of evolution when no hydrogen remains in the core to fuel nuclear fusion.
Regolith: The layer of unconsolidated rocky material covering bedrock.
Ribonucleotide: A nucleotide that contains ribose as its sugar and is a component of RNA.  Once reduced, it becomes a deoxyribonucleotide, the building block of DNA.
Ribose: The five carbon sugar that serves as a component of RNA (C5H10O5).  Phosphorylated derivatives of ribose such as ATP and NADH play central roles in metabolism.
Ribozyme: A non-protein enzyme composed of an RNA segment that catalyzes the template directed  assembly of complex RNA molecules from simpler molecules (the process called polymerization)
RNA (Ribonucleic Acid): A type of nucleic acid consisting of a single strand of nucleotide monomers with a ribose sugar backbone, to which the nitrogenous bases adenine (A), cytosine (C), guanine (G), and uracil (U) are attached.  RNA catalyzes protein synthesis and carries genetic information.
Seismic Tomography: A technique for imaging Earth's subsurface characteristics in an effort to understand deep geologic structure.
Snow Line: The altitude above which some snow remains on the ground in a particular place throughout the year.
Solar System: Refers to a star and all of the objects that travel in orbit around it.  Our solar system consists of the Sun (our star), eight planets and their natural satellites (such as our moon); dwarf  planets; asteroids and comets. Our solar system is located about 28,000 light years from the center of our Milky Way galaxy near or within one of the Galaxy’s spiral arms.
Solar Type Star: Stars that are particularly similar to the Sun.
Spatial Analysis: A type of geographical analysis which seeks to explain patterns of human behavior and its spatial expression in terms of mathematics and geometry, that is, locational analysis.
Spectrometer: An apparatus used for recording and measuring spectra, especially as a method of analysis.
Spectroscopy: The branch of science concerned with the investigation and measurement of spectra produced when matter interacts with or emits electromagnetic radiation.
Spectrum: A band of colors, as seen in a rainbow, produced by separation of the components of light by their different degrees of refraction according to wavelength.
Spin Polarized Secondary Electrons: A narrow electron beam strikes a magnetic surface at a microscopic level.  This results in spin polarization of the emitted secondary electrons generating usable data.
Stellar UV Flux: The flow of ultraviolet light in space from the gaseous “surfaces” of stars.  The hotter the star’s surface, the greater the UV flux is.
Stereoisomers: Isomeric molecules that have the same molecular formula and sequence of bonded atoms (constitution), but that differ only in the three dimensional orientations of their atoms in     space.  There are two types of stereoisomers – geometric isomers and enantiomers.
Steroid: A type of organic compound that is based on 17 carbon atoms arranged in four fused cycloalkane rings.  Steroids include many biologically important compounds, including           cholesterol and other sterols, animal hormones, plant alkaloids, and certain forms of vitamins. 
Stratospheric: The part of the earth's atmosphere which extends from the top of the troposphere to about 30 miles (50 kilometers) above the surface and in which temperature increases gradually   to about 32° F (0° C) and clouds rarely form.
Supernova: The death explosion of a massive star whose core has completely burned out. Supernova explosions can temporarily outshine a galaxy. The outer layers are blasted out in an expanding cloud. This cloud is visible long after the initial explosion fades, and is called a supernova remnant (SNR).
Synthesis: The formation of a more complex substance from simpler ones.
Tectonics: General term referring to the large scale change of rock in response to forces causing faulting and folding. The forces acting upon a rock mass are generally termed compressional      (squeezing together), tensional (pulling apart), or shear (parallel sliding). Common land forms resulting from tectonic processes are mountain ranges, rift zones, faults, fractured rock, and folded rock masses.
Thymine: One of the four nucleobases in the nucleic acid of DNA that is represented by the letter (T). The other nucleobases are adenine (A), cytosine (C), and guanine (G).  Its chemical formula is C5H6N2O2.  Thymine is structurally analogous to uracil (U) in RNA.
Transit Tropospheric: The lowest densest part of the earth's atmosphere in which most weather changes occur and temperature generally decreases rapidly with altitude and which extends from the earth's surface to the bottom of the stratosphere.
Ultraviolet: Electromagnetic radiation resembling visible light, but of shorter wavelength. The eye cannot see UV, and much of it is absorbed by ozone, a variant of oxygen, at altitudes of 30-40 km
Uracil: One of the four nucleobases in the nucleic acid of RNA that is represented by the letter (U).  The other nucleobases are adenine (A), cytosine (C), and guanine (G).  Its chemical formula is   C4H4N2O2.  Uracil is structurally analogous to thymine (T) in DNA.
Volatile: In planetary science, a volatile is a chemical element or chemical compound with a low boiling temperature. Volatiles are associated with a planet’s or moon's crust and/or atmosphere. Examples include hydrogen, nitrogen, water, carbon dioxide, ammonia, methane, and sulfur dioxide.  Volatiles are the first to escape a planetary body’s gravity when energized by an   external source (e.g. the body’s host star).