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122 Cards in this Set
- Front
- Back
Acid
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A substance that decreases the pH of a solution.
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Acidosis
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Excess acid in extracellular fluid.
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Activation Energy Barrier
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In order to bond to one another, the two reactants must meet each other with sufficient energy to overcome an activation energy barrier required for a bond to form.
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Active Site
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In the general theory of enzyme catalysis, the tertiary structure of an enzyme forms a pocket in which the reactants are brought in the proper orientation for bond formation.
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Adenine
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A base in DNA.
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Adenosine Diphosphate
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In the process of ATP driving energy-requiring reactions, one of three phosphate groups of ATP is split off, yielding adenosine diphosphate (ADP) and inorganic phosphate (Pi).
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Adenosine Triphosphate
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The main source of energy available to cells to drive energy-requiring reactions and ordinarily would not proceed spontaneously.
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Alkalosis
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Excess base in extracellular fluid.
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Allosteric Phosphorylation
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At another site other than the active site, the attachment of a phosphate group [PO4] at a specific site on the protein by another enzyme, kinase.
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Allosteric Regulation
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Allosteric means "at another site" than the active site. A major principle of enzyme regulation within cells is that the activity of an enzyme can be regulated--increased or decreased, depending on the particular enzyme and binding site--by phosphorylation (attachment of a phosphate group [PO4] at a specific allosteric site on the protein by another enzyme called a kinase). Likewise, some key enzymatic reactions are regulated by allosteric inhibition of the product of the reaction acting on the enzyme.
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Amino Acids
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Organic compounds that contain a least one carbon atom that is bonded simultaneously to carboxyl group; amino group; hydrogen atom; and a side chain of varying of complexity, the structure which determines the type of amino acid. The side chain may be polar, nonpolar, acidic, base, or aromatic.
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Amphiphathic
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A molecule that is most stable when its head is in an aqueous environment and its tail is a nonpolar environment.
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Anabolism
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Energy captured in catabolic processes is used to assemble simple molecules from food into the proteins, nucleic acids, lipids, and other macromolecules needed for cellular growth and maintenance.
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Anion
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In an ionic bond, the acceptor atom that is negatively charged.
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Atomic Number
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The number of protons in the nucleus of atom that establishes the chemical identity of the at atom.
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Atomic Weight
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The sum of the numbers of protons and neutrons in the nucleus.
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Atoms
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The basic units of all matter.
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Avogadro's Number
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No matter what the compund, one mole contains on Avogadro's number (6.023 x 10 to 23rd) of molecules.
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Base
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A substance that increases the pH of a solution.
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Buffer
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A system of reactants that acts to minimize changes in pH.
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Catabolism
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A series of reactions in which the cell extracts energy from chemical sources in the environment. The term catabolism also includes reactions that convert complex molecules from the food into simple ones that can be used to construct new molecules needed by the cell.
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Catalysts
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Substances that promote reactions by lowering their activation energy barriers without themselves being changed in the reaction.
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Cation
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In an ionic bond, the donor atom is positively charged.
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Cellular Respiration
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An oxidation process in which ATP used in cellular activities is rapidly regenerated by the cell's energy metabolism.
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Chemical Bond
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Forms when there is interaction between the orbitals of the outermost energy levels of two atoms.
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Chemical Reactions
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Processes that form or break chemical bonds, resulting in the formation of new compounds.
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Chromosome
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A nucleus structure consisting of a double strand of DNA together with a large number of associated smaller molecules that are involved in regulation of gene expression and chromosomal structure.
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Colloid
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A suspension whose particles are so small that intermolecular forces can overcome that force of gravity and keep the particle suspended.
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Compounds
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Substances composed of two or more elements.
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Covalent Bonds
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The strongest form of atomic bonding in which the bonded partners share one or more electrons to complete their outer energy levels.
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Cytosine
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A base in DNA.
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Decomposition Reactions
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The opposite of synthesis reactions, taking the form AB -> A + B.
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Dehydration Reaction
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A reaction in which the removal of a H+ from one reactant and OH- from the other simultaneously allows the formation of a molecule of water and a bond between the two reactants, creating disaccharides from monosaccharides.
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Denatured
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When the tertiary structure of enzymes begins to unravel.
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Dipole
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Atoms connected by a polar bond.
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Disaccharides
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Formed from monosaccharides by a dehydration reaction.
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DNA
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Deoxyribonucleic acid. One type of nucleic acid in which tow polynucleotide strands are twined into a double helix. It is the form in which information about the primary sequences of proteins is passed to daughter cells in cell division during growth and development and in formation of reproductive cells in the gonads.
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Electrolytes
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Compounds that incorporate ionic bonds are typically separated into their component ions in water solution.
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Electron Acceptors
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Those atoms with nearly full outer levels tend to acquire electrons to fill their orbitals.
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Electron Donors
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Those atoms that are from having a filled outer level can find stability most easily by moving in the direction of emptying their outermost energy levels.
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Energy Level
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An electron orbital arranged around the nucleus of an atom.
