 |
 Science Glossary |
Click on 1st letter of the term you wish to find : |
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A nitrogenous base, one member of the base pair AT (adenine-thymine). See also: base pair, nucleotide www.ornl.gov/TechResources/Human_Genome/glossary/glossary.html |
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algae |
Simple rootless plants that grow in sunlit waters in relative proportion to the amounts of nutrients available. They are food for fish and small aquatic animals, and a factor in eutrophication (Source: Mintzer, 1992). |
alleles |
variant forms of the same gene. Different alleles produce variations in inherited characteristics such as eye color or blood type. www.accessexcellence.org/AE/AEPC/NIH/gene27.html -- Genes which are interchangeable on a DNA strand. Example = Blue and Brown eyes are single gene alleles. al.lele n [Allel, short for Allelomorph] (1928) 1: any of the alternative forms of a gene that may occur at a given locus 2: either of a pair of alternative Mendelian characters (as smooth and wrinkled seed in the pea) home.attbi.com/~bkrentzman/glossary.html
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| asteroid | Any of the thousands of small rocky objects that orbit around the Sun, most of them between the orbits of Mars and Jupiter (although some pass closer to the Sun that Earth does and others have orbits that take them well beyond Jupiter). The largest asteroid is one called Ceres; it's about as wide as the state of Texas. Any one of the thousands of bodies in space ranging in size from large boulders to miles in diameter which orbit the sun in a region known as the asteroid belt. The asteroid belt lies between the orbits of mars and Jupiter. To date, over two thousand of these bodies have been identified and catalogued. The largest asteroids are Chiron, Astraea, Juno, Vesta, Pallas and Ceres. |
atom |
An atom is the smallest unit of an element that still has all the properties of that substance. In most cases, an atom consists of protons, neutrons, and electrons. The protons and neutrons are found in the center of the atom, called the atomic nucleus, and the electrons orbit or circle around the center of the nucleus in paths called orbitals. ( www.studyisland.com) The smallest particle into which a chemical element can be divided and still retain the properties characteristic of the element; consists of a central core or nucleus composed of PROTONs and NEUTRONs, encircled by one or more ELECTRONs that move around the nucleus in characteristic orbits whose distance from the nucleus depends on their energy. (Greek, atomos, indivisible). |
Atomic mass |
The mass of a neutral atom. Its value in atomic mass units (u) is approximately equal to the sum of the number of protons and neutrons in the nucleus of the atom. the mass of an atom expressed in atomic mass units (amu); the total number of protons and neutrons in the nucleus. |
atomic number |
The atomic number of an atom is equal to the number of protons that the atom contains. Atoms can have differing numbers of neutrons and electrons while still retaining the original characteristic properties of that atom. However, if an atom gains or loses a proton, in essence, it changes its atomic number and becomes an entirely new atom with new characteristics. ( www.studyisland.com) The number of protons in an atomic nucleus. For an neutral atom, this also corresponds to the number of electrons orbiting the nucleus. This number also denotes an atom's place on the Periodic Table of the Elements and the Chart of Nuclides. Carbon has an atomic number of 6: 6 protons and 6 electrons. |
atomic weight |
The atomic weight of an atom is a measure of how much mass an atom has. The atomic weight is calculated by adding the number of protons and neutrons together. Atomic masses are not listed as whole numbers on the periodic table because atoms can come in forms with different amounts of neutrons. The atomic weight reported for any particular element is an average weight of all the known forms of that element. ( www.studyisland.com) The atomic weight of an atom is a measure of how much mass an atom has. The atomic weight is calculated by adding the number of protons and neutrons together. Atomic masses are not listed as whole numbers on the periodic table because atoms can come in forms with different amounts of neutrons. The atomic weight reported for any particular element is an average weight of all the known forms of that element. |
autoimmune disease |
A disease in which the body produces an immunogenic (i.e., immune system) response to some constituent of its own tissue. In other words the immune system loses its ability to recognize some tissue or system within the body as "self" and targets and attacks it as if it were foreign. Autoimmune diseases can be classified into those in which predominantly one organ is affected (e.g., hemolytic anemia and anti-immune thyroiditis), and those in which the autoimmune disease process is diffused through many tissues (e.g., systemic lupus erythematosus). For example, multiple sclerosis is thought to be caused by T cells attacking the sheaths that surround the nerve fibers of the brain and spinal cord. This results in loss of coordination, weakness, and blurred vision. |
Single-celled organisms, free-living or parasitic, that break down the wastes and bodies of dead organisms, making their components available for reuse by other organisms. Bacteria are single-celled organisms that live in and around us. Bacteria may be helpful, but in certain conditions may cause illnesses such as strep throat, most inner ear infections, and bacterial pneumonia. Pl. a unicellular prokaryotic organism that usually multiplies by cell division and has a cell wall that provides a constancy of form. They may also be aerobic or anaerobic, motile or non-motile and free-living, saprophytic, parasitic or pathogenic. |
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blastula |
early stage of an embryo produced by cleavage of an ovum; a liquid-filled sphere whose wall is composed of a single layer of cells; during this stage (about eight days after fertilization) implantation in the wall of the uterus occurs |
-- any malignant growth or tumor caused by abnormal and uncontrolled cell division; it may spread to other parts of the body through the lymphatic system or the blood stream www.cogsci.princeton.edu/cgi-bin/webwn -- A general term for more than 100 diseases characterized by abnormal and uncontrolled growth of cells. The resulting mass, or tumor, can invade and destroy surrounding normal tissues. Cancer cells from the tumor can spread through the bloodstream or lymph system to start new cancers in other parts of the body. |
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cellular respiration |
The process whereby carbon-containing compounds are broken down through a series of reactions that result in the gradual release of energy stored as ATP. Usually, this process uses oxygen and releases carbon dioxide and water as by-products. The process in which a cell breaks down sugar or other organic compounds to release energy used for cellular work; may be anaerobic or aerobic, depending on the availability of oxygen. |
centromere |
In mammalian genetics, the primary constriction of a chromosome separating it into the short arm (p) and the long arm (q). The centromere is the chromosomal region over which the kinetochore is organized. See the Figure at NHGRI.Mouse chromosomes have centromeres close to one end and have essentially no short arm. See the idiogram of the mouse karyotype at the Department of Pathology at the University of Washington. www.informatics.jax.org/mgihome/other/glossary.shtml the center part of a chromosome that appears ‘pinched’, in-between the p and q arms. |
