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Chapter 8
Chapter 8
Chapter 8
Chapter 8
Chapter 8
Chapter 8
Chapter 8
Chapter 8
Chapter 8
Chapter 8
Chapter 8
Chapter 8
Chapter 8
Chapter 8
Chapter 8
Chapter 8
Chapter 8
Chapter 8
Chapter 8
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Chapter 8

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Chapter 8 Powerpoint

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    • 1.
      • Chapter 8
      • An Introduction to Metabolism
    • 2.
      • I. Energy: The capacity to do work. The ability to change matter
      • Can exist in two forms:
        • 1. Kinetic energy : Energy of motion. Energy that is actively performing work. Examples:
          • Heat : Energy of particles in motion.
          • Light : Energy of photons of light
        • 2. Potential energy : Stored energy due to position or arrangement of matter. Examples:
          • Chemical energy : Potential energy of molecules due to the arrangement of atoms. The most important type of energy for living organisms.
          • Position : Bicycle at the top of a hill.
    • 3.
      • Kinds of Energy
        • Electromagnetic
        • Chemical
        • Nuclear
        • Light
        • Mechanical
        • Electrical
        • Heat
        • Sound
    • 4.
      • II. Energy Transformation
      • Energy can be converted from one kind to another. Transformations are inefficient , generating heat.
      • Examples :
        • Light energy -------- --> Chemical energy (sugar) + Heat
        • Chemical energy -- ---> Mechanical energy + Heat
        • Electrical energy --- --> Light energy + Heat
        • Chemical energy --- --> Biological work + Heat
      • Heat is easily measured energy, because all other forms of energy can be converted to heat.
      • From a biological standpoint, heat is a poor kind of energy which is not very useful to do work.
      • Why? Because heat is lost to the environment.
    • 5.
      • III. All energy transformations are subject to the First and Second Laws of Thermodynamics
        • 1. First Law of Thermodynamics : Energy can be transformed (e.g.: chemical to mechanical), but cannot be created nor destroyed. The total amount of energy in the universe is constant .
        • Biological Consequence : Living organisms cannot create the energy they need to live. They must capture it from their environment.
        • Sources of energy used by living organisms : Sun and chemical energy.
    • 6.
      • 2. Second Law of Thermodynamics
      • ENERGY CONVERSIONS ARE INEFFICIENT
      • In any energy transformation, a certain amount of energy is lost as heat.
      • By comparison, living organisms are relatively efficient.
      • Electrical Energy -------> ---------> 5% Light + 95% Heat
      • Chemical Energy --> ----------------> 25% Mechanical
      • (Gasoline) 75% Heat
      • Chemical Energy --------> -----------> 40% ATP + 60% Heat
      • (Glucose)
    • 7.
      • III. Laws of Thermodynamics (Cont.)
        • 2. Second Law of Thermodynamics : Energy conversions reduce the order of the universe, because heat is dispersed into the environment.
        • As a result, the universe inevitably tends toward a state of increased disorder or chaos ( entropy ). Entropy (S) : Measure of disorder.
        • Disorganized, less usable energy (heat).
        • Heat is random molecular motion, a form of entropy.
        • Biological Consequences : Living organisms must constantly take in energy to avoid entropy (disintegration, death and decay).
        • High quality energy is a limited resource, because usable energy, decreases over time.
    • 8.
      • IV. Chemical Reactions Either Store or Release Energy :
      • I. Exergonic Reactions :
      • Release free energy.
      • Also exothermic (release heat).
      • Products have less energy than the reactants.
      • Example :
      • Cellular respiration is an exergonic process:
      • C 6 H 12 O 6 + 6 O 2 ----> 6 CO 2 + 6 H 2 O + Energy
      • Sugar Oxygen Carbon Water
      • Dioxide
      • High Energy Reactants Low Energy Products
    • 9. Change in Free Energy of a System:
      •  G =  H - T  S
      •  G is Gibb’s Free Energy or the energy available to do work.
