Search results
Results from the WOW.Com Content Network
This transport chain produces a proton-motive force, pumping H + ions across the membrane and producing a concentration gradient that can be used to power ATP synthase during chemiosmosis. This pathway is known as cyclic photophosphorylation, and it produces neither O 2 nor NADPH.
Cyclic phosphorylation is important to create ATP and maintain NADPH in the right proportion for the light-independent reactions. The net-reaction of all light-dependent reactions in oxygenic photosynthesis is: 2 H 2 O + 2 NADP + + 3ADP + 3P i → O 2 + 2 H + + 2NADPH + 3ATP. PSI and PSII are light-harvesting complexes.
An important example is the formation of adenosine triphosphate (ATP) by the movement of hydrogen ions (H +) across a membrane during cellular respiration or photosynthesis. An ion gradient has potential energy and can be used to power chemical reactions when the ions pass through a channel (red).
An electrochemical gradient is a gradient of electrochemical potential, usually for an ion that can move across a membrane. The gradient consists of two parts: The chemical gradient, or difference in solute concentration across a membrane. The electrical gradient, or difference in charge across a membrane.
The PMF is the sum of a proton chemical potential (given by the proton concentration gradient) and a transmembrane electrical potential (given by charge separation across the membrane). Compared to the inner membranes of mitochondria, which have a significantly higher membrane potential due to charge separation, thylakoid membranes lack a ...
Photosynthesis usually refers to oxygenic photosynthesis, a process that produces oxygen. Photosynthetic organisms store the chemical energy so produced within intracellular organic compounds (compounds containing carbon) like sugars, glycogen , cellulose and starches .
In contrast, C3 plants directly perform the Calvin Cycle in mesophyll cells, without making use of a CO 2 concentration method. Malate, the four-carbon compound is the namesake of "C4" photosynthesis. This pathway allows C4 photosynthesis to efficiently shuttle CO 2 to the RuBisCO enzyme and maintain high concentrations of CO 2 within bundle ...
According to the hypothesis, the high concentration of organic substances, particularly sugar, inside the phloem at a source such as a leaf creates a diffusion gradient (osmotic gradient) that draws water into the cells from the adjacent xylem. This creates turgor pressure, also called hydrostatic pressure, in the phloem. The hypothesis states ...