7.4 Respiration versus Lithotrophy

respiration

the overall process of catabolism from substrate breakdown to reduction of a terminal electron acceptor (such as O₂); uses an ETS

lithotrophy

transfers electrons from an inorganic molecule, such as iron or ammonia

aerobic respiration

the use of oxygen as the final acceptor of an electron transport system

oxidative phosphorylation

the use of PMF to drive ATP synthase to form ATP from ADP

38 molecules

during glucose respiration, how many ATP molecules can be made per molecule of glucose

oxidoreductase

an electron transport system enzyme that receives electrons from a stronger electron donor and then transfers those electrons to a stronger electron acceptor

quinones and quinols

small aromatic molecules that are soluble in the membrane

quinols

diffuse laterally within the membrane but do not cross the membrane between cytoplasm and exterior

8 H⁺

how many H⁺ ions may be pumped across the membrane for each NADH molecule that is oxidized

electron transport system (ETS)

transfers electrons from one membrane-embedded oxidoreductase to the next, the final one transfers to the terminal electron acceptor; generates a gradient of hydrogen ions across the membrane, that is, a larger concentration of H⁺ outside than inside

proton motor force (PMS)

the potential energy of the concentration gradient of protons (H⁺) plus the charge difference across a membrane; drives ATP synthase to phosphorylate ADP into ATP

bacteria

sacrifice efficiency for flexibility by spending some PMF energy to maintain stable ion gradients during environmental changes; have cellular processes that use the PMF directly, like flagellar rotation, and the PMF spent of processes cannot be used to power ATP synthase

anaerobic respiration

the use of a molecule other than oxygen as the final electron acceptor of an ETS

lithotrophy

metabolic oxidation of inorganic compounds to yield the energy used to reduce CO₂; uses an ETS

methanogenesis

an anaerobic reaction of CO₂ and H₂ to form methane (CH₄)