Unit 1 Ch 3 - Microbial Metabolism Flashcards
from Unit 1 -The Foundations of Microbiology
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
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 ATP) by the cell
Chemolithotroph
an organism that can grow with inorganic compounds as electron donors in energy metabolism
Chemoorganotroph
an organism that obtains its energy from the oxidation of organic compounds
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 and electron donor and an electron acceptor and ATP is produced by substrate-level phosphorylation
Free energy (G)
energy available to do work; G0 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 (aka 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 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 and 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 (E0’)
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 membrane-spanning 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
