glycolysis vs gluconeogensis

what enzymes do glycolysis and gluconeogensis shared

• Aldolase

• Triose phosphate isomerase

• Glyceraldehyde-3-phosphate dehydrogenase

• Phosphoglycerate kinase

• Phosphoglycerate mutase

• Enolase

what enzymes do glycolysis and gluconeogensis NOT share (irreversible steps)

Glycolysis:

• Hexokinase (or glucokinase in liver)

• Phosphofructokinase-1 (PFK-1)

• Pyruvate kinase

Gluconeogenesis bypass enzymes:

• Glucose-6-phosphatase

• Fructose-1,6-bisphosphatase

• Pyruvate carboxylase

• PEP carboxykinase (PEPCK)

Enzyme bypass pairs

• Hexokinase → Glucose-6-phosphatase

• PFK-1 → Fructose-1,6-bisphosphatase

• Pyruvate kinase → Pyruvate carboxylase + PEPCK

what is the rate limiting step of glycolysis and gluconeogensis

• Glycolysis → PFK-1

• Gluconeogenesis → Fructose-1,6-bisphosphatase

Regulation (ATP, AMP, citrate)

• High ATP → ↓ glycolysis, ↑ gluconeogenesis

• High AMP → ↑ glycolysis, ↓ gluconeogenesis

• Citrate → inhibits glycolysis

ATP usage vs production

• Glycolysis → produces ATP (net 2 ATP)

• Gluconeogenesis → consumes ATP (4 ATP + 2 GTP)

 Net yield

• Glycolysis → 2 ATP, 2 NADH

• Gluconeogenesis → uses 6 high-energy phosphates total

Tissue location

• Glycolysis → all cells

• Gluconeogenesis → liver (main), kidney (minor)

Cellular location

• Glycolysis → cytosol

• Gluconeogenesis → mitochondria + cytosol + ER (final step)

Fed vs fasting

• Fed → glycolysis ON

• Fasting → gluconeogenesis ON

 Direction of pathway

• Energy needed → glycolysis

• Glucose needed → gluconeogenesis

Cori cycle

from glycolysis. Muscle → lactate → liver

• Liver converts lactate → glucose

Anabolic vs catabolic

• Glycolysis → catabolic

• Gluconeogenesis → anabolic

 Starvation/exercise

• Starvation → gluconeogenesis

• Exercise → glycolysis (and fermentation if anaerobic)

Identify pathway from intermediates

• Glucose → pyruvate → glycolysis

• Pyruvate → glucose → gluconeogenesis