To review:
Definition of the following terminologies:
(a) Photosynthesis
(b) Photosystem
(c) Reaction center
(d) PS I
(e) PS II
Introduction:
Oxygenic photosynthesis is the process through which plants convert inorganic substances into food, using sunlight. It involves the absorption of sunlight by chlorophyll and using it to convert inorganic substances into food energy. The process of photosynthesis takes place in several steps and stages, involving various parts of the cell and thylakoid.
Explanation of Solution
a) Photosynthesis: Photosynthesis is a light-driven biochemical reaction where CO2 (carbon dioxide) and water (H2O) are converted into organic molecules like glucose, with the help of chlorophyll and energy from sunlight, which is used by the plant as a food source.
b) Photosystem: Photosystems are biochemical mechanisms like membrane-bound protein complexes found in chloroplasts or the cell membrane of photosynthetic bacteria that perform photosynthesis. They are involved in the transfer of energy and electrons.
c) Reaction center: Reaction center is the functional component of a photosystem that uses the captured light energy (of a certain wavelength) to drive trans-membrane electron transport. It consists of proteins complexes and certain pigments (chlorophyll) that absorb light.
d) PSI: PSI (photosystem-I) is one of the two photosystems present in the membrane of thylakoid of chloroplast and is composed of protein complexes and forms an integral part of the membrane, it uses light-driven transport to synthesize ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate reduced).
e) PSII: PSII is the first component of a photosystem that is a large membrane-spanning protein–pigment complex, which oxidizes water molecules to release an electron and donates energized electrons (excited by sunlight) to electron carriers.
Hence, photosynthesis is a process comprising of different processes and systems like PSI and PSII and certain pigments like chlorophyll, forming the reaction center.
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Chapter 13 Solutions
Biochemistry: The Molecular Basis of Life
- Identify the chemical basis for ApH and AY across the chloroplast thylakoid membrane by dragging the descriptions to their targets. Be sure to notice that the upper arrow iindicates ApH and the lower arrow indicates ΔΨ. ATP synthase complex H+ N ADP + P₁ Light energy ATP H*N Photosystem I/II- Chloroplast N side Aus PN ApH T + Thylakoid membrane HTp H+p Lumen Stroma P side Proton circuit A B High H concentration Low positive charge High positive charge Low H+ concentration Within the image, identify the types of proton translocation by dragging each label to its target. O XH₂ 2H+ + Z 2 H* ZH₂ O XH₂ Z 2H+ ZH₂ 2H+ C A B Proton pump Redox looparrow_forwardIn chloroplasts, the light reactions power the creation of ATP via chemiosmosis. In relation to this process, which of the following is true? a) ATP synthase breaks ATP down into ADP, creating energy to fuel chemiosmosis. b) Oxygen is used as a source of electrons to replace those lost in photosystem II. c) Chemiosmosis during the light reactions is also used in the reduction of NADPH and FADH2. d) As excited electrons fall back down to a lower energy state, they create a proton gradient that is used to fuel the phosphorylation of ADP.arrow_forwardThylakoids were isolated from chloroplasts and incubated in the dark in an acidic solution (pH 4) to equilibrate the pH. After 30 minutes, the thylakoids were transferred to a basic solution (pH 8) and kept in the dark. Will this system produce ATP? Explain. Will this system produce G3P? Explain.arrow_forward
- 1. A) For the schematic of a chloroplast shown in the image attached, match the major input and output molecules of photosynthesis to the letters shown. Molecules: CO2, H2O, O2, sugar A: B: C: D: B) In the image attached, the light reactions are shown to take place in the thylakoid. Where specifically do these reactions take place? C) Where does the Calvin cycle take place?arrow_forwardExplain, using a diagram, how during acyclic photophosphorylation (photophase) an electrochemical gradient is produced within reservoirs in the grana of chloroplasts. What is the result?arrow_forwardThe photosynthetic process, used by the chloroplasts of green plants and green algae, is best represented by which of the following balanced equations? C6H12O6 + 6O2 + 6H2O g 6CO2 + 12H2O C6H12O6 + C6H12O6 g C12H22O11 + H2O 6CO2 + 12H2O g C6H12O6 + 6O2 + 6H2O C12H22O11 + H2O g C6H12O6 + C6H12O6 6CO2 + 12H2S g C6H12O6 + 6S2 + 6H2Oarrow_forward
- Daniel Arnon and coworkers carried out experiments with intact, salt- washed chloroplasts to study photophosphorylation. When the chloroplasts were illuminated in the presence of ADP +P, ATP was produced, but oxygen was not produced or nor consumed. ATP formation was not accom- panied by a measurable electron transport involving any external electron donor or acceptor. The overall reaction for this result is: ADP + P -", ATP When NADP+ was included in addition to the ADP + P, ilumination of the intact chloroplats again resulted in resulted in the photophosphorylation of ADP to ATP. In addition, the NADPpt was reduced to NADPH + H* and o, was produced. Moreover, the light-induced reduction of NADP* was greatly decreased if ADP + P; were ommitted. The equation for this reaction is: NADP* + H,0 + ADP + R -", NADPH + H + ATP + }02 Briefly describe the mechanism(s) of these two types of photophosphoryla- tion that explain all of these results.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_forwardIn 150 word count with reference answer the below question The equation for photosynthesis is 6CO2 + 6H2O + Sunlight --> C6H12O6 + 6O2. Explain the role of each of the products (left side of the arrow) and explain where the products (right side of the arrow) came from.arrow_forward
- Explain, using a simple diagram, the relationship between acyclic photophosphorylation (photophase) and the Calvin cycle (dark phase).arrow_forwardH218O is added to a suspension of chloroplasts capable of photosynthesis.Where does the label appear when the suspension is exposed to sunlight?arrow_forwardEukaryotic chloroplasts generate exactly how many product molecules, in their consumption of six substrate carbon dioxide molecules and twelve water molecules, during oxygenic photosynthesis? twelve C6H12O6 molecules, six H2O molecules, and three CO2 molecules are produced one C6H12O6 molecule, six H2O molecules, and six O2 molecules are produced six C6H12O6 molecules, three H2O molecules, and six CO2 molecules are produced twelve H2O molecules and six O2 molecules are produced six H2O molecules and twelve CO2 molecules are producedarrow_forward