Please answer all questions: What would be the free energy for proton movement f
ID: 87854 • Letter: P
Question
Please answer all questions:
What would be the free energy for proton movement from the intermembrane space to the matrix in a mitochondria under the following sets of conditions (plz answer in kcal/mole, and assume room temperature of 25° C). All voltages are oriented with the higher concentration of +ve ions in the intermembrane space, so the matrix is more negative; make sure the signs on your voltages and your free energies are correct.
1) pH in intermembrane space is 4, pH in matrix is 7, voltage across inner mitochondrial membrane is 50 mV
2) pH in intermembrane space is 6, pH in matrix is 8, voltage across inner mitochondrial membrane is 100 mV
3) pH in intermembrane space is 6, pH in matrix is 7, voltage across inner mitochondrial membrane is 10 mV
4) pH in intermembrane space is 4, pH in matrix is 6, voltage across inner mitochondrial membrane is 75 mV
5-8) How many protons would have to be transported across the membrane in order to generate one ATP (assuming energy to generate an ATP is 12 kcal/mole) in each of the above cases?
9) A famous plant scientist determined characteristics of mitochondria in a particular species of petunia. She determined that the voltage across the inner mitochondrial membrane was 40 mV (more positive ions inside the inner membrane space), and that exactly 2 protons were required to be transported through the F1/Fo ATPase to produce one ATP. If the energy to generate an ATP is 12 kcal/mole, what was the approximate pH difference between the inner membrane space and the matrix?
Explanation / Answer
ANSWER:
4) pH in intermembrane space is 6, pH in matrix is 8, voltage across inner mitochondrial membrane is 100 mV
5-8) Two protons are pumped per electron in the cytochrome b-c1 complex, however, and there is good evidence for a so-called Q-cycle, in which ubiquinone is recycled through the complex in an ordered way that makes this two-for-one transfer possible. Exactly how this occurs can now be worked out at the atomic level, because the complete structure of the cytochrome b-c1 complex has been determined by x-ray crystallography
9) Incubation of Petunia hybrida cells with H2O2 leads to an increase in alternative oxidase activity measured after 24 h. This increased activity is accompanied by an increase in alternative oxidase protein. A model is presented for the regulation of alternative oxidase protein synthesis in which active oxygen species and especially H2O2 play a crucial role as second messengers in the signal transducing pathway from the mitochondria to the nucleus. It is proposed that also the induction of the alternative oxidase by salicylic acid is mediated via H2O2.