chemosynthesis |
the formation of organic compounds with energy derived from inorganic substances such as ammonia, sulfur and hydrogen |
Chloroplast |
uses solar energy to form ATP ( www.studyisland.com) Chloroplasts are specialized organelles found in all higher plant cells. These organelles contain the plant cell's chlorophyll, hence provide the green color. They have a double outer membrane. Within the stroma are other membrane structures - the thylakoids and grana (singular = granum) where photosynthesis takes place. www.cellsalive.com/cells/chloropl.htm
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chromatids |
Each of the two daughter strands of a duplicated chromosome joined at the centromere during mitosis and meiosis. www.biotechwithitaly.com/nw_glossary_cd.html -- One of the pair of stands, formed by longitudinal splitting of a chromosome that are joined by a single centromere in somatic cells during mitosis; one of tetrad of strands formed by lengthwise splitting of paired chromosomes during the diplotene stage of meiosis. |
chromosome |
a structure of compact intertwined molecules of DNA found in the nucleus of cells. Chromosome contain the cell's genetic information. Humans normally have 46 chromosomes. aids.hallym.ac.kr/dict/c.html -- found in the nucleus of the cell and made of the [2: nucleic ] acid [1: DNA ] and [2: protein .] called chromatin. It contains the [2: genetic ] code that is transmitted when the sperm and egg combine to form a new organism. Small units on the chromosomes, called [2: genes ], determine the hereditary characteristics, such as eye colour, leaf shape etc. of the organism. [2: Genetics chapter on chromosomes ]; [3: chromosome number of various species ]; [3: what are telomeres? ]; [3: see human chromosmes (left) and chimpanzee chromosomes (right) ( ref )] [3: chromosomes of human, chimpanzee, gorilla, and orangutan ] |
| chromosphere | The thin (10 000 km) layer of relatively transparent gases, predominantly hydrogen and helium, above the photosphere and below the corona of the sun. It is best observed during total solar eclipse when its emission spectrum may be studied. The chromosphere (literally, "color sphere") is a thin layer of the Sun's atmosphere just above the photosphere, roughly 10,000 kilometers deep. The chromosphere is more visually transparent than the photosphere. |
codominant |
One of a series of terms applied to the phenotypic effect of a particular allele in reference to another allele (usually the standard wild-type allele) with respect to a given trait. An allele "a" is said to be codominant with respect to the wild-type allele "A" if the A/a heterozygote fully expresses both of the phenotypes associated with the a/a and A/A homozygotes. An example of codominance is the ABO blood type antigens in humans, where AA individuals are type A, BB individuals are type B, and AB individuals are type AB. See also Dominant, Recessive, Semidominant. |
codon |
a triplet of three letters (base pairs) of the DNA alphabet. www.chkd.com/Genetics/glossary.asp A section of DNA (three nucleotide pairs in length) or RNA (three nucleotides in length) that codes for a single amino acid. A sequence of three RNA or DNA nucleotides that specifies (codes for) either an amino acid or the termination of translation. |
| comet | (astronomy) a relatively small extraterrestrial body consisting of a frozen mass that travels around the sun in a highly elliptical orbit A comet is a small astronomical object similar to an asteroid but composed largely of ice. Comets typically move in highly elliptical orbits, the aphelia of which may be many times more distant than Pluto's orbit. Often described as "dirty snowballs", comets are composed largely of frozen carbon dioxide, methane and water with dust and various mineral aggregates mixed in. |
compound |
The chemical combination of two or more elements in fixed amounts is called a compound. |
| constellation | A constellation is a group of stars visibly related to each other in a particular configuration. In three-dimensional space, most of the stars we see have little relation to one another, but can appear to be grouped on the celestial sphere of the night sky. Humans excel at finding patterns and throughout history have grouped stars that appear close to one another into constellations. ... en.wikipedia.org/wiki/Constellation |
| convection zone | Region of a star's interior, lying just below the surface, where the material of the star is in constant convective motion. This region extends into the solar interior to a depth of about 20,000km. The convection zone is the outermost layer of the sun's interior. Energy is transferred there in convection currents. (A good example of convection current is a lava lamp.) |
| corona | The outermost layer of the solar atmosphere, characterized by low densities (<1.0E+09/cc) and high temperatures (>1,0E+06deg.K). a white or colored circle or set of concentric circles of light of small radius seen around a luminous body, esp. around the sun or moon. The color varies from blue inside to red outside and the phenomenon is attributed to diffraction of light by thin clouds or mist (distinguished from halo). |
| Cytokinesis | Cytokinesis refers to the division of a eukaryotic cell. Cytokinesis usually occurs after a cell has undergone nuclear division as part of mitosis or meiosis. Except for some special cases, the amount of cytoplasm in each daughter cell is the same. In animal cells, the cell membrane forms a cleavage furrow and pinches apart like a balloon. The cleavage furrow is formed by action of microfilaments. ... en.wikipedia.org/wiki/Cytokinesis |
Cytosine |
A nitrogenous base, one member of the base pair GC (guanine and cytosine) in DNA. See also: base pair, nucleotide doegenomestolife.org/glossary/glossary_c.html |
Diabetes is a disorder in which the body cannot convert foods properly into the energy needed for daily activities. Diabetes tends to get passed on genetically but factors other than heredity are responsible as well. There are two main types of diabetes. Type I, or insulin-dependent, is the more severe for of the disease. Type II, or adult onset, is the more common form and accounts for more than 85% of all cases. Diabetes cannot be cured, but it can be controlled. Control requires carefully regulating one's diet, regular exercise, and, if necessary, insulin. |
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Diffraction (waves) |
This occurs when a wave passes through a gap between two barriers and spreads out into a circular pattern. The amount of diffraction depends on the wavelength and the size of the gap. Diffraction is the apparent bending and spreading of waves when they meet an obstruction. It can occur with any type of wave, including sound waves, water waves, and electromagnetic waves such as light and radio waves. Diffraction also occurs when any group of waves of a finite size is propagating; for example, a narrow beam of light waves from a laser must, because of diffraction of the beam, eventually diverge into a wider beam at a sufficient distance from the laser. It is the diffraction of "particles," such as electrons, which stood as one of the powerful arguments in favor of quantum mechanics. |
diplotene |
the fourth stage of the prophase of meiosis |
DNA |
-- deoxyribonucleic acid. DNA molecules carry the genetic information necessary for the organization and functioning of most living cells and control the inheritance of characteristics. www.nti.org/e_research/e6_glossary.html The material inside the nucleus of cells that carries genetic information. The scientific name for DNA is deoxyribonucleic acid. www.ornl.gov/TechResources/Human_Genome/publicat/genechoice/glossary.html |
