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Energy Energy
EnergyEnergy
EnergyEnergy
• Chapter 8– Oxidation-Reduction– ATP
Oxidation-ReductionOxidation-Reduction
• What is a covalent bond?
Oxidation-ReductionOxidation-Reduction
• What is a covalent bond?
• Is it easy to form?
Oxidation-ReductionOxidation-Reduction
• Energy is stored in the bonds between atoms– Most energy on earth comes from the sun– Photosynthesis is the process by which the
sun’s energy is converted into stored in bonds between atoms in complex sugar molecules
Oxidation-ReductionOxidation-Reduction
• Chemical reactions involve transferring energy stored in chemical bonds to new bonds
• Electrons can also be transferred during chemical reactions
Oxidation-ReductionOxidation-Reduction
• Oxidation: The process by which an atom loses an electron
Oxidation-ReductionOxidation-Reduction
• Oxidation: The process by which an atom loses an electron
• Reduction: The process by which an atom gains an electron
OxidationOxidation
• Oxygen attracts electrons
• Often accepts electrons during cellular processes
OxidationOxidation
• Oxygen attracts electrons
• Often accepts electrons during cellular processes
• Oxidation is oxygen “stealing” an electron from the atom of interest
ReductionReduction
• What charge does an electron carry?
ReductionReduction
• What charge does an electron carry?
• If an atom gains an electron what happens to the charge of that atom?
ReductionReduction
• When an atom gains an electron its charge becomes more negative
• aka. that atom is reduced
Oxidation-ReductionOxidation-Reduction
• Electrons are never lost entirely: they just exchange ownership
• Oxidations and reductions always take place together
• Reactions of this nature are referred to as Redox reactions
Oxidation-ReductionOxidation-Reduction
• Redox reactions are the process by which energy is transferred between molecules
• The reduced form of a molecule has a higher energy than the oxidized form
Oxidation-ReductionOxidation-Reduction
• Electrons carry energy with them when they pass from molecule to molecule
• Energy possessed by an electron depends on the distance between the electron and the nucleus of the atom
Oxidation-ReductionOxidation-Reduction
• Electrons can gain energy by moving further from the nucleus
• Moved by light or other energy
Oxidation-ReductionOxidation-Reduction
• When energized electrons move to another atom they take that energy with them
Oxidation-ReductionOxidation-Reduction
• When energized electrons move to another atom they take that energy with them
• The energy can be released by moving the electron back to its original distance from the nucleus
Oxidation-ReductionOxidation-Reduction
• Our studies describe critical cell processes which rely on the energy from redox reactions
• These processes are the keys to life on this planet
EnergyEnergy
• Process☼ Oxidation-Reduction– ATP
ATPATP • Adenosine Triphosphate
ATPATP
• Structure
ATPATP
• Structure
ATPATP
• Structure
ATPATP
• Energy is stored in the bonds between the phosphate groups
• Energy is released when the bonds are broken
ATPATP
• The resulting molecule (ADP) can have phosphate groups re-attached to be used again
ATPATP
• There are 7 kcal energy stored one bond between phosphate groups– 7 kcal are released
when the bond is broken
– 7 kcal are required to form the bond
ADP + Pi
7 kcal7 kcal
ATP
7 kcal7 kcal
