Concept explainers
P700* Has the Most Negative Standard Reduction Potential Found in Nature In photosystem I. P700 in its ground state has an
To propose:
In the P700 light reaction, energy efficiency should be determined.
Introduction:
The P700 is also known as primary donor photosystem I which is the chlorophyll that reacts at the center. This molecule associates with the photosystem I and has 700 nm the absorption spectrum.
Explanation of Solution
The equation of quantum light energy is given as,
We have,
Substituting we have,
So hence,
P700 energy capture is calculated by the change of free energy of Gibb that is divided by one 700 nm photon for P700
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Chapter 21 Solutions
Biochemistry
- Melvin Calvin and Andrew Benson determined the steps in the light-independent reactions of photosynthesis by exposing the green alga Chlorella to CO2 labeled with the radioisotope carbon 14. By looking at which compounds the C14 ended up in, they were able to identify all intermediates in this cyclic pathway. Why did they predict correctly that the same set of intermediates would be formed in the light reaction in land plants?arrow_forwardIn cyclic photophosphorylation, it is estimated that two electrons must be passed through the cycle to pump enough protons to generate one ATP. Assuming that the AG for hydrolysis of ATP under conditions existing in the chloroplast is about –50 kJ/mol, what is the corresponding percent ef- ficiency of cyclic photophosphorylation, using light of 700 nm?arrow_forwardWhat is implied about the energyrequirements of photosystems I and II by the fact that there is a difference in the minimum wavelength of light needed for them tooperate (700 nm for photosystem I and 680 nm for photosystem II)?arrow_forward
- What fraction of the energy of 700-nm light absorbed by photosystem I is trapped as high-energy electrons?arrow_forwardIn cyclic photophosphorylation, it is estimated that two electrons must be passed through the cycle to pump enough protons to gener- ate one ATP. Assuming that the AG for hydrolysis of ATP under con- ditions existing in the chloroplast is about –50 kJ/mol, what is the corresponding percent efficiency of cyclic photophosphorylation, using light of 700 nm?arrow_forwardIn cyclic photophosphorylation, it is estimated that two electrons must be passed through the cycle to pump enough protons to generate one ATP. Assuming that the ΔG for hydrolysis of ATP under conditions existing in the chloroplast is about -50 kJ/mol, what is the corresponding percent efficiency of cyclic photophosphorylation, using light of 700 nm?arrow_forward
- Calculate (in kJ/mol) the energy that is required by the Rhodopseudomonas viridis photophosphorylation system to synthesize 3 ATP? (Assume that the R. viridis F1F-ATP synthase c-subunit rotor contains 12 c-subunits and that the R. viridis cytochrome b/c complex translocates 2 H/e". Also assume that the wavelength of lig! is 680 nm.) Number of photons required to synthesize 3 ATP = photons Energy = kJ/molarrow_forwardPhotosynthetic response curve to light for sun (solid line, N = 14) and shade leaves (dashed line, N = 21) of S. Why in this graph do we see shaded leaves have lower values compared to light leaves as PAR is increasing?arrow_forwardWhat is midpoint potential of redox active centers in photosynthetic organisms? What factors affect this? Also how does charge become offset during water oxidation rxns?.arrow_forward
- If plants described in problem 4 are illuminated by a combination of light of 680 nm and 700 nm, the oxygen production exceeds that of either wavelength alone. Explain.arrow_forwardavelengths (Choose J |Choose | graph plotting a pigment's light absorption versus wavelength reaction- center complex is system consists of a reaction-center complex surrounded by nt-harvesting complexes absorption spectrum spectrophotometer molecule located in the reaction center accepts excited ctrons photosystem light harvesting complex reaction-center chlorophyll a of this photosystem iş called P680 ause it is best at absorbing a wavelength of 680 nm. primary electron acceptor wavelength PSI estion 4 PS II action spectrum >arrow_forwardFor the chloroplast, the thylakoid membrane separates the thylakoid lumen from the stroma; the protons from the photosystems are transported, like with the mitochondrial inner membrane, against the gradient from the lumen to the stroma. However, the pH(lumen) – pH (stroma) is much larger, about 3.4. Calculate delta psi (the electric potential) for the thylakoid membrane, given that ∆G of proton transport is about the same as for the mitochondrion. Then comment on its permeability to ions, compared to the mitochondrial inner membrane’s permeability to ions.arrow_forward
- BiochemistryBiochemistryISBN:9781305577206Author:Reginald H. Garrett, Charles M. GrishamPublisher:Cengage Learning