DNA helicase |
An enzyme that unwinds the double helix of DNA to allow for replication. |
DNA Nitrogen Bases |
DNA has four types of nitrogen bases: adenine, thymine, cytosine, and guanine. Adenine and Guanine are purines, or nitrogen bases made of two rings of carbon and nitrogen atoms. Thymine and cytosine are pyrimidines, or nitrogen bases made of a single ring of carbon and nitrogen atoms. The nitrogen bases are the only molecules to vary within a DNA molecule. |
Dominant gene |
-- A gene that is fully expressed in the phenotype of the heterozygote. www.pestmanagement.co.uk/library/gloss_d2.html -- A member of a gene pair which, if present, determines that the individual will show the trait controlled by the gene, regardless of whether the other member of the pair is the same or different (that is, recessive). See also recessive gene. |
the outer of the three cell layers which form, as the clump of early embryonic cells begins to differentiate. The ectoderm will form the epidermis of the skin and the nervous system. The other two layers are the mesoderm and the endoderm. The germ layer in an embryo that gives rise to the epidermis and nervous system. In many cases, as in vertebrates, an anterior and posterior invagination of ectoderm gives rise to the stomodeum and proctodeum, respectively. |
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Electrical charge of an atom |
The electrical charge of an atom is the sum of the number of protons (+1), neutrons (0), and electrons (-1). |
| electromagnetic energy | Energy rays that are either reflected or emitted as radiation by objects. X-rays, ultraviolet light, visible light, near-infrared light, and heat (thermal) radiation are different wavelengths of electromagnetic energy. Electrical energy or electromagnetic energy is a form of energy present in any electric field or magnetic field, or in any volume containing electromagnetic radiation. The SI unit of electrical energy is the joule, while the unit used by electrical utility companies is the watt-hour (W·h) or the kilowatt-hour (kW·h.) |
electron |
An electron is a negatively charged particle found circling or orbiting an atomic nucleus. An electron, like a proton, is a charged particle, although opposite in sign, but unlike a proton, an electron has negligible atomic mass. Electrons contribute no atomic mass units to the total atomic weight of an atom. ( www.studyisland.com) The least massive electrically charged particle, therefore absolutely stable. It is the most common lepton with charge -1. An electron is one of the fundamental particles in nature. Fundamental means that, as far as we know, an electron cannot be broken down into smaller particles. Electrons are responsible for many of the phenomena that we observe in everyday life. Mutual repulsion between electrons in the atoms of the floor and those within your shoes keeps you from sinking and disappearing into the floor!!! Electrons carry electrical current and successful manipulation of electrons allows electronic devices, such as the one you are using, to function. |
Electron affinity |
The electron affinity is a measure of the attraction between the incoming electron and the nucleus. The higher the attraction, the higher the electron affinity. |
Electron Cloud Model |
Erwin Schrödinger built upon the thoughts of Bohr yet took them in a new direction. He developed the probability function for the Hydrogen atom (and a few others). The probability function basically describes a cloud-like region where the electron is likely to be found. It can not say with any certainty, where the electron actually is at any point in time, yet can describe where it ought to be. Clarity through fuzziness, is one way to describe the idea. The model based on this probability equation can best be described as the cloud model.
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Electron energy level |
The concept of "special orbits" was extremely useful, it's just the orbits themselves that scientists don’t use anymore. Instead, we're going to think about electrons being in special energy levels. We just use this rule: Bigger Orbit = Higher Energy www.colorado.edu/physics/2000/quantumzone/bohr2.html In the electron cloud model of an atom, electrons found within electron shells travel around the nucleus in unpredictable patterns. Although every atom basically has an infinite number of shells for the electrons to move around in, the electrons tend stay in the electron shell that has the lowest energy and is closer to the nucleus. Electron shells are named K, L, M, N, O, P (from the shell closest to the nucleus moving outward). To fill the electron shells: K needs 2 electrons, L needs 8 electrons, M needs 18 electrons, N needs 32 electrons, O needs 18 electrons, and P needs 4 electrons. The last electron shell of an atom usually will contain no more than eight electrons. ( www.studyisland.com) |
element |
A substance composed of atoms having an identical number of protons in each nucleus. Elements cannot be reduced to simpler substances by normal chemical means. ( www.studyisland.com) Substance entirely composed of atoms of the same atomic number that cannot be further broken down into a chemical reaction. Currently there are 112 known elements, of which 92 occur naturally and 20 are artificial. Each element has a specific number of protons in its nucleus, referred to as the atomic number Z. Here are a few examples: hydrogen (Z = 1), carbon (Z = 6), gold (Z = 79), lead (Z = 82) and uranium (Z = 92). |
embryonic period |
During the embryonic period of pregnancy, which occurs from the third to the eighth week of pregnancy, three distinct germ layers, the ectoderm, mesoderm, and endoderm, form. All of the major organ systems will develop from these three germ layers.( www.studyisland.com) |
endoderm |
the inner of the three cell layers which form, as the clump of early embryonic cells begins to differentiate. The endoderm will form the gut system and its associated organs. The other two layers are the mesoderm and the ectoderm. the inner layer of cells, which develops into digestive and respiratory systems. (See 101) |
Endoplasmic reticulum |
Makes lipids, breaks down drugs and other substances, and packages proteins for the Endoplasmic reticulum is a network of tubules, vesicles and sacs that are interconnected. They may serve specialized functions in the cell including protein synthesis, sequestration of calcium, production of steroids, storage and production of glycogen, and insertion of membrane proteins. www.cellbio.utmb.edu/cellbio/rer1.html |
eukaryotic |
descriptive of organisms with cells having a distinct nucleus with nDNA, and intracellular membranes. This includes all protists, fungi, plants and animals. The organisms are termed eucaryotes Literally "true nucleus", the term applies to all protists, plants, animals, and fungi. Eukaryotic cells have internal membranes which partition them into regions for different functions, such as mitochondria, plastids, the ER, Golgi apparatus, etc. They also possess a cytoskeleton which helps them control their shape. |
exocytosis |
a process of cellular secretion or excretion in which substances contained in vesicles are discharged from the cell by fusion of the vesicular membrane with the outer cell membrane. Exocytosis is the process of a biological cell releasing substances into the extracellular fluid (its environment). Exocytosis is the opposite of endocytosis.Vesicles that contain the substances to be released are transported to the plasma membrane and fuse with it. This accomplishes three tasks:# The total surface of the plasma membrane increases (by the surface of the fused vesicle). This is important for the regulation of cell size, e.g., during cell growth. ... |
