Chapter 1: The Chemical Basis of Life Flashcards
Isotopes
Different atoms of the same element containing the same number of protons but a different number of neutrons.
Radioisotopes
Radioactive atoms of an element that spontaneously decay into smaller atoms, subatomic particles, and energy.
Half-Life
The time it takes for one-half of the nuclei in a radioactive sample to decay.
Radioactive Tracers
Radioisotopes that are used to follow chemicals through chemical reactions and trace their path as they move through the cells and bodies of organisms
Orbitals
Volumes of space around the nucleus where electrons are most likely to be found.
Valence Electrons
Electrons located in outermost s and p orbitals that determine an atom’s chemical behavior.
Intramolecular Forces of Attraction
The covalent bond that holds the atoms of a molecule together, and the ionic bond that holds ions together in a salt.
Electronegativity
A measure of an atom’s ability to attract a shared electron pair when it is participating in a covalent bond.
Hybridization
For atoms, a modification of the valence orbitals that changes the orientation of the valence electrons; in genetic coding, complementary base pairing between strands of nucleic acids via hydrogen bonding.
Intermolecular Bonds
Chemical bonds between molecules.
Van der Waals Forces
Intermolecular forces of attraction including London Forces, dipole-dipole forces and hydrogen bonds.
Miscible
Describes liquids that dissolve into one another.
Immiscible
Describes liquids that form separate liquids instead of dissolving.
Hydrophobic
Having an aversion to water; the tendancy of nonpolar molecules to exclude water.
Hydrophilic
Having an affinity to water; the tendency of polar and ionic substances to dissolve in water.
Neutralization Reaction
The reaction of an acid and a base to produce water and salt.
Strong Acids
Acids that ionize completely in aqueous solution.
Strong Bases
Bases that ionize completely in aqueous solution.
Weak Acids
Acids that partially ionize in aqueous solution.
Weak Bases
Bases that partially ionize in aqueous solution.
Equilibrium
A condition in which opposing reactions occur at equal rates.
Buffers
Chemical systems containing a substance that can donate H+ ions when they are required and containing a substance that can remove H+ ions when there are too many in a solution.
Activation Energy
The difference between the energy level of the transition state and the potential energy of reacting molecules.
Activator
A substance that binds to an allosteric site on an enzyme and stabilizes the protein conformation that keeps all the active site available to their substrates.
Active Site
The location where the substrate binds to an enzyme.
Adenosine Triphosphate (ATP)
A nucleotide derivative that acts as the primary energy-transferring molecule in living organisms.
Allosteric Inhibitor
A substance that binds to an allosteric site on an enzyme and stabilizes the inactive form of the enzyme.
Allosteric Sites
Receptor sites, some distance from the active site of certain enzymes, that bind substances that may inhibit or stimulate an enzyme’s activity.
Alpha (α) Helix
A type of polypeptide secondary structure characterized by a tight coil that is stabilized by hydrogen bonds.
Amino Terminus
The free amino group at one end of a polypeptide.
Anabolic Reactions
Reactions that produce large molecules from smaller subunits.
Antiparallel
Describes two adjacent nucleotides running in opposite directions relative to one another.
β-pleated sheet
Polypeptide secondary structures that form between parallel stretches of a polypeptide and are stabilized by hydrogen bonds.
Bond Energy
The minimum energy required to break one mole of bonds between two species of atoms; a measure of the stability of a chemical bond.
Bonding Capacity
The number of covalent bonds an atom can form with neighbouring atoms.
Carboxyl Terminus
The free carboxyl group at one end of a polypeptide.
Catabolic Reactions
Reactions that break macromolecules into their individual subunits.
Chaperone Proteins
Special proteins that aid a growing polypeptide to fold into tertiary structure.
Coenzymes
Organic nonprotein cofactors that are needed for some enzymes to function.
Cofactors
Nonprotein components, such as dissolved ions, that are needed for some enzymes to function.
Competitive Inhibitors
Substances that compete with the substrate for an enzyme’s active site.
Condensation Reaction
dehydration synthesis
A reaction that creates a covalent bond between two interacting subunits,linking them to each other.
Conformation
The three-dimensional shape of a protein determined by the sequence of amino acids it contains.
Disulfide Bridge
Covalent bonds between cysteine residues in a polypeptide that stabilize tertiary structure.
