# 0.21 Bis2a 06.1 red/ox in metabolism v1.2

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In this module we will review Red/Ox reactions and relate them to metabolic process. We will introduce the electron tower, a tool to be used to understand red/ox half reactions and the energy associated with different reactions.

## Red/ox reactions in biology

Earth’s atmosphere contains about 20% molecular oxygen, O 2 , a chemically reactive gas that plays an essential role in the metabolism of aerobic organisms and in many environmental processes that shape the world. The term oxidation was originally used to describe chemical reactions involving O 2 , but its meaning has evolved to refer to a broad and important reaction class known as oxidation-reduction (red/ox) reactions . Our current working definition of oxidation is based on the ability of a compound to lose electrons, and removes all references to the involvement of molecular oxygen. A few examples of such reactions will be used to develop a clear picture of this classification of essential biochemical reactions.

The chemical reactions underlying metabolism involve the transfer of electrons from one compound to another by processes catalyzed by enzymes. The electrons in these reactions commonly come from hydrogen atoms, which consist of an electron and a proton. A molecule gives up a hydrogen atom, in the form of a hydrogen ion or proton, (H + ) and an electron, breaking the molecule into smaller parts. During the loss of an electron(s), or oxidation from one compound, the elctron(s) are then passed to another molecule in a process called reduction , or the gaining of an electron. These two reactions always happen together in an oxidation-reduction reaction (also called a red/ox reaction)—when electrons are passed between two molecules, the donor molecule is oxidized and the recipient molecule is reduced. These reactions are exergonic    . Remember, an exergonic reaction is a chemical reaction where the change in the free energy is negative (there is a net release of free energy), indicating a spontaneous reaction. Oxidation-reduction reactions often happen in a series: A molecule that has just been reduced may be very quickly re-oxidized, passing on an electron to a new acceptor.

Remember the definitions of oxidation and reduction :

$\begin{array}{lll}\hfill \mathbf{\text{oxidation}}& =& \text{loss of electrons}\hfill \\ \hfill \mathbf{\text{reduction}}& =& \text{gain of electrons}\hfill \end{array}$

Also remember, that if a compound is oxidized another compound must be reduced. The two process go together. The electrons have to go somewhere, we can not have free floating electrons in our system, they must be associated with a molecule or atom. This is an essential concept.

## Red/ox in metabolism

One of the primary sources of cellular energy comes from Oxidation-Reductions reactions, termed red/ox . During the movement of electrons from one molecule to a second, energy is released, and that energy can be used to work (translocate protons) or be stored (ATP synthesis) for future work. This is true as long as the electrons are passed from one compound to a second compound with a higher reduction potential , that is a compound that has a higher affinity for those electrons. The concept of reduction potential is explained below.

#### Questions & Answers

how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Good
what does post-translational control refer to?
Teresa Reply
Bioremediation includes
Rachel Reply

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Source:  OpenStax, Ucd bis2a intro to biology v1.2. OpenStax CNX. Sep 22, 2015 Download for free at https://legacy.cnx.org/content/col11890/1.1
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