Ch 14 Glycolysis, Gluconeogenesis, Pentose Pathway

Glycolysis

10-step pathway breaking down glucose into pyruvate.

Gluconeogenesis

Pathway synthesizing glucose from non-carbohydrate sources.

Pentose Phosphate Pathway

Alternative pathway oxidizing glucose 6-phosphate.

ATP

Cell's energy currency produced during glycolysis.

NADH

Carries high-energy electrons, essential for energy metabolism.

Preparatory Phase

First 5 glycolysis steps using 2 ATP.

Payoff Phase

Last 5 glycolysis steps producing 4 ATP and 2 NADH.

Substrate-Level Phosphorylation

ATP formation via direct transfer of phosphate.

Exergonic Reaction

Releases energy, as seen in glucose breakdown.

Endergonic Reaction

Requires energy input, as in ATP synthesis.

Phosphorylated Intermediates

Prevent glucose derivatives from leaving the cell.

Fermentation

Anaerobic process regenerating NAD+ from pyruvate.

Lactic Acid Fermentation

Converts pyruvate to lactate, regenerating NAD+.

Alcohol Fermentation

Converts pyruvate to ethanol and CO2, regenerating NAD+.

Glycogen

Stored polysaccharide broken down into glucose.

Hexoses

Simple sugars like glucose entering glycolysis.

Gluconeogenic Amino Acids

Amino acids converted to glucose precursors.

Irreversible Steps

Three glycolytic steps bypassed in gluconeogenesis.

Glucose 6-Phosphatase

Enzyme converting glucose 6-phosphate to glucose.

Fructose 1,6-Bisphosphatase

Enzyme converting fructose 1,6-bisphosphate to fructose 6-phosphate.

Pyruvate Carboxylase

Converts pyruvate to oxaloacetate in gluconeogenesis.

Phosphoenolpyruvate Carboxykinase

Converts oxaloacetate to PEP in gluconeogenesis.

Energetic Cost of Gluconeogenesis

Requires 4 ATP, 2 GTP, and 2 NADH.

Fructose 2,6-Bisphosphate

Regulates glycolysis and gluconeogenesis reciprocally.

Insulin

Hormone increasing fructose 2,6-bisphosphate levels.

Glucagon

Hormone decreasing fructose 2,6-bisphosphate levels.

Ribose 5-Phosphate

Produced in pentose phosphate pathway, essential for nucleotides.

NADPH

Reduced cofactor crucial for biosynthetic reactions.

Overall Equation of Glycolysis

glucose + 2NAD+ + 2ADP + 2Pi → products.

Overall Equation of Pentose Pathway

glucose 6-phosphate + 2NADP+ + H2O → products.

Oxidative Phosphorylation

ATP production linked to electron transport chain.