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By the end of this section, you will be able to:
  • Describe how electrons move through the electron transport chain and what happens to their energy levels
  • Explain how a proton (H + ) gradient is established and maintained by the electron transport chain

In the last module we discussed the various ways cells synthesize ATP and had a detailed discussion on substrate level phosphorylation. The second primary mechanism for ATP and energy formation is by oxidative phosphorylation. First and foremost, oxidative phosphorylation does not imply the use of oxygen, it can, but it does not have to use oxygen. It is called oxidative phosphorylation because it relies on red/ox reactions to generate a membrane potential that can then be used to do work. One of the "machines" that can be driven by the membrane potential, also referred to as the proton motive force or PMF , is the F 1 F 0 ATPase . Unlike SLP, which directly synthesizes ATP, Oxidative Phosphorylation is an indirect mechanism. It is derived from a process that begins with moving electrons through a series of electron transporters or carriers that undergo red/ox reactions. The energy released from these reactions leads to the movement of protons across a membrane. This accumulation of protons on ones side of the membrane "polarizes" or "charges" the membrane, with a net positive (protons) on one side of the membrane and a negative charge on the other side of the membrane. this is called an electrical potential due to the charge separation. In addition, the accumulation of protons also causes a pH gradient to form across the membrane and is referred to as the chemical potential . Together this is called an electro-chemical gradient across the membrane. Think of this as a cellular capacitor, as the charge and pH gradient grows more and more energy is stored and can be used to do work, such as driving the F 1 F 0 ATPase and generating ATP indirectly.

Below the basic concepts of oxidative phosphorylation are described. Remember for ATP synthesis to occur two criteria must be met, the first is the formation of the membrane potential via a series of red/ox reactions, referred to as an electron transport chain and second, a membrane bound, proton driven F 1 F 0 ATPase, that uses the potential energy from the PMF to drive the formation of ATP by allowing protons to move from the higher concentration on one side of the membrane to the other side of lower concentration. Nowhere is molecular oxygen required for this to happen. Oxygen is a terrific terminal electron acceptor and allows for a very efficient way to generate a large PMF, however, other compounds such as hydrogen sulfide can also act as terminal electron acceptors. The eukaryotic mitochondrion has evolved an incredibly efficient electron transport chain to maximize ATP production for every 2 high energy electrons that enter the chain. While this mitochondrial electron transport chain is what we (eukaryotes) use, the diversity of the electron transport chain in nature is one of the most amazing features of life on this planet. Think about all of the unique and inhospitable places there are on this planet, yet some form of life can survive there. It makes one think about the possibility of life on other worlds. Remember all that is required is a donor of high energy electrons, carriers to move the electrons by red/ox reactions in a membrane, and a terminal electron acceptor. As we will discuss below, as long as the terminal electron acceptor has a higher affinity for the electrons than the electron donor, the electrons will move, and the energy can be captured by the cell.

Questions & Answers

what is math number
Tric Reply
x-2y+3z=-3 2x-y+z=7 -x+3y-z=6
Sidiki Reply
Need help solving this problem (2/7)^-2
Simone Reply
x+2y-z=7
Sidiki
what is the coefficient of -4×
Mehri Reply
-1
Shedrak
the operation * is x * y =x + y/ 1+(x × y) show if the operation is commutative if x × y is not equal to -1
Alfred Reply
An investment account was opened with an initial deposit of $9,600 and earns 7.4% interest, compounded continuously. How much will the account be worth after 15 years?
Kala Reply
lim x to infinity e^1-e^-1/log(1+x)
given eccentricity and a point find the equiation
Moses Reply
12, 17, 22.... 25th term
Alexandra Reply
12, 17, 22.... 25th term
Akash
College algebra is really hard?
Shirleen Reply
Absolutely, for me. My problems with math started in First grade...involving a nun Sister Anastasia, bad vision, talking & getting expelled from Catholic school. When it comes to math I just can't focus and all I can hear is our family silverware banging and clanging on the pink Formica table.
Carole
I'm 13 and I understand it great
AJ
I am 1 year old but I can do it! 1+1=2 proof very hard for me though.
Atone
hi
Adu
Not really they are just easy concepts which can be understood if you have great basics. I am 14 I understood them easily.
Vedant
find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
I know this work
salma
The given of f(x=x-2. then what is the value of this f(3) 5f(x+1)
virgelyn Reply
hmm well what is the answer
Abhi
If f(x) = x-2 then, f(3) when 5f(x+1) 5((3-2)+1) 5(1+1) 5(2) 10
Augustine
how do they get the third part x = (32)5/4
kinnecy Reply
make 5/4 into a mixed number, make that a decimal, and then multiply 32 by the decimal 5/4 turns out to be
AJ
how
Sheref
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
ninjadapaul
20/(×-6^2)
Salomon
okay, so you have 6 raised to the power of 2. what is that part of your answer
ninjadapaul
I don't understand what the A with approx sign and the boxed x mean
ninjadapaul
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
Salomon
I'm not sure why it wrote it the other way
Salomon
I got X =-6
Salomon
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
ninjadapaul
oops. ignore that.
ninjadapaul
so you not have an equal sign anywhere in the original equation?
ninjadapaul
hmm
Abhi
is it a question of log
Abhi
🤔.
Abhi
I rally confuse this number And equations too I need exactly help
salma
But this is not salma it's Faiza live in lousvile Ky I garbage this so I am going collage with JCTC that the of the collage thank you my friends
salma
Commplementary angles
Idrissa Reply
hello
Sherica
im all ears I need to learn
Sherica
right! what he said ⤴⤴⤴
Tamia
hii
Uday
hi
salma
hi
Ayuba
Hello
opoku
hi
Ali
greetings from Iran
Ali
salut. from Algeria
Bach
hi
Nharnhar
A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
Kimberly Reply
Jeannette has $5 and $10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
August Reply
What is the expressiin for seven less than four times the number of nickels
Leonardo Reply
How do i figure this problem out.
how do you translate this in Algebraic Expressions
linda Reply
why surface tension is zero at critical temperature
Shanjida
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
s.
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 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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