(physics) the influence that produces a change in a physical quantity; "force equals mass times acceleration" The product of mass (m) and acceleration (a), measured in newtons (nt); thought of as the cause of motion in classical dynamics; that quantity which equals ma in Newton's equation of motion; e.g., gravitational force or the Lorentz force law. Newton's law of acceleration is used to derive the units of force. With the formula F = Ma in the cgs system, one dyne is the force needed for an acceleration of one centimeter per second per second with a mass of one gram. In the mks and SI systems, one newton is the force needed for an acceleration of one meter per second per second with a mass of one kilogram. One newton equals 105 dyne. To convert to English units, 1 N = 0.225 lb. |
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| friction | Friction is a force that resists the motion of an object. Friction results from the close interaction between two surfaces that are sliding across each other. When you slam on your brakes and your car skids to a stop with locked wheels, it is the force of friction that brings it to a stop. Friction resists the car's motion. A force that resists motion between two objects in contact. Friction results in the conversion of mechanical energy into waste heat that dissipates into the surrounding environment. |
A system of about 100 billion stars. Our Sun is a member of the Milky Way Galaxy, which is sometimes just designated by capitalization: Galaxy. There are billions of galaxies in the observable universe. Exactly when and how galaxies formed in the Universe is a topic of current astronomical research. A galaxy is made up of billions or trillions of stars bound together by their own gravity. All of the stars we see in our night sky belong to our own Milky Way galaxy. Most galaxies external to our own require a telescope or photography to see clearly. There are some exceptions; most notable are the Large and Small Magellanic Clouds (visible from the southern hemisphere) and the Andromeda Galaxy -- all of which are visible to the naked eye. |
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| galaxy - elliptical | An elliptical galaxy is a type of galaxy in the Hubble sequence characterized by the following physical properties: * No or at most inconsiderable amount of angular momentum.* No or at most inconsiderable amount of interstellar matter, no young stars, no open star clusters* Consisted of old, so-called Population II stars* Larger elliptical galaxies typically have a system of globular clusters Category of galaxy in which the stars are distributed in an elliptical shape on the sky, ranging from highly elongated to nearly circular in appearance. |
| galaxy - irregular | A galaxy which does not fit into any of the other major categories in the Hubble classification scheme. A strangely shaped galaxy, often rich in interstellar matter, but apparently not a member of any of the major classes of spiral or elliptical galaxies. |
| galaxy - spherical | Galactic Clusters and Massive Spherical GalaxiesThe Ball-of-Light Particle Model predicts there are galactic clusters because one large ball-of-light decaying into smaller balls-of-light. At the center of many Galactic Clusters is found a massive spherical galaxy. The Ball-of-Light Particle Model predicts this is what is left over of the parent ball-of-light. |
| galaxy - spiral | A spiral galaxy is a type of galaxy in the Hubble sequence which is characterizedby the following physical properties: * A considerable total angular momentum* Composed of a central bulge surrounded by a disk ** The bulge resembles an elliptical galaxy, containing many old, so-called "Population II" stars, and usually a supermassive black hole at its center.** The disk is a flat, rotating assembly consisting of interstellar matter, young "Population I" stars and open star clusters. Galaxy composed of a flattened, star-forming disk component which may have spiral arms and a large central galactic bulge. |
gametes
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The reproductive cells in multicellular organisms. Also called germ cells. |
| gamma rays | A very high energy form of radiation similar to X-rays emitted from the nucleus of an atom that can penetrate steel and concrete. (of Radiation): Electromagnetic radiation of high photon energy originating in atomic nuclei and accompanying many nuclear reactions (eg, fission, radioactivity, and neutron capture). Physically, gamma rays are identical with x-rays of high energy, the only essential difference being x-rays do not originate from atomic nuclei, but are produced in other ways (eg, by slowing down (fast) electrons of high energy). See x-rays. ... |
gene |
the unit of heredity. A gene contains hereditary information encoded in the form of DNA and is located at a specific position on a chromosome in a cell's nucleus. Genes determine many aspects of anatomy and physiology by controlling the production of proteins. Each individual has a unique sequence of genes, or genetic code. -- Basic unit of hereditary information. A gene consists of a DNA segment, which includes information for the synthesis of RNA. In some cases this RNA itself is the final product. However, it is mostly used for the transport of genetic information to the ribosomes, where proteins are then assembled |
gene expression |
A gene’s instructions for making a protein are coded in the sequence of nucleotides in the gene. The instructions for making a protein are transferred from a gene to an RNA molecule during transcription. Amino acids are joined together into specific proteins during translation. This process is known as gene expression. www.studyisland.com |
Genetics |
The study of heredity and how traits are passed on through generations www.stanford.edu/group/hopes/sttools/gloss/g.html Study of the patterns of inheritance of genetic information in organisms. |
genotype |
The genetic make-up of an individual organism. |
| globular cluster | A ball of a few hundred thousand stars that resides in the halo of our galaxy and other galaxies. These clusters contain stars that evolve separately from galactic stars; thus, globular clusters hold the original recipe of the galaxy. About 250 globular clusters form a spherical halo around our galaxy. M13, a bright globular cluster in Hercules, is a classic example easily seen with binoculars or a small telescope. Tightly bound, roughly spherical collection of hundreds of thousands, and sometimes millions, of stars, spanning about 50 parsecs. Globular clusters are distributed in the halos around the Milky Way and other galaxies. |
glucose |
a simple sugar made by the body from carbohydrates in food. Glucose is the body's main source of energy. |
Golgi complex |
Processes and transports proteins and other materials out of the cell ( www.studyisland.com) The Golgi complex or Golgi apparatus is responsible for manufacturing, warehousing and shipping certain cellular products, particularly those from the endoplasmic reticulum (ER). Depending on the type of cell, there can be just a few complexes or there can be hundreds. Cells that specialize in secreting various substances typically have a high number of Golgi complexes. biology.about.com/library/weekly/aa042000a.htm |
| gravitation | gravity: (physics) the force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface; "the more remote the body the less the gravity"; "the gravitation between two bodies is proportional to the product of their masses and inversely proportional to the square of the distance between them"; "gravitation cannot be held responsible for people falling in love"--Albert Einstein wordnet.princeton.edu/perl/webwn |
