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acid
molecules tending to raise the hydrogen ion concentration in a solution and to lower its pH numerically.
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adenine (A):
one of the four nitrogen bases in nucleotides composing the structure of DNA and RNA.
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ADP (adenosine diphosphate)
nucleotide with two phosphate groups and become ATP.
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amino acid
nucleotide with two phosphate groups that can accept another phosphate group and become ATP.
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atom
smallest particle of an element that displays the properties of the element.
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atomic mass
mass of an atom equal to the number of protons plus the number of neutrons with the nucleus.
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atomic number
number of protons within the nucleus of an atom
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ATP (adenosine triphosphate)
nucleotide with three phosphate groups. the breakdown of ATP into ADP and P makes energy available for energy - requiring processes in cells.
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base
molecules tending to lower the hydrogen ion concentration in a solution and raise the pH numerically.
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buffer
substance or group of substances that tend to resist pH changes of a solution, thus stabilizing its relative acidity and basicity.
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calorie
the amount of heat energy required to raise the temperature of 1 g of water by 1 ^degree C.
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carbohydrate
class of organic compounds that includes monosaccharides, disaccharides, and polysaccharides.
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cellulose
polysaccharide that is the major complex carbohydrate in plant cell walls.
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complementary paired bases
- Hydrogen bonding between particular bases;
- in DNA thymine (T) pairs with adenine (A),
- and guanine (G) pairs with cytosine (C);
- in RNA, uracil (U) pairs with A,
- and G pairs with C.
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compound
substance having two or more different elements united chemically in a fixed ratio.
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covalent bond
chemical bond in which atoms share one pair of electrons.
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cytosine (C)
one of four nitrogen bases in nucleotides composing the structure of DNA and RNA.
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dehydration reaction
chemical reaction resulting in a covalent bond with the accompanying loss of a water molecule
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denaturation
loss of normal shape by an enzyme so that it no longer functions; caused by a less than optimal pH or temperature.
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dissacharide
sugar that contains two units of a monosaccharide (ex: maltose)
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DNA (deoxyribonucleic acid)
nucleic acid polymer produced from covalent bonding of nucleotide monomers that contain the sugar deoxyribose; the genetic material of nearly all organisms.
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electron
negative subatomic particle, moving about in an energy level around the nucleus of an atom.
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element
substance that cannot be broken down into substances with different properties; composed of only one type of atom.
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emulsification
breaking up of fat globules into smaller droplets by the action of bile salts or any other emulsifier.
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fat
organic molecule that contains glycerol and fatty acids; found in adipose tissue.
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fatty acid
molecule that contains a hydrocarbon chain and ends with an acid group/
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glucose
six-carbon sugar that organisms degrade as a source of energy during cellular respiration
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glycogen
storage polysaccharide composed of glucose molecules joined in a linear fashion but having numerous branches.
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guanine (G)
one of four nitrogen-containing bases in nucleotides composing the structure of DNA and RNA; pairs with cytosine.
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hemoglobin
iron-containing pigment in red blood cells that combines with and transports oxygen.
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hydrogen bond
weak bond that arises between a slightly positive hydrogen atom of one molecule and a slightly negative atom of another, or between parts of the same molecule.
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hydrolysis reaction
splitting of a compound by the addition of water, with the H+ being incorporated in one fragment and the OH- in another.
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hydrophilic
type of molecule that interacts with water by dissolving in water and/or foaming hydrogen bonds with water molecules.
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hydrophobic
type of molecule that does not interact with water because it is nonpolar.
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ion
charged particle that carries a negative or positive charge.
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ionic bond
chemical bond in which ions are attracted to one another by opposite charges.
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isotope
one of two or more atoms with the same atomic number but a different atomic mass due to the number of neurons.
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lipid
class of organic compounds that tends to be soluble only in nonpolar solvents, such as alcohol; includes fats and oils.
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macromolecule
extremely large biological molecule; refers specifically to proteins, nucleic acids, polysaccharides, lipids, and complexes of these.
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mass
sum of the number of protons and neutrons in an atom's nucleus.
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mass number
the number of nucleons (protons and neutrons) in the nucleus of an atom.
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matter
anything that takes up space and has mass
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mole
a unit of scientific measurement for atoms, ions, and molecules.
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molecule
union of two or more atoms of the same element; also, the smallest part of a compound that retains the properties of the compound.
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monosaccharide
simple sugar; a carbohydrate that cannot be decomposed by hydrolysis (ex: glucose)
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neutron
neutral subatomic particle, located in the nucleus and having a weight of approximately one atomic mass unit.
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nucleotide
monomer of DNA and RNA consisting of a 5-carbon sugar bonded to a nitrogen-containing base and a phosphate group.
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nucleus
membrane bounded organelle that contains chromosomes and controls the structure and function of the cell.
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oil
substance, usually of plant origin and liquid at room temperature, formed when a glycerol molecule reacts with three fatty acid molecules.
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orbital
pathway in which electrons travel around the nucleus of an atom.
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organic
molecule that always contains carbon and hydrogen, and often contains oxygen as well; organic molecules are associated with living things.
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organic molecule
type of molecule that contains carbon and hydrogen - and often contains oxygen also.
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pentose
five-carbon sugar. deoxyribose is the pentose sugar found in DNA; ribose is a pentose sugar found in RNA.
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peptide bond
type of covalent bond that joins two amino acids.
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pH scale
measurement scale for hydrogen ion concentration
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phospholipid
molecule that forms the bilayer of the cell's membranes; has a polar, hydrophilic head bonded to two nonpolar, hydrophobic tails.
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polar
combination of atoms in which the electrical charge is not distributed symmetrically.
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polypeptide
polymer of many amino acids linked by peptide bonds.
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polysaccharide
polymer made from sugar monomers; the polysaccharides starch and glycogen are polymers of glucose monomers.
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protein
molecule consisting of one or more polypeptides
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proton
positive subatomic particle, located in the nucleus and having a weight of approximately one atomic mass unit.
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radioisotope
unstable form of an atom that spontaneously emits radiation in the form of radioactive particles or radiant energy.
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RNA (ribonucleic acid)
nucleic acid produced from covalent bonding of nucleotide monomers that contain the sugar ribose; occurs in three forms: messenger RNA, ribosomal RNA, and transfer RNA.
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saturated fatty acid
fatty-acid molecule that lacks double bonds between the atoms of its carbon chain
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starch
storage polysaccharide found in plants that is composed of glucose molecules joined in a linear fashion with few side chains.
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steroid
type of lipid molecule having a complex of four carbon rings; examples are cholesterol, progesterone, and testosterone.
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thymine (T)
one of four nitrogen containing bases in nucleotides composing the structure of DNA; pairs with adenine.
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tracer
substance having an attached radioisotope that allows a researcher to track its whereabouts in a biological system.
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trans fat
fats, which occur naturally in meat and dairy products of ruminants, that are also industrially created through partial hydrogenation of plant oils and animal fats.
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trigyceride
neutral fat composed of glycerol and three fatty acids.
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unsaturated fatty acid
fatty-acid molecule that has one or more double bonds between the atoms of its carbon chain.
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uracil (U)
the base in RNA that replaces thymine found in DNA; pairs with adenine.
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