Anabolic and Catabolic Reactions & Metabolism - Vocabulary Flashcards

Vocabulary flashcards covering key terms from the lecture notes on anabolic and catabolic reactions, metabolism, enzymes, metabolic pathways, redox, glycolysis, respiration, fermentation, and lipid/protein catabolism.

Anabolism

Metabolic processes that build larger molecules from smaller ones; requires energy; also called synthesis.

Catabolism

Metabolic processes that break down larger molecules into simpler ones; energy-releasing; also called decomposition.

Dehydration synthesis

A condensation reaction that links two molecules with the removal of a water molecule to form a larger molecule.

Hydrolysis

A reaction that uses water to break bonds, splitting a molecule into smaller components.

Metabolism

All chemical reactions occurring in a living organism at a given time.

Metabolic pathway

A linked series of chemical reactions where the product of one step becomes the substrate for the next.

Enzyme

A protein that acts as a biological catalyst to speed up a specific biochemical reaction without being consumed.

Active site

The region of an enzyme where the substrate binds to catalyze a reaction.

Substrate

The reactant molecule that binds to an enzyme’s active site.

Enzyme inhibitor

A molecule that binds to an enzyme and decreases its activity.

Competitive inhibition

Inhibitor competes with the substrate for the enzyme’s active site; reversible and influenced by substrate/inhibitor concentrations.

Noncompetitive inhibition

Inhibitor binds to a site other than the active site, altering enzyme shape and reducing activity; not overcome by more substrate.

Allosteric site

Regulatory site on an enzyme where binding alters activity.

Feedback inhibition

End product inhibits an earlier enzyme in the pathway to regulate production.

Oxidation

Loss of electrons (or hydrogen) from a molecule; oxidation state increases.

Reduction

Gain of electrons (or hydrogen) by a molecule; reduction state increases.

Redox reaction

A coupled oxidation-reduction reaction where electrons are transferred between molecules.

NAD+/NADH

Nicotinamide adenine dinucleotide; NAD+ accepts electrons to become NADH; key electron carrier.

FAD/FADH2

Flavin adenine dinucleotide; FAD accepts electrons to become FADH2; another electron carrier.

Electron carrier

Molecules like NADH and FADH2 that transport electrons to the electron transport chain.

Glycolysis

First step of carbohydrate metabolism; occurs in cytoplasm; splits glucose into two pyruvate; net 2 ATP and 2 NADH.

Pyruvate

Three-carbon end product of glycolysis; substrate for the intermediate step.

Acetyl-CoA

Two-carbon molecule that enters the citric acid cycle after the intermediate step.

Intermediate step

Pyruvate oxidation to acetyl-CoA; releases CO2; generates NADH; occurs in the mitochondrial matrix (eukaryotes).

Citric acid cycle

Krebs or TCA cycle; oxidizes acetyl-CoA to CO2; yields NADH, FADH2, and ATP/GTP; occurs in mitochondria.

Oxaloacetate

Four-carbon molecule that combines with acetyl-CoA to start the citric acid cycle; regenerated at cycle end.

Isocitrate

Six-carbon intermediate in the citric acid cycle after rearrangement from citrate.

Carbon dioxide

Waste gas released during decarboxylation steps in metabolism.

NADH

Reduced NAD+; carries electrons to the electron transport chain.

FADH2

Reduced FAD; carries electrons to the electron transport chain.

Electron Transport Chain

Series of membrane proteins that transfer electrons and pump protons to create a proton gradient; final acceptor is oxygen in aerobic respiration.

ATP synthase

Enzyme that uses the proton gradient to synthesize ATP from ADP and Pi.

Proton motive force

Electrochemical gradient of protons across a membrane that drives ATP synthesis.

Chemiosmosis

Movement of protons down their gradient through ATP synthase to generate ATP.

Aerobic respiration

Cellular respiration that uses oxygen as the final electron acceptor, yielding more ATP.

Anaerobic respiration

Cellular respiration using non-oxygen final electron acceptors; same phases but different final acceptors.

Fermentation

Anaerobic process that regenerates NAD+ by transferring electrons to organic molecules when ETC is unavailable.

Lactic acid fermentation

Pyruvate accepts electrons to form lactate; regenerates NAD+.

Ethanol fermentation

Pyruvate is converted to acetaldehyde and then to ethanol; regenerates NAD+.

Beta-oxidation

Catabolic breakdown of fatty acids into acetyl-CoA units; yields NADH and FADH2.