3. Cell Metabolism Flashcards
The energy required to raise a molecule to its transition state to undergo a chemical reaction.
activation energy
The region of an enzyme that binds substrates and catalyzes an enzymatic reaction.
active site
ATP
adenosine 5′-triphosphate (ATP)
The regulation of enzymes by small molecules that bind to a site distinct from the active site, changing the conformation and catalytic activity of the enzyme.
allosteric regulation
A series of reactions by which six molecules of CO2 are converted into glucose.
Calvin cycle
The major photosynthetic pigment of plant cells.
chlorophyll
A series of reactions in which acetyl CoA is oxidized to CO2. The central pathway of oxidative metabolism.
citric acid cycle
Low-molecular-weight organic molecules that work together with enzymes to catalyze biological reactions.
coenzyme
A coenzyme that functions as a carrier of acyl groups in metabolic reactions.
coenzyme A (CoA-SH)
The series of reactions that convert carbon dioxide and water to carbohydrates during photosynthesis. See Calvin cycle.
dark reactions
A series of carriers through which electrons are transported from a higher to a lower energy state.
electron transport chain
A protein or RNA that catalyzes a biological reaction.
enzyme
A type of allosteric regulation in which the product of a metabolic pathway inhibits the activity of an enzyme involved in its synthesis.
feedback inhibition
A coenzyme that functions as an electron carrier in oxidation/reduction reactions.
flavin adenine dinucleotide (FADH2)
The thermodynamic function that combines the effects of enthalpy and entropy to predict the energetically favorable direction of a chemical reaction.
Gibbs free energy (G)
The synthesis of glucose.
gluconeogenesis
The anaerobic breakdown of glucose.
glycolysis
A chemical bond that releases a large amount of free energy when it is hydrolyzed.
high-energy bond
A model of enzyme action in which the configurations of both the enzyme and the substrate are altered by substrate binding.
induced fit
A series of reactions in which acetyl CoA is oxidized to CO2. The central pathway of oxidative metabolism.
Krebs cycle
The reactions of photosynthesis in which solar energy drives the synthesis of ATP and NADPH.
light reactions
A model of enzyme action in which the substrate fits precisely into the enzyme active site.
lock-and-key model
A coenzyme that functions as an electron carrier in oxidation/reduction reactions.
nicotinamide adenine dinucleotide (NAD+)
The reduction of atmospheric nitrogen (N2) to NH3.
nitrogen fixation
The synthesis of ATP from ADP, coupled to the energetically favorable transfer of electrons to molecular oxygen as the final acceptor in an electron transport chain.
oxidative phosphorylation
The addition of a phosphate group to a molecule.
phosphorylation
A molecule that captures energy from sunlight by absorbing photons.
photosynthetic pigment
A compound formed as a result of an enzymatic reaction.
product
A small molecule bound to a protein.
prosthetic group
A molecule acted upon by an enzyme.
substrate
A high energy state through which substrates must pass during the course of an enzymatic reaction.
transition state
