Download Metabolism

Metabolism
Metabolism
Total of all chemical reactions that occur in
the body
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1. Anabolic reactions
9 Synthesis of molecules
2. Catabolic reactions
9 Breakdown of molecules
Bioenergetics
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•
Converting foodstuffs (fats, proteins,
carbohydrates) into “harnessed” energy
9 ATP
Food
Food
O2
Uncontrolled oxidation of
food outside the body
(burning)
O2
Controlled oxidation of
food inside the body
ATP
Explosive release
of energy as heat
Energy harnessed as ATP
Energy released
as heat
ATP
ATP
Partly used to maintain
body temperature
Excess heat
eliminated to the
environment
Figure 2.14 Page 41
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Metabolism rates are determined by…
Enzymes
• Function as Biological Catalysts
• Enzymes speed up chemical reactions without
altering the energy release of that reaction
• Determine which energy pathways are best for the
particular cellular activity
9Food breakdown
9Jogging
9Sprinting
Enzymes make it easier for reactions to occur!
Where do we get our energy?
Carbs, Proteins, Fats
What is the form of energy we
use in our bodies?
ATP
What do we do with the
energy we don’t use?
Expend it as heat
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ATP & Energy Systems
Energy currency of the body
Adenosine triphosphate (ATP)
• Consists of adenine, ribose, and three linked
phosphates
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Formation ADP + Pi → ATP
• Addition of Pi; Phosphorylation
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Breakdown ATP
ATPase
ADP + Pi + Energy
• ATP splitting; Hydrolysis
ATP Regeneration
3-ways:
1. Interaction of ADP and PC
9 ADP = adenosine diphosphate
9 PC = creatine phosphate or phosphocreatine (CrP)
2. Anaerobic respiration in cell cytoplasm
9 Not using O2
3. Aerobic respiration in mitochondria
9 Using O2
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Anaerobic Energy Systems
1.
Phosphagen systems
2.
Glycolysis
Anaerobic Energy Systems
1) Phosphagen System (in cytosol):
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Immediate energy sources
Creatine Kinase
CrP + ADP + H+
Creatine +
ATP
Adenylate Kinase
ADP
¾
+ ADP
ATP
+
AMP
Concentrations will drive reaction
• ~ 10 seconds worth of energy
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AMP build-up stimulates gylcolysis
Anaerobic Energy Systems (cont.)
2) Glycolysis (in cytosol):
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Prepares glucose to enter next stage of
metabolism
• Glucose to Pyruvate
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10 or 11 step process (for 1 glucose molecule)
• Begins with glucose (11) or glycogen (10)
9Occurs in Cytoplasm
9From liver, muscle or blood
9 Facilitated diffusion across muscle membrane
4
HK
GLYCOGEN
PFK
2 ATP
Formed
2 Pyruvic
Acid
Molecules
What to know about Glycolysis…
Anaerobic energy system (in cytosol)
1.
•
No O2
10 (glycogen) or 11 (glucose) steps:
2.
•
Rate of glycolysis may increase or decrease
depending on:
9 Amount of available ATP
9 Amount of available glycogen or glucose
9 HK and PFK
End result = 2 ATP, 2 Pyruvic Acid
3.
•
Pyruvic acid either enters mitochondria or turned
into lactic acid
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Aerobic Energy Systems
1.
Citric acid cycle
2.
Electron transport chain
Aerobic Energy System
Phosphagen
Systems
Glycolysis
Glycolysis to the Mitochondria
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Pyruvate can either:
• Form lactic acid
• Selectively transported into the mitochondria
2 major events:
1) H+ picked up by
NAD
2) Formation of
Acetyl CoA
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Acetyl CoA enters the Citric Acid Cycle…
Citric Acid Cycle (Krebs or TCA) produces…
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8 step process after pyruvate turned into
Acetyl CoA
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2 CO2
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3 H+ picked up by NAD
• 1 H+ picked up by FAD
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1 ATP produced and used immediately in cell
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No O2 used, but requires presences of O2 to
operate
Electron Transport Chain
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A.K.A. ~ Oxidative phosphorylation
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Citric acid cycle prepares H+ carriers for ETC
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NADH and FADH enter ETC
• Major source of energy!
• Electrons held by NAD and FAD are “high
energy”
9Transferred through a series of steps from one electron
carrier to another
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Electron carriers in mitochondria:
• Electrons (from NAD & FAD) fall to successively
lower energy levels with each step
• Throughout process electrons release energy
9Used to create ATP
• End by binding with O2 and forming water
• Entire process creates 32 ATP molecules
In Summary…
Anaerobic conditions
}
No O2
available
Glycolysis
Pyruvic acid
Glucose
Mitochondrial outer
and inner membranes
Lactic acid
2 ATP
Aerobic conditions
Glycolysis
Glucose
O2 available
Pyruvic acid
34 ATP + CO2 + H2O
Citric acid Electron transport
cycle
chain
2 ATP
Cytosol
Mitochondrion
Figure 2.15
Page 41
Cellular Respiration
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Energy transfer
• Food to ATP
• Aerobic or Anaerobic
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Major nutrients serve as fuel substrates
• Carbohydrates
9Glucose
• Fats (Triglycerides)
9Free fatty acids
• Proteins
9Amino acids
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Fat & Protein Breakdown
Questions?
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