EXSC 223 Chapter 24 The 2 Fates of Pyruvate

Two pathways of pyruvate

Aerobic and Anaerobic respiration

Aerobic respiration

Involves cellular respiration within mitochondria

Anaerobic respiration

Metabolites produced without oxygen involvement. Occurs in the cytoplasm

Anaerobic Pathway

• Anaerobic metabolism occurs regardless of oxygen presence; often produces lactate.

• Produced via lactate dehydrogenase (LDH) by converting pyruvate and burns NADPH.

• Lactate allows continued ATP production by recycling NAD needed for glycolysis

Lactate production

• Vital for maintaining ATP production to prevent cell death.

• Creates a NAD recycling program enabling ongoing glycolysis.

• Its accumulation slows down glycolysis

Aerobic pathway (mitochondrial function)

• Mitochondria present two membranes and have their own DNA.

• Process refers to pyruvate transport into the mitochondria and conversion to acetyl-CoA.

Conversion process (Aerobic pathway)

• Pyruvate dehydrogenase (PDH) (groups of enzymes) enzyme crosses the membrane. Moves pyruvate across the membrane

• Removes one carbon (producing CO2) and transfers hydrogens and electrons onto NAD (producing NADH). NADH transfers the hydrogens and electrons off the NAD in the cytosol to the intermembrane space to the mitochondria matrix

• Coenzyme A (CoA) is added to form acetyl-CoA (starts krebs cycle)

Acetyl-CoA

Crucial intermediate for the citric acid cycle.