An Introduction to Metabolism/Cellular Respiration Flashcards
Metabolism
The sum of all chemical reactions in a cell or organism
Activation Energy (Ea)
The minimum amount of energy that chemical reactants must absorb to start a reaction
Exergonic reaction
A chemical reaction that releases free energy; the products have less free energy than the reactants
Ex. the burning of wood
Endergonic reaction
A chemical reaction that absorbs free energy; the products have more free energy than the reactants
Ex. conversion of carbon dioxide and water into glucose and oxygen gas
Catabolic pathway
A pathway in which energy is released and complex molecules are broken down into simple molecules
Ex. cellular respiration in which energy is extracted from the breakdown of food such as glucose
Anabolic pathway
A pathway in which energy is supplied to build complex molecules from simple molecules
Ex. photosynthesis, the synthesis of macromolecules such as proteins or nucleic acids
Phosphorylation
The transfer of a phosphate group, usually from ATP, to another molecule
ATP cycle
The cyclic and ongoing breakdown and re-synthesis of ATP
Dehydrogenase
An enzyme that oxidizes a substrate and transfers hydrogen ions to an acceptor
NADH
The reduced form of the coenzyme nicotinamide adenine dinucleotide (NAD+)
Aerobic cellular respiration
A process that uses oxygen to harvest energy from organic compounds
Obligate aerobe
An organism that cannot live without oxygen
Ex. most eukaryotes, including all plants and animals
Substrate-level phosphorylation
The formation of ATP by the direct transfer of a phosphate group from a substrate to ADP
Oxidative phosphorylation
A process that forms ATP using energy transferred indirectly from a series of redox reaction
Glycolysis
A series of reactions in which a glucose molecule is broken into two pyruvate molecules and energy is released
Pyruvate oxidation
A reaction in which pyruvate is oxidized by NAD+, and carbon dioxide is removed, forming an acetyl group and releasing NADH
Citric acid cycle
A cyclic series of reactions that transfers energy from organic molecules to ATP, NADH, and FADH2, and releases carbon atoms as carbon dioxide
Anaerobic respiration
A process that uses a final inorganic oxidizing agent other than oxygen to produce energy
Fermentation
A process that uses an organic compound as the final oxidizing agent to produce energy
Obligate anaerobe
An organism that cannot survive in the presence of oxygen
Ex. protist Trichonympha or bacteria responsible for tetanus and botulism poisoning
Facultative anaerobe
An organism that can live with or without oxygen
Ex. yeast
Decarboxylation reaction
A chemical reaction that removes a carboxyl group to form carbon dioxide
Dehydrogenation
The removal of a hydrogen atom from a molecule
Proton gradient
A difference in proton (H+ ion) concentration across a membrane
Proton-motive force
A force that moves protons because of a chemical gradient (often referred to as an electrochemical gradient) of protons across a membrane
Chemiosmosis
A process in which ATP is synthesized using the energy of an electrochemical gradient and the ATP synthase enzyme
Alcohol fermentation
A process in which pyruvate is decarboxylated, producing a molecule each of carbon dioxide and of ethanol, and an NAD+
Ex. wine and beer
Lactate fermentation
A process in which pyruvate reacts with NADH and is converted directly into lactate and regenerates NAD+
Ex. making cheeses and flavour/preserve yogurt due to sour taste
Energy coupling
The transfer of energy from one reaction to another in order to drive the second reaction