Guanine |
A nitrogenous base, one member of the base pair GC (guanine and cytosine) in DNA. See also: base pair, nucleotide www.ornl.gov/TechResources/Human_Genome/glossary/glossary.html |
-- an inherited bleeding disorder caused by low levels, or absence of, a blood protein that is essential for clotting; hemophilia A is caused by a lack of the blood clotting protein factor VIII; hemophilia B is caused by a deficiency of factor IX. |
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heterozygous |
Producing two gamete types with respect to at least one gene (A/a). www.informatics.jax.org/mgihome/other/glossary.shtml -- having different alleles at the same locus on a chromosome; a recessive and a dominant are paired (so the dominant trait is observed). |
homeostasis |
The state of sustained equilibrium in which all cells, and all life forms, exist. (According to the "strong" Gaia hypothesis, the atmosphere/biosphere system also exists in homeostasis.) An organism in homeostasis adapts to changed environmental conditions by adjusting its own internal state; for example, cold-blooded animals. and warm-blooded animals that hibernate. adjust to colder temperatures by changing their own internal temperature, so that their entire system may remain in homeostasis (Source: Mintzer, 1992). Homeostasis is the physiological process by which the internal systems of the body (e.g. blood pressure, body temperature, acid-base balance) are maintained at equilibrium despite variations in the external conditions. |
Hydrogen bond |
-- a special type of intermolecular interaction whereby the hydrogen of one molecule is attracted to the oxygen, nitrogen, or flourine of another molecule (if the molecule is large enough to fold on itself, this attraction can be between the hydrogen of one molecule and an oxygen, nitrogen or flourine of the same molecule). This interaction will increase the overall stability of the substance or molecule. |
A wave interaction that occurs when two or more waves overlap. |
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| Interphase | The period in the cell cycle when DNA is replicated in the nucleus; followed by mitosis. Interphase is a phase of the cell cycle, defined only by the absence of cell division. Cells during interphase may or may not be growing. At any given time, even in an area of rapid cell division such as the tip of a plant root, 90 per cent of cells are in interphase. Some cells, such as nerve cells, can stay in interphase for decades. The cell grows and replicates its DNA and centrioles. ... |
insulin |
A peptide hormone secreted by the islets of Langerhans of the pancreas that regulates the level of sugar in the blood. a hormone that helps the body use glucose for energy. The beta cells of the pancreas make insulin. When the body cannot make enough insulin, insulin is taken by injection or through use of an insulin pump. |
ion |
An ion is an atom that has been charged. Neutral atoms have the same number of protons and electrons. Since the charge of these two particles are equal in magnitude and opposite in sign, the charge of a neutral atom is zero. When an atom gives up or takes on an electron, the positive and negative charges are no longer balanced. Extra electrons give an ion a negative charge. Fewer electrons give an ion a positive charge. ( www.studyisland.com) An atom or molecule which has gained or lost one or more electrons, thereby having a net negative or positive electrical charge. A fusion plasma is so hot that virtually all the electrons are stripped from the atoms creating ions that have a net positive charge equal to the number of protons in their nucleus. |
isotope |
Isotopes of atoms are atoms with the same number of protons and electrons but different number of neutrons. Adding neutrons to atoms does not affect charge, but it will affect atomic mass. This is why atomic mass is not reported as a whole number on the periodic table. Elements exist as a group of different isotopes. ( www.studyisland.com) Two nuclei of the same element which have the same atomic number but different masses. They contain the same number of protons but a different number of neutrons. Uranium-238 contains 92 protons and 146 neutrons while the isotope U-235 contains 92 protons and 143 neutrons. Thus the atomic weight (atomic mass) of U-238 is three higher than of U-235. |
In a longitudinal wave the particle displacement is parallel to the direction of wave propagation. There are two basic types of wave motion for mechanical waves: longitudinal waves and transverse waves. http://www.kettering.edu/~drussell/Demos/waves/wavemotion.html |
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lysosome |
a cell organelle that serves as recycling and disposal center for the cell. www.vaults.arc.ucla.edu/non_sci/definitions.htm A membrane-bound sac within the cytoplasm of animal cells that contains enzymes responsible for the digestion of material in food vacuoles, the dissolution of foreign particles entering the cell and, on the death of the cell, the breaking down of all cell structures. The digestive system of the cell. |
In physics, magnetism is a phenomenon by which materials exert an attractive or repulsive force on other materials. Some well known materials that exhibit easily detectable magnetic properties are iron, some steels, and the mineral lodestone; however, all materials are influenced to one degree or another by the presence of a magnetic field, although in most cases the influence is too small to detect without special equipment. the force of attraction between an object and a magnet, which pulls the object toward the magnet. |
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meiosis
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the cell division process that eggs and sperm go through which halves the chromosome number from 46 to 23. A special type of cell division that occurs when mature eggs and sperm are formed. Through the process of meiosis the number of chromosomes present in a cell is decreased by half. In humans the diploid number of chromosomes is 46. This is decreased to 23 during meiosis. |
mesoderm |
The middle of the three germ layers of an embryo that forms the connective, musculoskeletal, and vascular tissue. the middle layer of cells, which becomes the circulatory system, bones, muscles, excretory system, and reproductive system. (See 101) |
mitochondria |
Mitochondia are often referred to as the main power source of a cell. That is because of mitochondria's ability to break down glucose and other food molecules to produce energy. The energy released by mitochondria is stored in an ATP molecule. ( www.studyisland.com) A self-replicating organelle bound by two bilayer membranes that is found in the cytoplasm of eukaryotic cells. Mitochondria produce ATP via oxidative phosphorylation reactions carried out by respiratory enzymes located in the inner membrane. Complex organelle found in most eukaryotes; believed to be descended from free- living bacteria that established a symbiotic relationship with a primitive eukaryote. Mitochondria are the site of most of the energy production in most eukaryotes; they require oxygen to function. See: double membrane. |
mitosis |
The process of nuclear division in cells that produces daughter cells that are genetically identical to each other and to the parent cell. See also: meiosis www.ornl.gov/TechResources/Human_Genome/glossary/glossary.html a reproductive process in cells that ultimately results in one cell dividing into two new cells, both identical to the original. The two new cells are called daughter cells. |
