Chapter 6: Metabolism Flashcards
assimilation
Process by which cells import a molecule and incorporate it into cellular constituents
phototroph
Organism that captures light energy, or photons, through the process of photosynthesis to generate chemical energy, such as ATP
lithotroph
Organism that removes electrons from inorganic reduced molecules, such as H2S, H2, or elemental sulfur (S0)
organic VS inorganic
Molecule containing carbon-hydrogen bonds vs one that does not
heterotroph
Organism that obtains carbon from organic molecules, such as sugars, obtained from the environment
autotroph
Organism that can build complex organic molecules used as nutrients from an inorganic carbon source
carbon fixation
Conversion of inorganic carbon, usually CO2, from the environment into organic molecules for growth; common in autotrophs
catabolism
Breakdown of larger molecules into smaller ones for energy production
anabolism
Biosynthesis of macromolecular cell components from smaller molecular units
cofactor
Small ion or organic molecule essential for enzyme catalytic activity by assisting in the transfer of functional groups
coenzyme
An organic cofactor
allosteric regulation
Regulation of enzyme action by an effector molecule that binds reversibly to the enzyme allosteric site and is not changed in the reaction; regulation can be positive (activation) or negative (inhibition)
tricarboxylic acid (TCA) cycle
Series of metabolic reactions used in the oxidation of carbon compounds, producing CO2, NADH, and ATP; also called the citric acid cycle or Krebs cycle
chemiosmosis
Synthesis of ATP from free ADP and Pi using energy and electrons to create a proton gradient across a membrane; the flow of protons back across the membrane releases energy that is harnessed by ATP synthase to produce ATP
photophosphorylation
Chemiosmotic process used by phototrophs to generate ATP using light energy; used by phototrophs
oxidative phosphorylation
Chemiosmotic process used by chemotrophs to generate ATP using the energy captured from oxidation of a chemical substrate; used by chemotrophs
nicotinamide adenine dinucleotide (NAD)
Cytoplasmic electron carrier molecule serving as a coenzyme
electron transport system
Chain of membrane-associated proteins that transfers electrons in a series of steps, yielding energy to move protons across the membrane
ATP synthase
Membrane enzyme complex that uses the kinetic energy of flowing protons to synthesize ATP from free ADP and Pi
redox reactions
Reduction and oxidation reactions involving the transfer of electrons from one molecule to another
Oxidized
Loss of Electrons (LEO the lion says GER)
Reduced
Gain of Electrons (LEO the lion says GER)
reduction potential
Tendency of a molecule to accept electrons; represented by the electrode potential, E, which is measured in units of volts (V); also called redox potential
Embden–Meyerhof–Parnas (EMP) pathway
Glycolytic pathway where glucose is converted into two molecules of pyruvate, producing a total of two molecules of ATP from each glucose molecule
anaplerotic reaction
Replenishing reaction that generates a critical metabolic intermediate in order to sustain another metabolic pathway
Entner–Doudoroff pathway (ED)
Glycolytic pathway interacting with the EMP pathway in which glucose is converted to two molecules of pyruvate, producing one molecule of ATP from each glucose molecule; commonly used for glucose catabolism but is often used for catabolism of other carbohydrates containing aldehyde groups, such as gluconate, which cannot be readily processed by the EMP pathway.
pentose phosphate pathway
Glycolytic pathway interacting with the EMP pathway where glucose is converted to a number of 3- to 7-carbon compounds, many of which are used for biosynthesis, and producing NADPH and ATP; The pathway is of significant importance since it generates NADPH for biosynthetic reactions. The pentose phosphate pathway works with the EMP pathway rather than replacing it. Its primary use is in generating the electron donor NADPH and essential precursors for biosynthesis.
fermentation
electrons are passed directly to an organic terminal electron acceptor and the TCA cycle and the electron transport system is not utilized
Cellular respiration
where the electrons are passed through an electron transport system and on to an inorganic or sometimes an organic terminal electron acceptor
primary difference between fermentation and respiration
fermentation does not use ETS and respiration does
