Download Metabolic Pathways and Energy Production

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
Anabolic reactions
• Use small molecules to build large ones
• Require energy
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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
adenosine diphosphate
ADP
O
-
O
O
O
-
O
N
O
N
P O P O P O CH2
-
NH2
-
N
adenine
N
O
O
ribose
OH
OH
adenosine triphosphate ATP
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Digestion of Foods
Digestion is the first step of catabolism
• Carbohydrates
glucose, fructose,
galactose
• Proteins
amino acids
• 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
P O CH2
HO CH2
O
OH
CH2 O P
O
PO4
OH
HO
OH
OH
OH
glucose
OH
fructose-1,6-diphosphate
CHO
2
H C OH
CH2O P
2 glyceraldehyde-3-phosphate
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Glycolysis: Oxidation of
Glucose
2 ADP + 2 Pi
2 ATP
CHO
CHO
2
2
H C OH
H C O
CH3
CH2O P
2 glyceraldehyde-3-phosphate
2 NAD+
2 pyruvate
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
||
CH3–C –COO- + NADH + H+
OH
|
CH3–CH –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
(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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