The compound that enters the citric acid cycle. Pyruvate is converted to acetyl coenzyme A in the transition step before the citric acid cycle. It is often shortened to acetyl-CoA. Try saying it five times fast.
Aerobic Respiration
Energy metabolism in the presence of oxygen. No leg warmers here.
Alcohol Fermentation
The process of converting glucose to usable energy in the absence of oxygen, producing alcohol and carbon dioxide along the way. Bacteria and fungi undergo alcohol fermentation, so don't try this at home, folks. Actually, you can try it at home…by letting bread dough rise.
Anaerobic Pathway
The metabolic processes that happen without oxygen.
Adenosine Triphosphate
The end-all, be-all to a cell. Short for adenosine triphosphate, ATP is energy to a cell, and without energy, life is a no go. ATP is the main attraction in cellular respiration.
ATP Synthase
The really awesome motor-like enzyme that makes ATP. If you forgot what an enzyme is, check it out.
Cellular Respiration
The thrilling, breath-taking process that brought you to this module. Cellular respiration is a way of extracting energy from food and making it useful to the cell. Cellular respiration involves a lot of oxidation and reduction reactions. Nuff said.
Chemical Energy
The energy released in a chemical reaction.
Citric Acid Cycle
The process that oxidizes acetyl coenzyme-A to energy-producing compounds.
Electron Transport Chain
The step-by-step process of removing electrons from NADH and FADH2 to power ATP synthesis.
Endosymbiosis
The engulfing of one small organism by a larger one that results in a mutually beneficial relationship. Mitochondria and chloroplasts evolved through embosymbiosis.
Energy Coupling
The pairing of an energy-releasing reaction with an energy-consuming reaction.
FAD
A trendy activity or article of clothing. Oh sorry, wrong glossary. FAD is also a compound that accepts electrons and is important to the citric acid cycle.
Fermentation
The process of oxidizing glucose without oxygen.
Glycolysis
The first step in getting energy out of food. Glycolysis breaks one glucose molecule down into two molecules of pyruvate. Glycolysis happens in almost all organisms, and it can take place with or without oxygen. Here at Shmoop, we are pretty sure the U2 song "With or Without You" was really about glycolysis and oxygen.
Krebs Cycle
A synonym for the citric acid cycle. Why do biologists give one process multiple names? We'll never know. The name Krebs cycle pays homage to the man who discovered it, Hans Krebs.
Lactic Acid Fermentation
One of the two types of fermentation. It converts glucose to ATP when oxygen is not present, and produces lactic acid in the process. We have lactic acid fermentation to thank for cheese and yogurt. (Thank you × 3, lactic acid fermentation!)
Metabolism
The name for the chemical reactions and processes that extract energy from food so that an organism can use it.
Mitochondrial Matrix
The inner chamber of a mitochondrion. The matrix is where the mitochondrion keeps all its dirty little secrets.
Nicotinamide Adenine Dinucleotide Ion (NAD+)
An electron carrier used in the citric acid cycle, but it makes an appearance in the electron transport chain, too.
NADPH
The reduced form of NAD+, found in the citric acid cycle. It donates electrons to the electron transport chain. NADH is an "energy equivalent" in that it does not directly produce energy like ATP does; it causes ATP to be produced.
Oxaloacetate
The first compound of any real importance in the citric acid cycle. Yay! The input, acetyl-CoA, joins with oxaloacetate for a spin around the citric acid cycle, which has four carbons and just happens to be the first and last compound of the cycle.
Oxidation
A reaction that causes the loss of an electron. Oxidation never leaves the house without reduction, though, so we always know where that electron went.
Phosphorylation
The addition of an inorganic phosphate to something. Often, adenosine diphosphate (ADP) is phosphorylated to become ATP.
Pyruvate
The compound that glucose is oxidized to during glycolysis. One glucose molecule is converted into two pyruvate molecules.
Reduction
A reaction that causes the gain of an electron. Like oxidation reactions, reduction reactions do not exist alone, so if one thing is being reduced, then something else is being oxidized…it just doesn't know it yet.
Synthase
An enzyme (-ase) that links two molecules, like the frosting in an Oreo cookie.