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Enzyme
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A protein that acts as the body's catalysts, permitting it to carry out a body temperature reactions that would require a much higher temperature if conducted without catalysis.
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Equilibrium
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When the relative concentrations of reactants and product will have changed such that the reverse reaction goes as rapidly as the forward reaction.
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Equilibrium Constant (Keq)
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The characteristic ratio of reactants to product at equilibrium.
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Equivalent (Eq)
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Expressing solute concentrations as a measure of the number of charges per unit of volume rather than the number of particles.
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Exons
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The pieces of RNA that remain after editing that are spliced back together during posttranscriptional processing.
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Fatty Acids
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Chains of carbons terminating in a carboxyl group.
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Gametes
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Reproductive Cells
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Glycogen
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A polysaccharide that has an important role as an energy store within cells.
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Glycolipids
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Lipids with covalently bound carbohydrates--the bound carbohydrate chain may be from one to seven or more monosaccharides long.
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Guanine
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A base in DNA.
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Haploid
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A reproductive cell that has twenty-two somatic chromosomes and either an X or Y chromosome.
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Homologous Pairs
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Present in all cells except gametes; the members of each pair are similar in size and contain genes that are related, but not necessarily identical.
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Hydration Shell
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An ionic solution surrounded by a shell of water molecules oriented with their electrically opposite poles towards the ion.
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Hydrogen Bonds
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The result of the fact that hydrogen-nitrogen and hydrogen-oxygen bonds are polar covalent bonds. A hydrogen so bonded has a small positive charge because the electron it is sharing spends most of its time with the oxygen or nitrogen.
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Inducers
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Remove repressors and prevent their binding to the DNA.
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Introns
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Parts that will be edited and not appear in the final RNA transcript.
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Ionic Bond
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Formed when an element that readily gives up electrons reacts with an element that readily accepts them. The result is that one or more electrons are transferred from the donor to the acceptor.
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Isoform
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Enzymes that exist in multiple forms with different enzymatic properties, and are the products of separate genes. Tissues may express one specific isoform or may generate a mixture of isoforms.
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Isomer
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Different forms of molecules with the same chemical formula.
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Isotope
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Different forms of the same element having the same number of protons but differing in the number of neutrons.
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Isozyme
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Enzymes that exist in multiple forms with different enzymatic properties
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Kinase
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An enzyme.
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Lipids
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The major nonpolar, water-insoluble organic molecules in the body.
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Lysosomes
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Digest condemned proteins within the endocytotic vesicle, making the proteins' component of amino acids available for reuse.
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Meiosis
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The formation of reproductive cells in the gonads.
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Micelles
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Phospholipid bilayers.
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Mitochondrion
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A cellular organelle.
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Molarity
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For a solution, the number of grams of a solute per liter (l) of water, divided by the solute's molecular weight.
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Molecular Weight
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The total of all of the atomic weights of its components expressed in grams.
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Molecules
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Structures that result from attachment of atoms to one another by chemical bonds.
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Monosaccharides
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Molecules that contain six carbons arranged in a six-sided ring (hexoses) or a five-side (pentoses). Monosaccharides are one of the chief starting materials for energy metabolism since they can be oxidized with release of considerable energy.
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Motifs
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Within the secondary structure proteins, established by folding, coiling, or pleating the chain at particular regions of the primary sequence to form characteristic simple shapes. These effects are primarily due to the formation of hydrogen bonds and van der Waals interactions between different parts of the primary structure.
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mRNA
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Messenger RNA. Carries the information for protein sequences from the nucleus to the protein synthesis machinery in the cytoplasm.
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Neutrons
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Uncharged particles in the nucleus of the atom.
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Nonpolar Bond
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A covalent bond resulting from bonded atoms with equally strong electron donors and acceptors: each shared electron spends about the same amount of time with each of the two bonded atoms.
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Nucleic Acids
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Linear chains of nucleotides strung together in a sequence that carries information (DNA and RNA).
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Nucleotides
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Molecules consisting of a five-carbon sugar (which is deoxyribose in DNA and ribose in RNA), a phosphate group, and a nitrogen-containing aromatic base.
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Nucleus
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In the atom, it contains a variable number of protons and neutrons.
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Orbitals
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Spaces in which there is 90% probability of finding a particular electron at any particular instant. Each orbital is full when it contains 2 electrons.
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Organic
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Compounds that contain carbon and hydrogen.
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Oxidized
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In redox reactions, one atom donates one or more electrons to another atom. The donor atom becomes oxidized, and the recipient becomes reduced. Such reactions are important in the energy metabolism of cells because, in many cases, the chemical energy potential of foodstuffs is due to their ability to release energy when they are oxidized.
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Peptide Bonds
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Join proteins in chains of amino acids. Formation of a peptide bond is a dehydration reaction.
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pH
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Pure water at standard temperature has hydrogen and hydroxyl ion concentrations of 10 to -7 mEq/l each. It is convenient to express hydrogen ion concentration as a logarithm: log (1/[H+]}. This results in a pH scale that runs from 1 - 14.
