Chapter 9 Flashcards
metabolism
all the chemical reactions occurring in a living cell or organism
phosphorylation
the addition of a phosphate group to a molecule
energetic coupling
in cellular metabolism, the mechanism by which energy released from an exergonic reaction is used to drive an endergonic reaction
reduction-oxidation reactions
any chemical reaction that involves the transfer of one or more electrons from one reactant to another
electron donor
a reactant that loses an electron and is oxidizedduring a redox reaction
cytochrome c
a soluble iron-containing protein that shuttles electrons between membrane bound complexes in the mitochondrial electron transport chain
electron acceptor
a reactant that gains an electron and is reduced in a redox reaction
nicotinamide adenine dinucleotide
oxidized and reduced forms are NAD+ and NADH, a nonprotein electron carrier that is reduced during the light dependent reactions in photosynthesis and extensively used in biosynthetic reactions
electron carrier
any molecule that readily accepts electrons from and donates electrons to other molecules
substrate-level phosphorylation
production of ATP by transfer of a phosphate group from an intermediate substrate directly to ADP. Occurs in glycolysis and citric acid cycle
phosphofructokinase
the enzyme that catalyzes synthesis of fructose -1, 6-bisphosphate from from fructose 6-phosphate, a key step in glycolysis
feedback inhibition
a type of metabolic control in which high concentrations of the product of a metabolic pathway inhibit one of the enzymes early in the pathway
regulatory site
a site on an enzyme to which a regulatory molecule can bind and affect the enzymes activity, separate from the active site where catalysis occurs
coenzyme A
a nonprotein molecule that is required for many cellular reactions involving the transfer of acetyl groups
acetyl CoA
a molecule produced by the oxidation of a pyruvate catalyzed by pyruvate dehydrogenase, can enter the citric acid cycle and is also used as a carbon source in the synthesis of fatty acids, steroids and other compounds
lactic acid fermentation
catabolic pathway in which pyruvate produced by glycolysis is converted into lactic acid in the absence of oxygen
alcohol fermentation
catabolic pathway in which pyruvate produced by glycolysis is converted to ethanol in the absence of oxygen
carboxylic acids
organic acids with the form of R-COOH(carboxyl group)
citric acid cycle
a series of eight chemical reactions that starts with citrate and ends with oxaloacetate which reacts with acetyl CoA to form citrate- forming a cycle that is part of the pathway that oxidizes glucose into CO2
guanosine triphosphate
a molecule consisting of guanine, a sugar and three phosphate groups. can be hydrolyzed to release free energy and commonly used in many cellular reactions
ubiquinone
a nonprotein molecule that shuttles electrons between membrane bound complexes in the mitochondrial electron transport chain also called coenzyme Q
proton-motive force
the combined effect of a proton gradient and an electric potential gradient across a membrane, which can drive protons across the membrane. used by mitochondria and chloroplast to power ATP synthesis
chemiosmosis
an energetic coupling mechanism whereby energy stored in an electrochemical proton gradient is used to drive an energy requiring process such as the production of ATP
facultative anaerobes
any organism that can perform aerobic respiration when oxygen is available to serve as an electron acceptor but can switch to fermentation when there is not
catabolic pathways
any set of chemical reactions that breaks down larger. more complex molecules into smaller ones, releasing energy in the process
anabolic pathways
any set of chemical reactions that synthesize larger molecules from smaller ones, generally requires energy
