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However, many other organisms, all of them microbes (and include bacterial, archaeal and eykaryotic members) can use other compounds as terminal electron acceptors. These other compounds include common ions as nitrate (NO 3 - ), reduction potential of +0.42, and nitrite (NO 2 - ), reduction potential of +0.72, or tetrathionate (S 4 O 6 2- ) reduction potential of +0.024. When the terminal electron acceptor is not molecular oxygen (O 2 ) then the process is considered anaerobic and is referred to as anaerobic respiration . The ability of an organism to vary its terminal electron acceptor provides metabolic flexibility and can ensure better survival if any given terminal acceptor is in limited supply. Think about this, in the absence of oxygen we die; but an organism that can use a different terminal electron acceptor can survive.

A generic example of a simple, 2 complex etc

Figure 1 shows a generic electron transport chain, composed of two integral membrane complexes; Complex I ox and complex II ox . A reduced high energy electron donor, designated HD (such as NADH or FADH 2 ) reduces complex 1 ox giving rise to the oxidized form D (such as NAD or FAD). Simultaneously, a prosthetic group within complex I is now reduced (accepts the electrons) the energy released is used to translocate a proton from one side of the membrane to the other. The net result is that one surface becomes more negatively charged, due to an excess of hydroxyl ions (OH - ) and the other side becomes positively charged due to an increase in protons on the other side. Complex I red can now reduce the prosthetic group in Complex II red while simultaneously oxidizing Complex I red . Electrons pass from Complex I to Complex II via red/ox reactions, regenerating Complex I ox which can repeat the process. Complex II red reduces A, the terminal electron acceptor to regenerate Complex II ox and create the reduced form of the terminal electron acceptor. In this case, Complex II can also translocate a proton during the process. If A is molecular oxygen, water (AH) will be produced. This reaction would then be considered a model of an aerobic ETC. However, if A is nitrate, NO 3 - then Nitrite, NO 2 - is produced (AH) and this would be an example of an anaerobic ETC.

Generic 2 complex electron transport chain. In the figure, DH is the electron donor (donor reduced) and D is the donor oxidized. A is the oxidized terminal electron acceptor and AH is the final product, the reduced form of the acceptor. As DH is oxidized to D, protons are translocated across the membrane, leaving an excess of hydroxyl ions (negatively charged) on one side of the membrane and protons (positively charged) on the other side of the membrane. The same reaction occurs in Complex II as the terminal electron acceptor is reduced to AH.

Based on Figure 2 above and using the electron tower in Figure 1, what is the difference in the electrical potential if (A) DH is NADH and A is O 2 and (B) DH is NADH and A is NO 3 - . Which pairs (A or B) provides the most amount of usable energy?

To be discussed in class

Questions & Answers

do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
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
what is system testing
what is the application of nanotechnology?
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
anybody can imagine what will be happen after 100 years from now in nano tech world
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
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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what does post-translational control refer to?
Teresa Reply
Bioremediation includes
Rachel Reply

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