After pyruvate is oxidized, the citric acid
cycle completes the energy-yielding
oxidation of organic molecules
Glycolysis releases less than a quarter of the chemical energy
in glucose that can be harvested by cells; most of the energy
remains stockpiled in the two molecules of pyruvate. When
O2 is present, the pyruvate in eukaryotic cells enters a mitochondrion,
where the oxidation of glucose is completed.
Upon entering the mitochondrion via active transport, pyruvate
is first converted to a compound called acetyl coenzyme
A, or acetyl CoA. This step, linking glycolysis
and the citric acid cycle,
The citric acid cycle functions as a metabolic furnace that
oxidizes organic fuel derived from pyruvate. Pyruvate is broken
down to three CO2 molecules, including the molecule of
CO2 released during the conversion of pyruvate to acetyl
CoA. The cycle generates 1 ATP per turn by substrate-level
phosphorylation, but most of the chemical energy is transferred
to NAD+ and a related electron carrier, the coenzyme
FAD (flavin adenine dinucleotide, derived from riboflavin,
a B vitamin), during the redox reactions. The reduced coenzymes,
NADH and FADH2, shuttle their cargo of highenergy
electrons into the electron transport chain. The citric
acid cycle is also called the tricarboxylic acid cycle or the
Krebs cycle, the latter honoring Hans Krebs, the German-
British scientist who was largely responsible for working out
the pathway in the 1930s.
#KrebsCycleSteps
source
Krebs Cycle – Citric acid Cycle or TCA | Cellular respiration | Biology lecture
