Chapter 4 Flashcards
Activation Energy (Ea)
The initial amount of energy that must be invested to start a chemical reaction. Enzymes lower this barrier
Active Site
A specific region on an enzyme, usually a pocket or groove, that binds the substrate and where catalysis occurs
Anabolic Pathway
A metabolic pathway that consumes energy to build complex molecules from simpler ones; also known as biosynthetic pathway
ATP (adenosine Triphosphate)
The primary energy-carrying molecule in cells, composed of adenosine (adenine=ribose) and three phosphate groups
Catabolic pathway
A metabolic pathway that release energy by breaking down complex molecules into simple compounds
Cofactor
A non-protein helper molecule or ion that is required for the proper functioning of an enzyme. Can be inorganic (EX: metal ions)
Coenzyme
An organic molecule that acts as a cofactor often derived from vitamins
Competitive inhibitor
A substance that reduces enzyme activity by binding to the enzymes active site in place of the substrate
Dehydrogenase
an enzyme that catalyzes redox reactions, specifically the removal of hydrogen atoms (which are often transferred along with electrons) from a substrate
Endergonic Reaction:
A non-spontaneous chemical reaction that absorbs free energy from its surrounding (deltaG > 0)
Energy coupling
The use of energy released from an exergonic process to drive and endergonic one
Entropy
A measure of disorder or randomness in a system. The second law of thermodynamics states that the entropy of the universe tends to increase
Enzyme
A catalytic protein that speeds up metabolic reactions without being consumed in the process by lowering the activation energy
Exergonic Reaction
A spontaneous chemical reaction that releases free energy to surroundings (deltaG < 0)
Irreversible inhibitor
A substance that permanently inactivates an enzyme, usually by forming a covalent bond with it
Metabolic pathway
series of enzymatic reactions that transform starting material into a specific product
Metabolism
The totality of an organisms chemical reactions, consisting of catabolic and anabolic pathways
Non-Competitive inhibitor
A substance that reduces enzyme activity by binding to a site on the enzyme separate from the active site, causing a conformational change that reduces the enzymes effectiveness
Oxidation
The loss of an electron from a substance in a redox rection
Phosphorylation
The addition of a phosphate group to a molecule, often from ATP, making the molecule more reactive
Product
The molecules that result from a chemical reaction
redox reaction
A chemical reaction involving both oxidation (loss of electrons) and reduction (gain of electrons)
Reduction
The gain of electrons by a substance in a redox rection
Reversible inhibitor
A substance that inhibits enzyme activity by binding non-covalently to the enzyme; the inhibition is temporary and can be reversed
Spontaneous Reaction
A reaction that occurs without the input of external energy, driven by a decrease in free energy (DeltaG < 0)
Substrate
The reactant on which an enzyme acts
Thermodynamics
The study of energy transformation that occur in a collection of matter
Electron shuttle molecule
molecule (EX: NAD+, FAD) that cab accept high-energy electrons from ne molecule and donate them to another metabolic pathways
Electron Transport chain
A series of protein complexes in the inner membrane of mitochondria (or plasm membrane of prokaryotes) that carries out a sequence of redox reactions, ultimately generating ATP
