24 terms

AP Biology Chapter 9 Vocabulary

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Fermentation
a catabolic process that is a partial degradation of sugars that occurs without the use of oxygen
Cellular respiration
the most prevalent and efficient catabolic pathway in which oxygen is consumed as a reactant along with the organic fuel -in a eukaryotic cell, mitochondria contain most of the metabolic equipment necessary for this
Redox reactions
a chemical reaction where there is a transfer of one or more electrons from one reactant to another -also called oxidation-reduction reactions
Oxidation
occurs in a redox reaction, and is the loss of electrons from one substance
Reduction
the addition of electrons to another substance
Reducing agent
the electron donor that reduces the other substance (which in turn accepts the donated electron)
Oxidizing agent
the electron acceptor that oxidizes the other substance by removing its electron
NAD+
a coenzyme (nicotinamide adenine dinucleotide) that functions as the oxidizing agent during respiration -traps electrons from glucose and other organic molecules
Electron transport chain
used during respiration to break the fall of electrons to oxygen into several energy-releasing steps instead of one explosive reaction -consists of a number of molecules (mostly proteins) built into the inner membrane of a mitochondrion
Glycolysis
one of the first two stages of cellular respiration -is a catabolic pathway that decomposes glucose and other organic fuels -occurs in cytosol and begins the degradation process by breaking glucose into two molecules of a compound called pyruvate
Citric acid cycle
takes place within the mitochondrial matrix and completes the breakdown of glucose by oxidizing a derivative of pyruvate to carbon dioxide
Oxidative phosphorylation
a mode of ATP synthesis that is powered by the redox reactions of the electron transport chain -energy released at each step of the chain is stored in a form the mitochondrion can use to make ATP
Substrate-level phosphorylation
a method of ATP synthesis when a smaller amount of ATP is formed directly in a few reactions of glycolysis and the citric acid cycle by this mechanism -occurs when an enzyme transfers a phosphate group from a substrate molecule to ADP, rather than adding an inorganic phosphate to ADP as in oxidative phosphorylation
Acetyl CoA
a compound that pyruvate is first converted to upon entering the mitochondrion via active transport -this step is the junction between glycolysis and the citric acid cycle, & is accomplished by a multi-enzyme complex that catalyzes three reactions
Cytochromes
proteins that are electron carriers between ubiquinone and oxygen -belong to a prosthetic group called the heme group -has an iron atom that accepts and donates electrons -electron transport chain has several types of this, each a different protein
Chemiosmosis
a process in which energy is stored in the form of a hydrogen ion gradient across a membrane is used to drive cellular work such as synthesis of ATP -refers to the flow of H+ ions across a membrane
ATP synthase
a protein complex that is the enzyme that actually makes ATP from ADP and inorganic phosphate -works like an ion pump running in reverse -uses the energy of an existing ion gradient to power ATP synthesis
Proton-motive force
the H+ gradient that results from the electron carriers being spatially arranged in the membrane in such a way that H+ is accepted from the mitochondrial matrix and deposited in the intermembrane space -emphasizes the capacity of the gradient to perform work
Aerobic
a condition where oxygen is present
Anaerobic
a condition where oxygen is NOT present
Alcohol fermentation
when pyruvate is converted to ethanol (ethyl alcohol) in two steps -the first releases carbon dioxide from the pyruvate, which is then converted to the 2-carbon compound acetaldehyde -in the second step, acetaldehyde is reduced by NADH to ethanol -this generates the supply of NAD+ needed for the continuation of glycolysis
Lactic acid fermentation
when pyruvate is reduced directly by NADH to form lactate as an end product, with no release of CO2 -human muscle cells make ATP by this when oxygen is scarce
Facultative anaerobes
species (such as yeast and many bacteria) that can make enough ATP to survive using either fermentation or respiration -our muscle cells behave as this
Beta oxidation
a metabolic sequence that breaks the fatty acids down to two-carbon fragments, which enter the citric acid cycle as acetyl CoA -fats make excellent fuel
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