multiple sclerosis |
A disease in which there are foci of demyelination of various sizes throughout the white matter of the central nervous system, sometimes extending into the gray matter. Typically, the symptoms of lesions of the white matter are weakness, incoordination, paresthesias, speech disturbances, and visual complaints. The course of the disease is usually prolonged, so that the term multiple also refers to remissions and relapses that occur over a period of many years. The etiology is unknown. (Dorland, 28th ed) -- disease of the brain and spinal cord caused by an unknown agent that gradually destroys the myelin covering, or sheath, of nerve fibers, resulting in a temporary interruption or disordered transmission of nerve impulses, particularly in pathways concerned with vision, sensation, and the use of limbs; disruption of impulse transmission may cause mild to moderate symptoms (numbness in the limbs to complete and permanent paralysis); onset generally occurs between ages 20 and 40, with symptoms appearing at irregular intervals for years |
mutation |
An error in replication or other alteration of the nucleotide base sequence creating a change in the sequence of base pairs on a DNA molecule. If the change occurs in the DNA of a somatic cell, the mutation may cause a change in the organism's phenotype (leading, for example, to cancer) but will not affect the organism's offspring; only mutations in the germ cells can cause heritable changes in the offspring. |
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The term originally applied to any extended (ie, fuzzy, non-stellar) object in the sky. More recently, it is used to describe clouds of gas in space. Some nebulae are illuminated by nearby stars (bright nebulae), while others remain dark and are only seen if they obscure a brighter object (dark nebulae). A cloud of gas and/or dust in interstellar space. (The word nebula in Latin means "cloud"; its plural is "nebulae.'') Nebulae can make themselves apparent by glowing (as "emission nebulae''), by scattering light from stars within them (as "reflection nebulae''), or by blocking light from things behind them (as "obscuration nebulae''). |
nephron
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A tiny part of the kidneys. Each kidney is made up of about 1 million nephrons, which are the working units of the kidneys, removing wastes and extra fluids from the blood. |
neutron |
A neutron is an uncharged particle found in the nucleus of an atom. A neutron, like a proton, contributes one atomic mass unit to the total atomic weight of an atom. ( www.studyisland.com) Neutrons are heavy nuclear particles with no electrical charge and approximately the same mass as protons. With protons, they are the principal components of atomic nuclei. They are composed of two "down" quarks and one "up" quark. |
Newton’s First Law |
An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force. http://www.glenbrook.k12.il.us/gbssci/phys/Class/newtlaws/u2l1a.html |
Newton’s Second Law |
The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. http://www.glenbrook.k12.il.us/gbssci/phys/Class/newtlaws/u2l3a.html |
Newton’s Third Law |
For every action, there is an equal and opposite reaction. http://www.glenbrook.k12.il.us/gbssci/phys/Class/newtlaws/u2l4a.html |
| nuclear fission | The splitting of an atomic nucleus, resulting in the release of large amounts of energy; the basic process a nuclear reactor uses to provide heat for the generation of electricity. (or Fission) - Nuclear fission occurs when a neutron splits the nucleus of a large atom, such as U 235 , into two smaller nuclei, releasing energy and additional neutrons. The extra neutrons then split other nuclei, producing still more neutrons that split more nuclei, and so on. This process is called a nuclear chain reaction. |
| nuclear fusion | is the supposed stellar process by which the nucleii of four hydrogen atoms collide with sufficient energy to coalesce forming a single helium nucleus having slightly less mass than the original hydrogen. The mass which is destroyed in fusion reappears as radiant energy which slowly flows away to the surface. In the fusion, two protons are changed into two neutrons, two anti-electrons, and two neutrinos. ... A way to create energy by combining the nuclei of light atoms into heavier ones. A common example is fusing hydrogen to form helium. The result is slightly less massive than the sum of its parts. This ‘missing mass’ is released as energy. This is the way the Sun produces energy and it could also be a good source of energy here on Earth. Unfortunately, nuclear fusion requires very high temperatures and is difficult to control. |
nucleotide |
A subunit of DNA or RNA consisting of a nitrogenous base (adenine, guanine, thymine, or cytosine in DNA; adenine, guanine, uracil, or cytosine in RNA), a phosphate molecule, and a sugar molecule (deoxyribose in DNA and ribose in RNA). Thousands of nucleotides are linked to form a DNA or RNA molecule. See also: DNA, base pair, RNA www.ornl.gov/TechResources/Human_Genome/glossary/glossary_n.html |
nucleus |
contains the cell's DNA and is the control center of the cell ( www.studyisland.com) a part of the cell containing DNA and RNA and responsible for growth and reproduction |
Small structures inside a cell, generally bounded by membranes. Organelles are independent, distinct , membrane-bounded structures or compartments within a eukaryotic cell which perform specific tasks for the overall success and well being of the cell. The specific funtions of organelles vary widely and typically depend on their proximity within the cell as well as their physical characteristics. |
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oxidation |
Oxidation is the combination of a substance with oxygen. Oxidation can also describe a type of reaction in which the atoms in an element lose electrons and the valence is correspondingly increased. The chemical process of oxygen combining with an element or compound (e.g. the oxidation of iron to form rust). Oxidation is part of the process by which many organisms derive energy from their food: sugars are oxidized in the body to produce energy, water and carbon dioxide. |
The periodic table is a chart of all the known elements in order of increasing atomic number. The table puts elements into groups with similar characteristics, allowing us to recognize trends over the whole array of elements. ( www.studyisland.com) a table in which the elements are commonly arranged in order of increasing atomic number. Elements of similar properties are placed one under the other, yielding eight families or groups of elements. Within each group there is a gradation of chemical and physical properties, but in general a similarity of chemical behavior. From group to group, however, there is a progressive shift of chemical behavior from one end of the table to the other. |
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permeability |
Ability of a membrane or other material to permit a substance to pass through it. |
phagocytes |
Large white blood cells that contribute to the immune defenses by ingesting microbes or other cells and foreign particles. rex.nci.nih.gov/PATIENTS/INFO_TEACHER/bookshelf/NIH_immune/html/imm35.html |
phenotype |
visible characteristics and/or behavior that result from the interaction of an organism's genetic "blueprint" (genotype) and the environment. The observable characteristics of an organism as opposed to the set of genes it possesses (its genotype).The phenotype that an organism manifests is a result of both genetic and environmental factors. Therefore, organisms with the same genotype may display different phenotypes due to environmental factors. Conversely, organisms with the same phenotypes may have different genotypes. |
