Redox chemistry involves the transfer of electrons from one reactant to another. Reducing agents donate electrons while oxidizing agents accept electrons. Biological redox systems, like cytochromes, are important for cellular functions such as forming water from hydrogen. Cytochromes undergo one electron redox reactions and participate in electron transport chains, transferring electrons from reduced flavoproteins to oxygen to form water. Many biological redox systems are pH dependent, and electrode potentials are typically listed at pH 7.0 for comparisons. Other important redox systems include NADH/NAD, flavins, and various substrate systems.

1. Redox chemistry
Halavath Ramesh
Loyola college-Chennai

2. 1. Oxidation / reduction reactions are sometimes called redox reactions.
2. A reducing agent is an electron donor. An oxidizing agent is an electron
acceptor.
3. In an oxidation/reduction reaction electrons are transferred from one
reactant to another.
4. A cathode is an electrode where reduction occurs. An anode is an electrode
where oxidation occurs.
5. Galvanic cells store electrical energy
6. Electrolytic cells consume electricity
7. Reduction take place at the cathode
8. Oxidation always takes place at the anode
Introduction

3. The phase boundary between an electrode and its solution is called an Interface. In a
cell electricity is carried by the movement of ions. Both anions and cations
contribute.
Biological Redox Systems:
There are many redox systems of importance in biology and biochemistry. The
Cytochromes are excellent examples of such systems. Cytochromes are iron-heme
proteins in which a porphyrin ring is coordinated through nitrogen atoms to an iron
atom. These under goes one electron redox reactions. The physiological functions of
Cytochromes are intimate participants in the formation of water from H2 . Reduced
pyridine nucleotide deliver hydrogen to flavoproteins.The reduced flavoproteins.The
are reoxidized by the Fe3+ of Cytochrome b or c. The result is the formation of H+
and the transport of electrons. The chain is completed when Cytochrome oxidase
transfers electrons to oxygen. The resulting oxide ion (o2-) is unstable and
immediately picks up two H+ ions to produce H2O.

4. Most biological redox systems are pH dependent. It
has become standard practice to list the electrode
potentials of these systems at pH 7.0 in order to make
comparisons of oxidizing or reducing powers. The
values listed are typically formal potential at pH7.0
Other redox systems of importance in
biochemistry include the NADH/NAD system, the
flavins, the pyruvate / lactate system, the oxalacetate
/malate system and the quinone /hydroquinone system.

5. Thank you