C.1.2 Cell respiration

Based on the 3rd edition biology textbook written by C.J. Clegg, Andrew Davis, Christopher Talbot

cell respiration

the enzyme-controlled release of energy from organic compounds to produce ATP

adenosine triphosphate (ATP)

a nucleotide, present in every living cell, formed in photosynthesis and respiration from ADP + P, and functioning in metabolism as a common intermediate between energy-requiring and energy-yielding reactions

adenosine diphosphate (ADP)

a nucleotide present in every living cell, made of adenosine and two phosphate groups bonded in a linear sequence; it is important in energy-transfer reactions of metabolism

aerobic respiration

respiration requiring oxygen, involving the oxidation of glucose to carbon dioxide and water

anaerobic respiration

respiration in the absence of oxygen, producing either lactic acid (humans) or ethanol and carbon dioxide (plants and yeast)

lactic acid

organic acid produced by the body when glucose is broken down to generate ATP in the absence of oxygen; lactic acid is formed by lactate in solution

reduction

the gain of electrons in a chemical reaction; this can be by removing oxygen atom or by adding hydrogen atoms; is endergonic

oxidation

the loss of electrons in a chemical reaction; this can be by adding oxygen atoms or by removing hydrogen atoms; is exergonic

redox reaction

linked reaction where one substance loses an electron while the other gains an electron

coenzyme

substance that works with an enzyme to initiate or aid the function of the enzyme

NAD+ (NADH or NADH2) and FAD+ (FADH2)

a coenzyme that is a hydrogeen carrier in cellular respiration; it is reduced with additional hydrogen atoms

pyruvate

the end product of glycolysis, which is converted into acetyl-CoA that enters the Krebs cycle when there is sufficient oxygen available

glycolysis

the first stage of cell respiration in which glucose is converted to pyruvate by stepwise enzyme-controlled reactions, without the use of oxygen; a net gain of 2 ATP molecules

phosphorylation

the addition of a phosphoryl group to an organic compound

decarboxylation

a chemical reaction that releases carbon dioxide (usually with hydrogen replacing it)

link reaction

the reactions that connect glycolysis to the reactions of the Krebs cycle by producing acetyl coenzyme A from pyruvate; carbon dioxide and NADH are produced by this reaction

Krebs cycle

the cyclical metabolic process in aerobic cell respiration involving the oxidation and decarboxylation of acetyl groups, with a yield of ATP and reduced NAD

electron transport chain

a series of proteins that transfer electrons received from reduced coenzymes, generating a gradient of protons that drives the synthesis of ATP

chemiosmosis

process by which the synthesis of ATP is coupled to electron transport via the movement of protons, using ATP synthase

ATP synthase (ATPase)

a complex of integral proteins located in the mitochondrial inner membrane where it catalyses the synthesis of ATP from ADP and phosphate, driven by a flow of protons