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Nutrient Role in Bioenergetics. Chapter 4. Bioenergetics. Bioenergetics refers to the flow of energy within a living system. Energy is the capacity to do work. Aerobic reactions require oxygen. Anaerobic reactions do not require oxygen. Bioenergetics. - PowerPoint PPT Presentation
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Nutrient Role in Bioenergetics
Chapter 4
Bioenergetics
Bioenergetics refers to the flow of energy within a living system.
Energy is the capacity to do work. Aerobic reactions require oxygen. Anaerobic reactions do not require
oxygen.
Bioenergetics
First law – Energy is neither created nor destroyed, but instead, transforms from one state to another without being used up.
Bioenergetics
There are six forms of interchangeable energy states:• Chemical• Light • Electric• Mechanical• Heat • Nuclear
Bioenergetics
The process of photosynthesis is a chemical reaction.
Chlorophyll absorbs radiant energy: To synthesize glucose from carbon
dioxide and water To release oxygen.
Solar energy and photosynthesis provide power to the animal world through food and oxygen.
Bioenergetics
Photosynthesis
What is the equation for the chemical reaction of photosynthesis?
Bioenergetics
Respiration is the reverse of photosynthesis.
C6H12O6 + O2 → 6CO2 + 6H2O
Cellular Respiration
Organism transforms the chemical energy into a form it can use. Cellular Respiration-Step by step process
Glucose Lipids Amino acids
Heat
Bioenergetics
Takes one of three forms:• Mechanical work of muscle contraction• Chemical work for synthesizing cellular
molecules• Transport work that concentrates diverse
substances in body fluids
Bioenergetics
Potential energy Energy associated with a substance’s
structure or position. Kinetic energy
Energy of motion. Potential energy and kinetic energy
The total energy of any system.
Bioenergetics
Adenosine Triphosphate
Bioenergetics
Cellular Oxidation–Reduction Reactions Constitute the mechanism for energy
metabolism Redox reactions power the transfer
process of energy
Bioenergetics
Oxidation–reduction reactions couple:• Oxidation = a substance loses electrons
Transfer oxygen, hydrogen, or electrons
• Reduction = a substance gains electrons Atoms gain an electron-reducing valence
Coupled Reactions
Coupled Reactions
Reduction Reaction 2C3H4O3 + 2H → 2C3H6O3
LDH
Pyruvate (gains 2 e-) → Lactate
Coupled Reactions
Oxidation Reaction 2C3H6O3 - 2H → 2C3H4O3
LDH
Lactate (loses 2 e-) Pyruvate
Bioenergetics
ATP – energy currency Potential energy extracted from food
ATP Chemical energy extracted for biologic
work Cells Muscle contraction
Phosphate Bond
Stored or potential energy High energy bonds ATP – hydrolysis
ATP + H2O → ADP + P – 7.3 kCal/mole ATPase
Bioenergetics
Bioenergetics
Phosphocreatine (PC) is also a high-energy phosphate compound. ATP-PC (phosphagens) Releases energy when bonds between
creatine and phosphate are broken. Sustains all out exercise ~ 5-8 s Resynthesis of ATP used – reservoir Stored in muscle - anaerobic
Bioenergetics
Cells store 4-6 times more PCr than ATP Muscle
Provide a reservoir of high-energy phosphate bonds ATP + H2O ADP + Pi
ATPase
ADP + C~P ATP + C Creatine kinase
Bioenergetics
Phosphorylation Refers to energy transfer through
phosphate bonds Oxidative phosphorylation
Synthesizes ATP by transfer of electrons NADH and FADH2
Cellular Oxidation-Reduction Reactions
Mechanism for energy metabolism Involves transfer of hydrogen atoms
Loss of hydrogen: oxidation Gain of hydrogen: reduction
Cellular Oxidation
Mitochondria NAD and FAD → NADH and FADH2
Cytochromes – Electron Transport Chain (ETC)
Transfer of electrons (H+) Energy conserved – high energy phosphate
bonds Figure 4.11
Bioenergetics
Sources for ATP formation include:• Glucose derived from liver glycogen
Glycogenolysis Triacylglycerol and glycogen stored in muscle
• Free fatty acids - circulating Triacylglycerol in liver, adipocytes Lipoprotein complexes - circulating
• Amino acids Intramuscular and liver-derived carbon skeletons
Bioenergetics