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Phospholipids
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Major components of the plasma membrane surrounding cells and of other membranes within the cellular interior. They are the result of replacing one of the fatty acids of a triacylglycerol with a phosphate group bound to a polar molecule.
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Polysaccharides
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Chains of sugars, such as a starch and glycogen.
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Posttranscriptional Processing
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In the first step of gene expression, the two-stranded DNA is unwound at the appropriate spot and a complementary strand of mRNA is assembled using one of the strands as a template. This process is catalyzed by an enzyme called RNA polymerase. Next, the primary transcript must be edited, for it contains parts, called introns, that will not appear in the final transcript. The pieces of RNA that remain after editing, called exons, are spliced back together.
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Posttranscriptional Processing
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During the translation of the nucleotide sequence into a corresponding amino acid sequence, sometimes part of the amino acid sequence are clipped off or two or more polypetides are attached together to form a functional complex.
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Primary Sequence
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The firs, most elementary level in the structure of proteins. This is simply the order of amino acids in the protein chain.
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Primary Transcript
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The working copies of individual sentences that are made in the form of a single strand of complementary messenger RNA (mRNA).
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Products
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In a chemical reaction, elements or compounds that were not present in that form initially.
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Promotor
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Each gene has a promotor sequence at its head end. Transcription of a gene begins when RNA polymerase binds to the promotor side and continues until the polymerase reaches the terminator site. The promotor and terminator sequences simply act to attach and detach the polymerase--they don't get transcribed.
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Prostaglandins
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Derivatives of a arachidonic acid, a twenty-carbon fatty acid.
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Protons
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Positively charged particles in the nucleus of the atom.
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Pulmonary Surfactant
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Secreted by the lungs, interfering with the water-water interactions and reduces surface tension.
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Quarternary Structure
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Fully structured proteins that may associate with one another to form functional units (e.g., the enzyme high-energy particles from their nuclei.
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Receptor
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At the molecular level, this term applies to molecules that recognize signal molecules of specific types and assist in bringing about the signal's effect of the target cells.
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Redox Reaction
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In redox (oxidation-reduction) reactions, one atom donates one or more electrons to another atom. The donor atom becomes oxidized, and the recipient becomes reduced.
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Repressors
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Proteins that may block the attachment of polymerase to the promotor by attaching to the promotor site.
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Ribosomal RNA (mRNA)
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One of three functional classes of RNA, largely composing the ribosomes.
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Ribosome
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Protein synthesizing organelles.
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RNA
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One type of nucleic acid, curled into a single spiral helix, comprising linear chains of nucleotides strung together in a sequence that carries information. In RNA, uracil (U) appears instead of thymidine.
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RNA polymerase
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An enzyme that catalyzes the process in the first step of gene expression: the two-stranded DNA is unwound at the appropriate spot and a complementary strand of mRNA is assembled using one of the strands as a template.
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Rough ER
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An endoplasmic reticulum studded with ribosomes and is a visible sign that the cell is actively synthesizing such proteins.
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Secondary Structure
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In the structure of proteins, this level is established by folding, coiling, or pleating the chain at particular regions of the primary sequence to form characteristic simple shapes (motifs).
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Signal Sequence
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Causes the ribosome translating the mRNA to attach itself to the endoplasmic reticulum.
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Solubility Coefficient
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A measure of the maximum amount of that substance that can be held in solution by a given solute under standard conditions of temperature and pressure.
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Solutes
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Substances that can be dissolved in a solvent.
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Solvent
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A fluid in which other substances (the solutes) can be dissolved.
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Stereoisomers
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Variant forms of molecules that differ in the orientation of a key functional group.
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Substrates
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An enzyme's reactants.
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Suspension
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Particles with dimensions exceeding that of the typical molecule may be dispersed in water.
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Synthetic Reactions
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Combine two or more elements or compounds to form a new compound according to the from A + B = AB.
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Terminator
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Each gene has a terminator sequence at its tail end. Transcription of a gene begins when RNA polymerase binds to the promotor site and continues until the polymerase reaches the terminator site. The promotor and terminator sequences simply act to attach and detach the polymerase--they don't get transcribed.
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Thymine
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A base in DNA.
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Transfer RNA (tRNA)
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Responsible for recognizing particular amino acids and adding them to the growing polypeptide chain in the order specified by the mRNA.
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Triacylglycerols
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The major form of a stereo lipid in the body, making up the majority of the fat in adipose cells.
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Ubiquitin
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A molecule that labels proteins that are to undergo destruction.
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Uracil
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in RNA, a nitrogen-containing aromatic base that appears instead of thymidine (DNA).
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Valence
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The number of electrons an element can accept or donate.
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Valence Electron
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An electron in an outer energy level that an element can donate.
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van der Waals Forces
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Attractive forces that develop between molecules or between different parts of the same large molecule as a result of the fact that the distribution of electrons in each molecule varies over time.
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