Define the following terms: a. light-dependent reactions b. Z-scheme c. water-oxidizing clock d. noncyclic electron transport e. cyclic electron transport
Define the following terms:
a. light-dependent reactions
b. Z-scheme
c. water-oxidizing clock
d. noncyclic electron transport
e. cyclic electron transport
Photosynthesis is a process by which green plants and some microbes use light energy to make glucose (chemical energy). Chlorophyll is the pigment that gives the plant green color and is responsible for absorbing light energy.
a. Light-dependent reactions: This is the part of photosynthesis that needs light to make two materials for the next step of photosynthesis. It takes place in the thylakoid membranes. The light-dependant reactions make ATP for energy and NADPH, that act as the reduced electron carrier.
b. Z-scheme: During the light reaction described above, a series of oxidation-reduction reactions occur. In this scheme, electrons from water molecules are donated o P680. P680 then absorbs light to get excited to P680*. The excited P680* donates an electron to the downstream quinone-cytochrome system, then to PS1, converting P700 to an excited state. The electron is eventually transferred to NADP to form NADPH.
c. Water-oxidizing clock: It is also called a water-evolving complex. This consisted of a water-oxidizing enzyme that carries our photooxidation of water in photosynthesis. This complex stabilizes the intermediates of water splitting reaction such that electrons can be transferred one after another.
d.Noncyclic electron transport: It is a type of electron transport where the electron does not return to its starting material. In this, the electron is removed from the water, travels through PS 2, then PS1 to finally form NADPH. Ths electron transfer needs light absorption twice, once at each photosystem, and it produces ATP.
e.Cyclic electron transport: In this, the electron travels cyclically. It has two primary function-firstly to produce ATP and balance of the ATP/NADPH ratio, and second to protect the photosystems from inhibition from light.
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