...: the metabolic process by which an organism obtains energy by reacting oxygen with glucose to give water, CO2 and ATP (energy).
...The transfer of electrons during chemical reactions releases energy stored in organic molecules.
... that transfer electrons between reactants are called oxidationreduction reactions, or redox reactions
...a substance loses electrons, or is oxidized
... a substance gains electrons, or is reduced (the amount of positive charge is reduced).
During cellular respiration, the fuel (such as glucose) is oxidized, and O2 is reduced.
the fuel (such as glucose) is oxidized, and O2 is reduced.
Glucose. Energy is released when electrons fall down an
... acts as electron donor
...is released when electrons fall down an energy gradient.
... from organic compounds are usually first transferred to NAD+, a coenzyme.
As an electron acceptor
...NAD+ functions as an oxidizing agent during cellular respiration.
Cellular respiration has three stages:
...Glycolysis (breaks down glucose into two molecules of pyruvate)
The citric acid cycle (completes the breakdown of glucose)
Oxidative phosphorylation (accounts for most of the ATP synthesis)
...and the citric acid cycle supply electrons (via NADH or FADH2) to the electron transport chain, which drives oxidative phosphorylation.
a ______ amount of ATP is formed in glycolysis and the citric acid cycle.
...("splitting of sugar") breaks down glucose into two molecules of pyruvate.
...occurs in the cytoplasm (outside of mitochondria)
... is released during glycolysis. Glycolysis occurs whether or not O2 is present.
Citric acid cycle
...In the presence of O2, pyruvate enters the mitochondrion.
Before the citric acid cycle can begin
pyruvate must be converted to acetyl CoA, which links the cycle to glycolysis.
The citric acid cycle
takes place within the mitochondrial matrix.
...is broken down to three CO2
The cycle oxidizes organic fuel derived from pyruvate, generating ATP (substrate-level
... generating ATP (substrate-level phosphorylation), NADH and FADH2 which relay electrons extracted from food to the electron transport chain.
Following glycolysis and the citric acid cycle, NADH and FADH2 account for most of NADH and FADH2 account for most of the energy extracted from food.
Following glycolysis and the citric acid cycle, NADH and FADH2 account for most of
...NADH and FADH2 account for most of the energy extracted from food.
Electron transport chain
These two electron carriers donate electrons to the electron transport chain, which powers ATP synthesis via oxidative phosphorylation.
... drop in free energy as they go down the electron transport chain and are finally passed to O2, forming H2O.
...is to break the large free-energy drop from food to O2 into smaller steps that release energy in manageable amounts
Electron transfer in the electron transport chain causes proteins to pump H+ from the mitochondrial matrix to the intermembrane space
H+ then moves back across the membrane, passing ATP synthase uses the exergonic flow of H+ to drive phosphorylation of ATPthrough channels in ATP synthase
This is an example of ___, the use of energy in a H+ gradient to drive cellular work
During cellular respiratio, most energy flows in this sequence
Glucose → NADH → electron transport chain → proton-motive force → ATP
Fermentation and anaerobic respiration
...Most cellular respiration requires O2 to produce ATP
Glycolysis can produce ATP with or without O2 (in aerobic or anaerobic conditions)
In the absence of O2, glycolysis couples with fermentation or anaerobic respiration to produce ATP
Versatility of Catabolism
Glycolysis and the citric acid cycle connect to many other metabolic pathways
Regulation of cellular respiration via Feedback mechanisms