Download 18.3 Important Coenzymes

Glycolysis
Metabolic Rx
• Many metabolic enzymes need
coenzymes to function
• Common coenzymes: NAD, FAD,
Coenzyme A, ATP
• These are nucleotide molecules
• accept/deliver electrons for redox
reactions
• accept/delivers phosphates to generate
ATP
NAD – Nicotinamide Adenine
Dinucleotide
ATP – Adenosine Triphosphate
ATP
• Energy currency of the cell
• Energy is stored between negatively
charged phosphates
• Rechargeable battery ADP + P → ATP
Coupled Rx Writing in
Metabolism
Dehydrogenase
Alcohol
Aldehyde
NAD
NADH
Enzyme
Substrate is oxidized
Coenzyme is reduced
Glycolysis
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Pathway of 10 interconnected enzyme Rx
Initial substrate: glucose
Final product: pyruvate
Most ancient metabolic pathway, evolved before
O2 levels were high and therefore….
• does not need O2, does not produce CO2
• Takes place in the cytosol of cells
• has an energy investing phase (activation E)
and energy yielding phase
Energy Summary of Glycolysis
• Per glucose molecule:
• Energy investing phase:
-2 ATP
invested/1 glucose
• Energy yielding phase:
+4ATP
• Net yield
+2 ATP
• Low net yield:
only 2 mole ATP/1 mole glucose!!!
Net Rx of Glycolysis
1 Glucose + 2 ATP + 2ADP + 2P + 2NAD →
2 Pyruvate + 4 ATP + 2NADH + 2H2O
Warm-up
Methandiol
Methanoic Acid
1. Rewrite the Rx with molecular structures
2. Rewrite the Rx and add NAD/NADH
coupled coenzyme arrow
3. Rewrite the Rx as a Redox Rx (integrate
the coupled arrow into the Rx)
• Glycolysis
• Crashcourse Overview respiration