BIO - TERMS - ELECTR Flashcards
1,4-Addition
Addition of a reactant to the ends of a conjugated π system. Conjugated dienes yield 1,4 adducts when treated with electrophiles such as HCl. Conjugated enones yield 1,4 adducts when treated with nucleophiles such as amines.
ampere (A)
The SI unit for electrical current; 1 A = 1 C/s.
Antarafacial
A pericyclic reaction that takes place on opposite faces of the two ends of a p electron system.
Antimycin A
An inhibitor of electron flow through the QH2-cytochrome c reductase complex.
bidentate
A term describing ligands that donate two electron pairs to the central metal.
bioelectrical impedance analysis (BIA)
Procedure for assessing body composition in which an electric current is passed through the body. The resistance to current flow reflects the relative amount of fat present.
cathode
The electrode in an electrochemical cell at which reduction occurs; electrons flow toward the cathode.
cathode ray
A stream of electrons produced when a high electrical voltage is applied between two electrodes within a partially evacuated tube.
cathode ray tube
An evacuated tube containing charged plates to accelerate and view electron beams.
cell potential (cell emf) (Ecell)
The potential difference between the cathode and the anode in an electrochemical cell.
complementary properties
Properties that exclude one another; that is, the more you know about one, the less you know about the other. For example, the wave nature and particle nature of the electron are complementary.
Conrotatory
A term used to indicate that p orbitals must rotate in the same direction during electrocyclic ringopening or ring-closure.
coordinate covalent bond
The bond formed when a ligand donates electrons to an empty orbital of a metal in a complex ion.
core electrons
Those electrons in a complete principal energy level and those in complete d and f sublevels.
cyclic electron flow
In chloroplasts, the light-induced flow of electrons originating from and returning to photosystem I.
cytochrome c
Soluble component of the mitochondrial electron-transport chain. Its release into the cytosol from the mitochondrial intermembrane space also initiates apoptosis.
cytochrome c reductase
Second of the three electrondriven proton pumps in the respiratory chain. Accepts electrons from ubiquinone and passes them to cytochrome c.
Deactivating groups
Electron-withdrawing substituents that decrease the reactivity of an aromatic ring toward electrophilic aromatic substitution.
degenerate
A term describing two or more electron orbitals with the same value of n that have the same energy.
Deshielding
An effect observed in NMR that causes a nucleus to absorb toward the left (downield) side of the chart. Deshielding is caused by a withdrawal of electron density from the nucleus.
diode
A device that allows the flow of electrical current in only one direction.
Disrotatory
A term used to indicate that p orbitals rotate in opposite directions during electro cyclic ring-opening or ring-closing reactions.
duet
A Lewis symbol with two dots, signifying a filled outer electron shell for the elements H and He.
effective nuclear charge (Zeff)
The actual nuclear charge experienced by an electron, defined as the charge of the nucleus plus the charge of the shielding electrons.
electrical charge
A fundamental property of certain particles that causes them to experience a force in the presence of electric fields.
electrical conductance
The relative ability of an electrical charge to migrate from one point to another, represented by the symbol g and measured in siemens (S). Conductance is the inverse of resistance and is related to electrical current and voltage by Ohm’s law.
electrical potential
The force exerted on an electrically charged particle, represented by the symbol V and measured in volts; also called voltage or potential difference.
electrical resistance
The relative inability of an electrical charge to migrate from one point to another, represented by the symbol R and measured in ohms (Ω). Resistance is the inverse of conductance and is related to electrical current and voltage by Ohm’s law.
electrical self-stimulation
Electrical stimulation that an animal can voluntarily deliver to a portion of its brain.
electroconvulsive therapy (ECT)
A treatment for major depression that involves eliciting electrical seizure activity in the brain.
Electrocyclic reaction
A unimolecular pericyclic reaction in which a ring is formed or broken by a concerted reorganization of electrons through a cyclic tran sition state. For example, the cyclization of 1,3,5-hexatriene to yield 1,3-cyclohexadiene is an electrocyclic reaction.
electrode
A conductive surface through which electrons can enter or leave a half-cell in an electrochemical cell.
electrolysis
The process in which electrical current drives an otherwise nonspontaneous redox reaction.
electrolyte balance
Maintenance of the appropriate levels of electrolytes (such as sodium ions) in body fluids.
electrolytic cell
An electrochemical cell that consumes electrical current to drive a nonspontaneous chemical reaction.
electromagnetic radiation
A form of energy embodied in oscillating electric and magnetic fields.
electromotive force (emf)
The force that results in the motion of electrons due to a difference in potential.
electron capture
The form of radioactive decay that occurs when a nucleus assimilates an electron from an inner orbital.
electron microscope (EM) tomography
Technique for viewing three-dimensional specimens in the electron microscope in which multiple views are taken from different directions by tilting the specimen holder. The views are combined computationally to give a three-dimensional image.
electron transfer
Movement of electrons from electron donor to electron acceptor; especially, from substrates to oxygen via the carriers of the respiratory (electron-transfer) chain.
Electrophilic aromatic substitution reaction
A reaction in which an electrophile (E1) reacts with an aromatic ring and substitutes for one of the ring hydrogens.