phosphate group |
Phosphate is a salt of phosphoric acid. Phosphates are extremely important in living cells, particularly in the storage and use of energy and the transmission of genetic information within a cell and from one cell to another. spaceflight.nasa.gov/history/shuttle-mir/references/glossaries/science/sc-gloss-n_s.htm -- One of the molecular components of a nucleotide; a small molecule made up of phosphorus and oxygen. www.stanford.edu/group/hopes/sttools/gloss/p.html |
| photosphere | The layer of the Sun from which all visible light reaches us. The Sun is too hot to have a solid surface and the photosphere consists of a plasma at about 6000 degrees centigrade. The photosphere of an astronomical object is the region at which the optical depth becomes one. In other words, the photosphere is the place where an object stops being transparent. It is typically used to describe the Sun or another star. Because stars are large balls of gas, they have no solid surface. However, there is a depth at which the gas stops being transparent to photons, and this depth provides a visual surface to the star. |
photosynthesis |
The manufacture by plants of carbohydrates and oxygen from carbon dioxide and water in the presence of chlorophyll with sunlight as the energy source. Oxygen and water vapor are released in the process. Photosynthesis is dependent on favorable temperature and moisture conditions as well as on the atmospheric carbon dioxide concentration. Increased levels of carbon dioxide can increase net photosynthesis in many plants (Source: Carbon Dioxide Information Analysis Center, 1990). |
| planetesimals | In cosmogony, planetesimals are objects thought to exist within solar nebulae. Planetesimals are thought to form from the coalescing (due to collisional sticking and gravity) of particles, orbiting within the accretion disc of the solar nebula; an accumulation of planetesimals leads to the formation of a protoplanetary disc, which in turn coalesce into protoplanets/planets. ... basic building blocks that form planets. |
plastid |
a membrane-bound organelle in plant cells that functions in storage (of food or pigments) or food production. Chloroplasts contain the pigments for photosynthesis structures within cells that perform photosynthesis or store starch |
Polarization (waves) |
The process of changing unpolarized waves into polarized waves, or waves that vibrate on only one plane. A light wave is an electromagnetic wave which travels through the vacuum of outer space. Light waves are produced by vibrating electric charges. It is possible to transform unpolarized light into polarized light. Polarized light waves are light waves in which the vibrations occur in a single plane. The process of transforming unpolarized light into polarized light is known as polarization. There are a variety of methods of polarizing light. The four methods discussed on this page are : |
Polygenic inheritance |
Controlled by or associated with more than one gene. www.biotechwithitaly.com/nw_glossary_pr.html -- of or relating to an inheritable character that is controlled by several genes at once; of or related to or determined by polygenes |
Polymerase |
an enzyme which assembles nucleic acid residues into DNA or RNA polymers. Polymerases work from the DNA complement of the sequence to be built. DNA polymerases copy DNA to DNA to replicate the genome before mitosis, while RNA polymerases copy DNA to RNA as the first step in gene transcription. www.cs.wustl.edu/~jbuhler/research/array/glossary.html |
protein |
-- A large molecule composed of one or more chains of amino acids in a specific order; the order is determined by the base sequence of nucleotides in the gene that codes for the protein. Proteins are required for the structure, function, and regulation of the body's cells, tissues, and organs; and each protein has unique functions. Examples are hormones, enzymes, and antibodies. www.ornl.gov/TechResources/Human_Genome/glossary/glossary_p.html -- A complex biological molecule composed of a chain of units called amino acids. Proteins have many different functions: structure(collagen); movement (actin and myosin); catalysis (enzymes); transport (hemoglobin); regulation of cellular processes (insulin); and response to the stimuli (receptor proteins on surface of all cells).The information for making proteins is stored in the sequence of nucleotides in the DNA molecule. |
proton |
A proton is a positively charged particle found in the nucleus of an atom. A proton contributes one atomic mass unit to the total atomic weight of an atom. ( www.studyisland.com) One of the basic particles that makes up an atom. The proton is found in the nucleus and has a positive electrical charge equal to the negative charge of an electron and a mass similar to that of a neutron: a hydrogen nucleus. Protons are heavy nuclear particles carrying a positive electrical charge. Along with neutrons, they are the principal components of atomic nuclei. It has a mass of 1.67 x 10-24 grams, 1836 times the mass of an electron. Protons are composed of two "up" quarks and one "down" quark. |
| pulsar | A rotating neutron star that generates regular pulses of radiation at its spin rate. Pulsars were discovered by observations at radio wavelengths but have since been observed at optical, X-ray, and gamma-ray energies. The term comes from "pulsating radio source" since they were first observed at radio frequencies. Pulsars may be divided in three groups: rotation-powered pulsars, accretion-powered pulsars, and nuclear-powered pulsars. A neutron star that puts out pulses of radio energy. A pulsar is a neutron star that is emitting a beam of radio waves, and spinning, and so the effect is like that of a lighthouse. Pulsars keep exceptionally good time. Most of them ‘pulse’ at a rate between ten times a second and once every three seconds; some spin around hundreds of times a second. |
One of a class of very distant (typically billions of light-years away), extremely bright, and very small objects. The term "quasar'' means "quasi-star'' — that is, something that looks like a star but can't actually be a star. A typical quasar produces more light each second than an entire galaxy of stars does, and it does so from a region of space which is perhaps as small as our solar system. ... The brightest type of active galactic nucleus, believed to be powered by a supermassive black hole. The word “quasar” is derived from quasi-stellar radio source, because this type of object was first identified as a kind of radio source. Quasars also are called quasi-stellar objects (QSOs). Thousands of quasars have been observed, all at extreme distances from our galaxy. |
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All forms of radiation have been linked to DNA mutations. These mutations can lead to cancer. The most common form of radiation that humans are exposed to is UV radiation from the sun. This form of radiation has been linked to skin cancer. www.studyisland.com |
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Reflection (waves) |
When light rays 'bounce' off the surface of an object they are reflected. Waves bounce off a surface at the same angle they hit the surface. The reflection of light is often discussed using phrases such as "a ray of light bounces off of a mirror." This is because when a light ray reflects at the surface of a mirror it follows a path similar in behavior to a pool ball bouncing off of a cushion on a pool table. However unusual it may sound at first, it is not really the best idea to describe the reflection of a light ray using words like bounce. It is better to describe light ray reflection as the turning back of the ray when it encounters the edge of a medium. Light rays, at least at first study, are best not quickly described in terms of particles, say, like pool balls. http://id.mind.net/~zona/mstm/physics/light/rayOptics/reflection/reflection1.html |
