Glucose Metabolism and Cellular Respiration

Vocabulary flashcards covering the stages, mechanisms, and key biochemical concepts of glucose metabolism and cellular respiration.

Metabolism

The sum of all the chemical reactions occurring within a cell, divided into catabolic and anabolic pathways.

Catabolic reactions

Reactions that break down nutrients to release energy stored in chemical bonds, capturing some of it in ATP and energy carriers while generating precursor molecules.

Anabolism

Energy-requiring reactions that build larger macromolecules from precursor molecules to carry out processes like growth, division, and repair.

Cellular respiration

A set of oxidation-reduction (redox) reactions that oxidize nutrients to produce ATP, eventually requiring oxygen in aerobic pathways.

Glycolysis

An anaerobic process in the cytoplasm that literally means 'splitting a sugar,' oxidizing one molecule of glucose into two molecules of pyruvate.

Hexokinase

The enzyme responsible for phosphorylating one molecule of glucose to generate glucose-6-phosphate during the first step of glycolysis.

Glucose-6-phosphate

A phosphorylated form of glucose that cannot leave the cell and serves as an 'on switch' dedicating the molecule to the glycolysis pathway.

Energy investment phase

The initial phase of glycolysis where two molecules of ATP are expended to phosphorylate and split the glucose molecule.

Energy payoff phase

The second phase of glycolysis that produces four molecules of ATP via substrate phosphorylation, two molecules of NADH, and two molecules of pyruvate.

Fermentation

An anaerobic pathway that oxidizes NADH back to $NAD^+$ without producing additional ATP, allowing glycolysis to continue in the absence of oxygen.

Alcoholic fermentation

An anaerobic pathway occurring in yeast where ethanol accepts electrons and forms ethanol (alcohol) as a waste product.

Lactic acid fermentation

An anaerobic pathway occurring in cells such as skeletal muscle where pyruvate acts as the electron acceptor, producing lactic acid as a waste product.

Acetyl CoA

The molecule formed from pyruvate during the one-reaction intermediate step after glycolysis before entering the Krebs cycle.

Krebs cycle

A cyclical series of eight enzyme-catalyzed reactions in the mitochondrial matrix that processes acetyl CoA to yield two ATP, six NADH, and two $FADH_2$ per glucose molecule.

Hans Krebs

The Nobel Prize-winning scientist who helped elucidate the cyclical metabolic pathway known as the citric acid or TCA cycle.

Electron transport chain

A sequential series of electron carriers embedded in the inner mitochondrial membrane that pass electrons through redox reactions to pump protons and create an electrochemical gradient.

Chemiosmosis

The process of establishing a chemical or electrochemical proton gradient of hydrogen ions across a semipermeable membrane.

Proton motive force

The potential energy gradient generated by the accumulation of positively charged hydrogen ions in the intermembrane space.

ATP synthase

A rotor-like membrane enzyme that utilizes the flow of returning hydrogen ions to catalyze the phosphorylation of ADP and phosphate into ATP.

Oxidative phosphorylation

The production of ATP fueled by a proton gradient created through the oxidation (loss of electrons) of NADH and $FADH_2$.