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.