Metabolic Pathways and Energy Production
Metabolism and ATP Energy Important Coenzymes Glycolysis
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Metabolism
All the chemical reactions that occur in the cells of our bodies. Catabolic reactions • Break down large molecules • Provide energy for ATP
catabolic
Anabolic reactions • Use small molecules to build large ones • Require energy
anabolic
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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
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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
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Structure of ATP
a d e n o s in e d ip h o s p h a te AD P O O
-
NH2 N N N N
a d e n in e
O O
-
O O
-
P O
P O
P O
-
O
CH2
O rib o s e
OH a d e n o s in e trip h o s p h a te AT P
OH
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Digestion of Foods
Digestion is the first step of catabolism • Carbohydrates glucose, fructose, galactose amino acids
• Proteins
• Lipids
glycerol fatty acids
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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 + -CH=CH-
NAD+ (nicotinamide adenine dinucleotide)
NAD+
+ -CH-OH
NADH + H+ + -C=O
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Glycolysis: Oxidation of Glucose
Glucose
2ATP
2 NAD+
2ADP
two Glyceraldehyde-3-PO4
2NADH + 2H+ 4 ADP
two Pyruvate
4 ATP
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Glycolysis: Oxidation of Glucose
HO CH2 O OH OH OH g lu c o s e OH fru c to s e -1 ,6 -d ip h o s p h a te OH P P O4 O CH2 O HO OH CH2 O P
CHO 2 H C OH P
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C H 2O
2 g lyc e ra ld e h yd e -3 -p h o s p h a te
Glycolysis: Oxidation of Glucose
2 ADP CHO 2 H C OH P 2 H + 2 Pi 2 ATP CHO C O
C H 2O
CH3 2 p yru va te
2 g lyc e ra ld e h yd e -3 -p h o s p h a te
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 3C 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 || CH3–C –COO- + NAD+ + CoA pyruvate
O ||
CH3–C –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 |
CH3–C –COO- + NADH + H+ pyruvate
CH3–CH –COO- + NAD+ 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 15
Solution M1
Match the following with the terms below: (1) Catabolic reactions (2) Coenzymes (3) 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
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