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
62- ) 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
A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
