Energy

Energy Chapter 8 –Oxidation-Reduction –ATP

Oxidation-Reduction What is a covalent bond?

Oxidation-Reduction Is it easy to form?

Oxidation-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-Reduction Chemical reactions involve transferring energy stored in chemical bonds to new bonds Electrons can also be transferred during chemical reactions

Oxidation-Reduction Oxidation: The process by which an atom loses an electron

Oxidation-Reduction Reduction: The process by which an atom gains an electron

Oxidation Oxygen attracts electrons Often accepts electrons during cellular processes

Oxidation Oxygen attracts electrons Often accepts electrons during cellular processes Oxidation is oxygen “stealing” an electron from the atom of interest

Reduction What charge does an electron carry?

Reduction If an atom gains an electron what happens to the charge of that atom?

Reduction When an atom gains an electron its charge becomes more negative aka. that atom is reduced

Oxidation-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-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-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-Reduction Electrons can gain energy by moving further from the nucleus Moved by light or other energy

Oxidation-Reduction When energized electrons move to another atom they take that energy with them

Oxidation-Reduction The energy can be released by moving the electron back to its original distance from the nucleus

Oxidation-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

Energy Process ☼ Oxidation-Reduction –ATP

ATP Adenosine Triphosphate

ATP Structure

ATP

ATP

ATP Energy is stored in the bonds between the phosphate groups Energy is released when the bonds are broken

ATP The resulting molecule (ADP) can have phosphate groups re-attached to be used again

ATP 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 + P i 7 kcal ATP 7 kcal