Cellular Respiration

Cellular Respiration

the process organisms use to breakdown glucose into water and carbon dioxide using an electron transport system to extract energy from electrons and store it as high-energy ATP; it is an energy-producing process that produces much net energy for the organism.

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.

Aerobic Respiration

the complete breakdown of glucose; requires the presence of oxygen to occur; the most common form of cellular respiration that uses Kreb’s Cycle (=Citric Acid Cycle) and an electron transport system; oxygen acts as the final electron acceptor molecule.

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

process in which ATP is formed by transferring a phosphate molecule from a metabolic substrate to ADP; H + drives the reaction, but oxygen is not used at all in this process; the ATP that is generated from glycolysis, fermentation, and Kreb’s Cycle is produced in this way.

Pyruvate (Pyruvic Acid)

the end-product of glycolysis; they will enter either fermentation or aerobic respiration next.

Acetyl Fragment

name for the 2-carbon fragment that results when the 3-carbon pyruvic acid molecule is initially split into one 1-carbon fragment and one 2-carbon fragment during the early stages of Kreb's 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

production of ATP through the use of ADP, inorganic phosphate, and an electron transport system in which oxygen is the final electron acceptor molecule; it is much more efficient than substrate-level phosphorylation, but oxygen is required for the process to occur; the ATP that is generated from the electron transport system is produced in this way.

Cytochrome oxidase

the last electron 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 that can be broken down to produce E (ATP) or used to build larger molecules by using ATP; represents a dynamic balance between catabolism and anabolism.

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).