Cellular Respiration

cellular respiration

Metabolic reactions that use the energy from carbohydrate, fatty acid, or amino acid breakdown to produce ATP molecules.

NAD+ (nicotinamide adenine dinucleotide)

Coenzyme in oxidation-reduction reactions that accepts electrons and hydrogen ions to become NADH + H⁺ as oxidation of substrates occurs. During cellular respiration, NADH carries electrons to the electron transport chain in mitochondria.

FAD

Flavin adenine dinucleotide; a coenzyme of oxidation-reduction that becomes FADH₂ as oxidation of substrates occurs in the mitochondria during cellular respiration; FAD then delivers electrons to the electron transport chain.

aerobic

Chemical process that requires air (oxygen); phase of cellular respiration that requires oxygen.

anaerobic

Chemical reaction that occurs in the absence of oxygen; an example is the fermentation reactions.

fermentation

Anaerobic breakdown of glucose that results in a gain of two ATP and end products, such as alcohol and lactate; occurs in the cytoplasm of cells.

glycolysis

Anaerobic breakdown of glucose that results in a gain of two ATP and the production of pyruvate; occurs in the cytoplasm of cells.

substrate-level ATP synthesis

Process in which ATP is formed by transferring a phosphate from a metabolic substrate to ADP

mitochondrion

Membrane-bound organelles in which ATP molecules are produced during the process of cellular respiration.

preparatory (prep) reaction

Reaction that oxidizes pyruvate with the release of carbon dioxide; results in acetyl CoA and connects glycolysis to the citric acid cycle.

citric acid cycle

Cycle of reactions in mitochondria that begins with citric acid. This cycle breaks down an acetyl group and produces CO₂, ATP, NADH, and FADH₂; also called the Krebs cycle.

electron transport chain (ETC)

Process in a cell that involves the passage of electrons along a series of membrane-bound electron carrier molecules from a higher to lower energy level; the energy released is used for the synthesis of ATP.

cytochromes

Any of several iron-containing protein molecules that are members of the electron transport chain in photosynthesis and cellular respiration

chemiosmosis

Process by which mitochondria and chloroplasts use the energy of an electron transport chain to create a hydrogen ion gradient that drives ATP formation

catabolism

Metabolic process that breaks down large molecules into smaller ones; catabolic metabolism

anabolism

Chemical reaction in which smaller molecules (monomers) are combined to form larger molecules (polymers); anabolic metabolism

metabolic pool

Metabolites that are the products of and/or the substrates for key reactions in cells, allowing one type of molecule to be changed into another type, such as carbohydrates converted to fats

deamination

Removal of an amino group (—NH₂) from an amino acid or other organic compound