Metabolic Pathways and Energy Production

1
Metabolic Pathways and Energy Production

• Metabolism and ATP Energy
• Important Coenzymes
• Glycolysis

2
Metabolism

• All the chemical reactions that occur in the
  cells of our bodies.
• Catabolic reactions
• Break down large molecules
• Provide energy for ATP
• Anabolic reactions
• Use small molecules to build large ones
• Require energy

catabolic
anabolic
3
Cell Structure

• Typical animal cell
• Nucleus
• Chromosomes in the nucleus contain genetic
  material
• Cytoplasm is material between nucleus and cell
  membrane
• Mitochondria are where energy-producing reactions
  occur

4
ATP

• Energy is released as food is oxidized
• Used to form ATP from ADP and Pi
• ADP Pi Energy ATP
• In cells, energy is provided by the hydrolysis of
  ATP
• ATP ADP Pi Energy

5
Structure of ATP
6
Digestion of Foods

• Digestion is the first step of catabolism
• Carbohydrates glucose, fructose, galactose
• Proteins amino acids
• Lipids glycerol
• fatty acids

7
Coenzymes

• Substances that connect metabolic pathways
• In reduction, coenzymes accept H atoms
• In oxidation, coenzymes remove H atoms
• FAD (flavin adenine dinucleotide)
• FAD -CH2-CH2- FADH2 -CHCH-
• NAD (nicotinamide adenine dinucleotide)
• NAD -CH-OH NADH H -CO

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Glycolysis Oxidation of Glucose
Glucose

• 2ATP
• 2 NAD
• 2ADP 2NADH 2H
• 4 ADP
• 4 ATP

two Glyceraldehyde-3-PO4
two Pyruvate
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Glycolysis Oxidation of Glucose
10
Glycolysis Oxidation of Glucose

• 2 NAD 2 NADH 2 H

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Glycolysis Oxidation of Glucose

• Glycolysis generates
• 2 ATP molecules and 2 NADH 2 H
• Two ATP used in adding phosphate groups to
  glucose and fructose-6-phosphate (- 2 ATP)
• Four ATP generated in direct transfer to ADP by
  two 3-C molecules ( 4 ATP)
• Glucose 2 ADP 2 Pi 2 NAD
• 2pyruvate 2 ATP 2 NADH 2 H

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Pathways for Pyruvate

• Aerobic conditions
• O
• CH3C COO- NAD CoA
• pyruvate
• O
• CH3C CoA CO2 NADH H
• acetyl CoA

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Pathways for Pyruvate

• Anaerobic conditions (No O2 available)
• Reduce to lactate to replenish NAD for
  glycolysis
• O OH
• CH3C COO- NADH H CH3CH COO- NAD
• pyruvate lactate
• enzyme lactate dehydrogenase

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Lactate in Muscles

• Strenuous exercise leads to anaerobic conditions
• Oxygen in muscles is depleted
• Lactate builds up as glycolysis continues
• Muscles tire and become painful
• Breathing rate increases
• Rest repays oxygen debt
• Lactate re-forms pyruvate in liver

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Learning Check M1

• Match the following with the terms below
• (1) Catabolic reactions (2) Coenzymes
• (3) Glycolysis (4) Lactate
• A. Produced during anaerobic conditions
• B. Reactions that convert glucose to pyruvate
• C. Metabolic reactions that break down large
  molecules to smaller molecules energy
• D. Substances that remove or add H atoms in
  oxidation and reduction reactions

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Solution M1

• Match the following with the terms below
• (1) Catabolic reactions (2) Coenzymes
• Glycolysis (4) Lactate
• A. 4 Produced during anaerobic conditions
• B. 3 Reactions that convert glucose to pyruvate
• C. 1 Metabolic reactions that break down large
• molecules to smaller molecules energy
• D. 2 Substances that remove or add H atoms in
• oxidation and reduction reactions