Brock's Microbes Chapter 3

ABC (ATP-binding cassette) transport system

a membrane transport system consisting of three proteins, one of which hydrolyzes ATP; the system transports specific nutrients into the cell

Activation energy

the energy required to bring the substrate of an enzyme to the reactive state

Adenosine triphosphate (ATP)

a nucleotide that is the primary form in which chemical energy is conserved and utilized in cells Anabolic reactions (Anabolism) the sum total of all biosynthetic reactions in the cell

Anabolic reactions (Anabolism)

the sum total of all biosynthetic reactions in the cell

Anaerobic respiration

a form of respiration in which oxygen is absent and alternative electron acceptors are reduced

ATPase (ATP synthase)

a multiprotein enzyme complex embedded in the cytoplasmic membrane that catalyzes the synthesis of ATP coupled to dissipation of the proton motive force

Autotroph

an organism capable of biosynthesizing all cell material from CO2 as the sole carbon source

Calvin cycle

the series of biosynthetic reactions by which most phototrophs and many chemolithotrophs convert CO2 into organic compounds

Catabolic reactions (catabolism)

biochemical reactions leading to energy conservation (usually as ATP) by the cell

Chemolithotroph

an organism that can grow with inorganic compounds as electron donors in energy metabolism compounds

Chemoorganotroph

an organism that obtains its energy from the oxidation of organic

Citric acid cycle

a cyclical series of reactions resulting in the conversion of acetate to two molecules of CO2

Coenzyme

a small and loosely bound nonprotein molecule that participates in a reaction as part of an enzyme

Electron acceptor

a substance that can accept electrons from an electron donor, becoming reduced in the process

Electron donor

a substance that can donate electrons to an electron acceptor, becoming oxidized in the process

Endergonic

a reaction that requires free energy

Enzyme

a protein that can speed up (catalyze) a specific chemical reaction (a few RNAs are also enzymes)

Exergonic

a reaction that releases free energy

Fermentation

anaerobic catabolism in which an organic compound is both an electron donor and an electron acceptor and ATP is produced by substrate-level phosphorylation

Free energy (G)

energy available to do work; G09 is free energy under standard conditions

Glycolysis

a biochemical pathway in which glucose is oxidized to pyruvate, which is either used in respiration or fermented; yields ATP and, in fermentation, various fermentation products (also called the Embden-Meyerhof-Parnas pathway)

Glyoxylate

cycle a modification of the citric acid cycle in which isocitrate is cleaved to form succinate and glyoxylate during growth on two-carbon electron donors such as acetate

Group translocation

an energy-dependent transport system in which the substance transported is chemically modified during the process of being transported by a series of proteins

Heterotroph

an organism that uses organic compounds as a carbon source

Oxidative

phosphorylation the production of ATP from a proton motive force formed by electron transport of electrons from organic or inorganic electron donors

Pentose phosphate pathway

a series of reactions in which pentoses are catabolized to generate precursors for nucleotide biosynthesis or to synthesize glucose

Photophosphorylation

the production of ATP from a proton motive force formed from light-driven electron transport

Phototrophs

organisms that use light as their source of energy

Proton motive force (pmf)

a source of energy resulting from the separation of protons from hydroxyl ions across the cytoplasmic membrane, generating a membrane electrochemical potential

Reduction potential (E09)

the inherent tendency, measured in volts under standard conditions, of a compound to donate or to accept electrons

Respiration

the process in which a compound is oxidized with O2 (or an O2 substitute) as the terminal electron acceptor, usually accompanied by ATP production by oxidative phosphorylation

Simple transport system

a transporter that consists of only a membranespanning protein and is typically driven by energy from the proton motive force

Substrate-level phosphorylation

the production of ATP by the direct transfer of an energy-rich phosphate molecule from a phosphorylated organic compound to ADP