Refraction (waves) |
The bending of light as it passes between two substances of different densities is called refraction. Refraction occurs because light travels through different substances at different speeds. If you have ever half submerged a straight stick into water, you have probably noticed that the stick appears bent at the point it enters the water. This optical effect is due to refraction. As light passes from one transparent medium to another, it changes speed, and bends. How much this happens depends on the refractive index of the mediums and the angle between the light ray and the line perpendicular (normal) to the surface separating the two mediums (medium/medium interface). Each medium has a different refractive index. The angle between the light ray and the normal as it leaves a medium is called the angle of incidence. The angle between the light ray and the normal as it enters a medium is called the angle of refraction. http://www.ps.missouri.edu/rickspage/refract/refraction.html |
Resonance (waves) |
What occurs when an object vibrating at or near a resonant frequency of a second object causes the second object to vibrate. This is the vibration frequency of a rotating or moving object. When the resonance of many parts of a machine are in synch, the whole machine will vibrate at a greater rate. This can cause vibration damage. Resonance can cause difficulties in an aircraft, particularly when using a vibration mount with an improperly balanced propeller/spinner wherein the engine is vibrating at one frequency and the propeller at another. |
ribosomes |
Small cellular components composed of specialized ribosomal RNA and protein; site of protein synthesis. See also: RNA www.ornl.gov/TechResources/Human_Genome/glossary/glossary.html Small organelles made of rRNA and protein in the cytoplasm of prokaryotic and eukaryotic cells; aid in the production of proteins on the rough endoplasmic reticulum and ribosome complexes. The site of protein synthesis. The ribosome is composed of two subunits that attach to the mRNA at the beginning of protein synthesis and detach when the polypeptide has been translated. |
RNA |
-- a single-stranded nucleic acid made up of nucleotides. RNA is involved in the transcription of genetic information; the information encoded in DNA is translated into messenger RNA (mRNA), which controls the synthesis of new proteins. www.sfaf.org/treatment/beta/b32/b32glos.html -- A chemical found in the nucleus and cytoplasm of cells; it plays an important role in protein synthesis and other chemical activities of the cell. The structure of RNA is similar to that of DNA. There are several classes of RNA molecules, including messenger RNA, transfer RNA, ribosomal RNA, and other small RNAs, each serving a different purpose. www.ornl.gov/TechResources/Human_Genome/glossary/glossary_r.html |
-- an inherited autosomal recessive condition that causes abnormal hemoglobin in blood cells, leading to infections and organ damage. www.chkd.com/Genetics/glossary.asp -- an inherited blood disorder characterized by defective hemoglobin, where there are two copies of an abnormal hemoglobin gene present (HbSS). |
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somatic cells |
Any cell in the body except gametes and their precursors. |
| SUN (Sol) - energy - time from core to surface | Solar energy is created deep within the core of the Sun. It is here that the temperature (15,000,000° C; 27,000,000° F) and pressure (340 billion times Earth's air pressure at sea level) is so intense that nuclear reactions take place. Energy generated in the Sun's core takes a million years to reach its surface. |
A nitrogenous base, one member of the base pair AT (adenine-thymine). See also: base pair, nucleotide www.ornl.gov/TechResources/Human_Genome/glossary/glossary_t.html |
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transcription |
(genetics) the organic process whereby the DNA sequence in a gene is copied into mRNA; the process whereby a base sequence of messenger RNA is synthesized on a template of complementary DNA |
transpiration |
The process in plants by which water is taken up by the roots and released as water vapor by the leaves. The term can also be applied to the quantity of water thus dissipated (Source: Carbon Dioxide Information Analysis Center, 1990). |
Transverse wave |
In a transverse wave the particle displacement is perpendicular to the direction of wave propagation. The particles do not move along with the wave; they simply oscillate up and down about their individual equilibrium positions as the wave passes by. http://www.kettering.edu/~drussell/Demos/waves/wavemotion.html |
Trophic level |
A segment of the food chain in which all organisms obtain food and energy in, basically, the same manner (e.g., photosynthesis, herbivory, or carnivory) and in which all organisms are the same number of links from the photosynthetic segment (Source: Carbon Dioxide Information Analysis Center, 1990). A number indicating the position of a species within an ecosystem. By definition, plants have a TL = 1, herbivores TL = 2, and so on, up to a TL = 5 in killer whales and polar bears. Note that trophic levels do not need to be whole numbers; intermediate values occur among fishes and other animals with a mixed diet composition. The phrase "fishing down marine food webs" refers to the increased tendency for marine landings to consist of animals with lower trophic levels. |
Nucleotide base normally found in RNA but not DNA; uracil can form a base pair with adenine. home.san.rr.com/dna/darryl/glossary.html |
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stores water and other materials ( www.studyisland.com) Membrane-bound fluid-filled space within a cell. In most plant cells, there is a single large vacuole filling most of the cell's volume. Some bacterial cells contain gas vacuoles. A cellular organelle that is used for the storage of any number of compounds, including food, water and waste. |
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valence |
(chemistry) a property of atoms or radicals; their combining power given in terms of the number of hydrogen atoms (or the equivalent) In °covalent compounds, the valence of an atom is the number of bonds it forms to other atoms. |
A WAVE is any disturbance that transmits energy through matter or space. Some types of waves, such as electromagnetic waves, can also radiate energy. Types of waves include: transverse waves, longitudinal waves, and surface waves. |
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a fertilized egg with the diploid number of chromosomes formed by the union of the nuclei of male and female gametes The joined sperm and egg from the moment of conception until the time it "beds" into the wall of the womb and develops an umbilical cord. |
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The cloud model represents a sort of history of where the electron has probably been and where it is likely to be going. The red dot in the middle represents the nucleus while the red dot around the outside represents an instance of the electron. Imagine, as the electron moves it leaves a trace of where it was. This collection of traces quickly begins to resemble a cloud. The probable locations of the electron predicted by Schrödinger's equation happen to coincide with the locations specified in Bohr's model.