      •  H is the total energy.
      • T is the temperature in Kelvin.
      •  S is entropy
      • Exergonic Reactions,  G -
      • Endergonic Reaction,  G +
    • 10.
      • IV. Chemical Reactions Store or Release Energy :
      • II. Endergonic Reactions :
      • Require net input of free energy.
      • Also endothermic (absorb heat).
      • Products have more energy than the reactants.
      • Create products that are rich in potential energy.
      • Example :
      • Photosynthesis is an endergonic process:
      • 6 CO 2 + 6 H 2 O + Sunlight ----> C 6 H 12 O 6 + 6 O 2
      • Carbon Water Energy Sugar Oxygen
      • Dioxide
      • Low Energy Reactants High Energy Products
    • 11. Chemical Reactions Either Store or Release Energy Endergonic Reactions Exergonic Reactions Require Energy Release Energy Higher Energy Products Lower Energy Products
    • 12.
      • Metabolism : All chemical processes that occur within a living organism. Either catabolic or anabolic reactions.
      • I. Catabolic Reactions :
        • Release energy ( exergonic ).
        • Break down large molecules (proteins, polysaccharides) into their building blocks (amino acids, simple sugars).
        • Often coupled to the endergonic synthesis of ATP.
        • Examples :
        • 1. Cellular respiration is a catabolic process:
        • C 6 H 12 O 6 + 6 O 2 -------> 6 CO 2 + 6 H 2 O + Energy
        • Sugar Oxygen Carbon dioxide Water
        • 2. The digestion of sucrose is a catabolic process:
        • Sucrose + Water -------> Glucose + Fructose + Energy
        • Disaccharide Monosaccharides
    • 13.
      • Metabolism: Catabolism + Anabolism
      • II. Anabolic Reactions :
        • Require energy ( endergonic ).
        • Build large molecules (proteins, polysaccharides) from their building blocks (amino acids, simple sugars).
        • Often coupled to the exergonic breakdown or hydrolysis of ATP.
        • Examples :
        • 1. Photosynthesis is an anabolic process:
        • 6 CO 2 + 6 H 2 O + Sunlight ----> C 6 H 12 O 6 + 6 O 2
        • Carbon Water Sugar Oxygen
        • Dioxide
        • 2. Synthesis of sucrose is an anabolic process:
        • Glucose + Fructose + Energy -------> Sucrose + H 2 O
        • Monosaccharides Disaccharide
    • 14.  
    • 15.
      • V. ATP: Shuttles Chemical Energy in the Cell
        • Coupled Reactions :
          • Endergonic and exergonic reactions are often coupled to each other in living organisms.
          • The energy released by exergonic reactions is used to fuel endergonic reactions.
        • ATP “shuttles” energy around the cell from exergonic reactions to endergonic reactions .
          • One cell makes and hydrolyzes about 10 million ATPs/second.
          • Cells contain a small supply of ATP molecules (1-5 seconds ).
        • ATP powers nearly all forms of cellular work:
          • 1. Mechanical work : Muscle contraction, beating of flagella and cilia, cell movement, movement of organelles, cell division.
          • 2. Transport work: Moving things in & out of cells.
          • 3. Chemical work : All endergonic reactions.
    • 16.
        • A. Structure of ATP (Adenosine triphosphate)
          • Adenine : Nitrogenous base.
          • Ribose : Pentose sugar, same ribose of RNA.
          • Three Phosphate groups: High energy bonds .
        • B. ATP Releases Energy When Phosphates Are Removed:
        • Phosphate bonds are rich in chemical energy and easily broken by hydrolysis :
        • ATP + H 2 O ----> ADP + Energy + P i
        • ADP + H 2 O ----> AMP + Energy + P i
    • 17. Structure and Hydrolysis of ATP
    • 18.
        • C. Regeneration of ATP :
        • ATP can be regenerated through dehydration synthesis :
        • ADP + Energy + P i ----> ATP + H 2 O
        • Phosphorylation : Transfer of a phosphate group to a molecule. Requires energy.
        • The energy required for this endergonic reaction is obtained by trapping energy released by other exergonic reactions
        • (E.g.: Cellular respiration).
    • 19. ATP Shuttles Energy From Exergonic Reactions to Endergonic Reactions

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