Endergonic Reaction
A chemical reaction in which the energy of the products is more than the energy of the reactants; chemists call it an endothermic reaction.
Energy
The ability to do work.
Entropy
A measure of the randomness or disorder in a collection of objects or energy; symbolized by S.
Enzyme–Substrate Complex
An enzyme with its substrate attached to the active site.
Essential Amino Acids
Amino acids that the body cannot synthesize from simpler compounds; they must be obtained from the diet.
Ester Linkage
A functional group linkage formed by the condensation of a carboxyl group and a hydroxyl group.
Exergonic Reaction
A chemical reaction in which the energy of the products is less than the energy of the reactants; chemists call it an exothermic reaction.
Feedback Inhibition
A method of metabolic control in which a product formed later in a sequence of reactions allosterically inhibits an enzyme that catalyzes a reaction occurring earlier in the process.
Free Energy (Gibbs free energy)
Energy that can do useful work.
Functional Groups
Reactive clusters of atoms attached to the carbon backbone of organic molecules.
Globular Proteins
Protein molecules composed of one or more polypeptide chains that take on a rounded,spherical shape.
Glycosidic Linkages
Covalent bonds holding monosaccharides to one another that are formed by condensation reactions in which the H atom comes from a hydroxyl group of one sugar and the —OH group comes from a hydroxyl group of the other.
Hydrolysis Reaction
A catabolic reaction in which a water molecule is used to break a covalent bond holding subunits together.
Induced-fit Model
A model of enzyme activity that describes an enzyme as a dynamic protein molecule that changes shape to better accommodate the substrate.
Isomers
Molecules with the same chemical formula but with a different arrangement of atoms.
Kinetic Energy
Energy possessed by moving objects.
Macromolecules
Large molecules sometimes composed of a large number of repeating subunit.
Metabolism
The sum of all anabolic and catabolic processes in a cell or organism.
Micelles
Spheres formed when phospholipids are added to water.
Noncompetitive Inhibitors
Substances that attach to a binding site on an enzyme other than the active site,causing a change in the enzyme’s shape and a loss of affinity for its substrate.
Oligosaccharides
Sugars containing several simple sugars attached to one another.
Oxidation
A chemical reaction in which an atom loses one or more electrons.
Oxidizing Agent
The substance that gains an electron in a redox reaction; the substance that causes the oxidized atom to become oxidized.
Peptide Bonds
The amide linkage that holds amino acids together in polypeptides.
Phosphorylation
The process of attaching a phosphate group to an organic molecule.
Potential Energy
Energy stored by virtue of an object’s position within an attractive or repulsive force field.
Potential Energy Diagram
A diagram showing the changes in potential energy that take place during a chemical reaction.
Primary Structure
The unique sequence of amino acids in a polypeptide chain.
Quaternary Structure
Two or more polypeptide subunits forming a functional protein.
Redox Reaction
A chemical reaction involving the transfer of one or more electrons from one atom to another; a reaction in which oxidation and reduction occur.
Reducing Agent
The substance that loses an electron in a redox reaction; the substance that causes the reduced atom to become reduced.
Reduction
A chemical reaction in which an atom gains one or more electrons.
Residue
An amino acid subunit of a polypeptide.
Secondary Structure
Coils and folds in a polypeptide caused by hydrogen bonds between hydrogen and oxygen atoms near the peptide bonds.
Strand
A single nucleotide polymer.
Substrate
The reactant that an enzyme acts on when it catalyzes a chemical reaction.
Tertiary Structure
Supercoiling of a polypeptide that is stabilized by side-chain interactions,including covalent bonds, such as disulfide bridges.
Transition State
In a chemical reaction,a temporary condition in which the bonds within reactants are breaking and the bonds between products are forming.
Triacylglycerols (triglycerides)
Lipids containing three fatty acids attached to a single molecule of glycerol.
Van der Waals Forces
Intermolecular forces of attraction including London forces,dipole–dipole forces,and hydrogen bonds.
Valence Shell Electron
Electrons located in outermost s and p orbitals that determine an atom’s chemical behaviour.
Valence Shell Electron Pair Repulsion (VSEPR) theory
A method for predicting molecular shape based on the mutual repulsion of valence electron pairs.
Work
The transfer of energy from one body or place to another.
C = O
Carbonyl Group
