Cellular Respiration

Cellular Respiration

metabolic process in living organisms by which oxygen is combined with carbon in a cell to form carbon dioxide and generate high energy ATP. Occurs in the mitochondria. 

Aerobes

organisms that are dependent upon and use oxygen to sustain their lives.

Anaerobes

organisms that are not dependent upon and which do not use oxygen in their lives.

Fermentation

the incomplete breakdown of glucose; occurs primarily in the absence of oxygen.

Glycolysis

the process by which both fermentation and aerobic respiration begin to break apart glucose; the universal first step in extracting energy from glucose.

Substrate-Level Phosphorylation

a way cells make ATP by directly adding a phosphate to ADP from another molecule. It doesn’t need oxygen and happens during glycolysis, fermentation, and the Krebs cycle.

Acetyl Fragment

he 2-carbon fragment formed when pyruvic acid splits into one carbon and a 2-carbon piece during the early steps of the Krebs cycle.

Coenzyme A

the coenzyme that acts as a carrier molecule for the acetyl fragment; it initially couples with the acetyl fragment and transports it to oxaloacetic acid.

Electron transport system

a system in which electrons travel in a chain from one electron acceptor molecule to the next; energy is released with each transfer and can be used to form ATP.

Oxidative Phosphorylation

how cells make energy (ATP) by using oxygen, ADP, and phosphate in a chain of reactions. It’s more efficient than other methods, but it only works when oxygen is available.

Cytochrome oxidase

Final electron acceptor/carrier molecule in the electron transport system of aerobic respiration; it is a huge complex of proteins.

ATP Synthase

the enzyme used in the reactions that ultimately form ATP.

Metabolic Pool

all substances and processes that either release energy (ATP) by breaking things down or use energy (ATP) to build larger molecules.

Catabolism

metabolic pathways that degrade complex compounds into simpler molecules; release energy (=energy-releasing pathways).

Anabolism

metabolic pathways that result in the biosynthesis of complex molecules from simpler components; require energy (=energy-acquiring pathways).