I can count the carbons, the waters on the reactant side, the oxygens, and the glucose, but I cannot seem to locate where in either light or dark reaction 6 water molecules were produced again. Where and when were they produced?
Some of the water that's split is regenerated when the hydroxyl radicals (reactive oxygen species) are converted to hydrogen peroxide, water, etc. by superoxide dismutases and antioxidative mechanisms in the chloroplast (peroxisomes/catalases, etc. take care of this). There's also some evidence that the presence of mannitol, ascorbate and glutathione protect against ROS produced in chloroplasts as well. So you input water, and in an effort to avoid oxidative damage, you do get some water generated. However, the balanced equation doesn't reflect this because it's not an actual product of photosynthesis.
Respiration consists of a complicated series of chemical reactions. In the first stage, glucose is oxidized, and the chemical potential energy of its bonds is transferred to the chemical potential bonds of an ATP molecule. The ATP molecule can then be transported throughout the cell where its stored energy is used to complete various tasks within the cell. This process releases carbon dioxide gas and water.
The ATP and NADPH produced in the light reactions are used to incorporate carbon dioxide into a 3-carbon sugar.
Light + Chlorophyll = Electrons!
When photons of light interact with chlorophyll, electrons in the Magnesium atom become excited.
This happens with ~1 % of all sunlight that strikes the surface of the earth.
Isolated chlorophyll will
when exposed to light, as the excited electrons return to the ground state.
Complexes of protein and pigment molecules that are embedded in the thylakoid membrane.
A sequence of chemical reactions transfers the sun’s light energy into the chemical bonds that hold together special, energy-carrying molecules (the most common of which are called ).
Aluminum went from Al0 on the left to Al3+ on the right. Each aluminum atom lost three electrons.
Oxygen stayed the same on both sides.
With this information, we can tell which atom was oxidized and which atom was reduced. There are two mnemonics to remember which reaction is oxidation and which reaction is reductions.
This process is called photosynthesis. Temperature, carbon dioxide concentration and light intensity are factors that can limit the rate of photosynthesis.
Plants absorb water through their roots, and carbon dioxide through their leaves. Some glucose is used for respiration, while some is converted into insoluble for storage. The stored starch can later be turned back into glucose and used in respiration. Oxygen is released as a by-product of photosynthesis.
Environmental scientists recognize that the fundamental source of energy for most life on earth is the sun. Through photosynthesis, plants capture the light and convert it into chemical potential energy. Plants then store the potential energy in the form of (biological matter that fuels nearly every animal on earth).
Identify the atoms that were oxidized and which atoms were reduced in the following reaction:
Fe2O3 + 2 Al → Al2O3 + 2 Fe
The first step is to assign oxidation numbers to each atom in the reaction.
Direct incoming photons into the "
" where chlorophyll a molecules produce excited electrons which are transferred to an
electron transport chain
: central chlorophyll works best at a light wavelength of 680 nm (
In respiration energy is released fromsugars when electrons associated with hydrogen are transported to oxygen (theelectron acceptor), and water is formed as a byproduct. The mitochondriause the energy released in this oxidation in order to synthesize ATP. Inphotosynthesis, the electron flow is reversed, the water is split (not formed),and the electrons are transferred from the water to CO2 and in theprocess the energy is used to reduce the CO2 into sugar. Inrespiration the energy yield is 686 kcal per mole of glucose oxidized to CO2,while photosynthesis requires 686 kcal of energy to boost the electrons from thewater to their high-energy perches in the reduced sugar -- light provides thisenergy.
In photosynthetic cells, a large amount of hydrogen peroxide is produced in peroxisomes through photorespiration, which is a metabolic pathway related to photosynthesis. Hydrogen peroxide, a reactive oxygen species, oxidizes peroxisomal proteins and membrane lipids, resulting in a decrease in peroxisomal quality. We demonstrate that the autophagic system is responsible for the elimination of oxidized peroxisomes in plant. We isolated Arabidopsis mutants that accumulated oxidized peroxisomes, which formed large aggregates. We revealed that these mutants were defective in autophagy-related (ATG) genes and that the aggregated peroxisomes were selectively targeted by the autophagic machinery. These findings suggest that autophagy plays an important role in the quality control of peroxisomes by the selective degradation of oxidized peroxisomes. In addition, the results suggest that autophagy is also responsible for the functional transition of glyoxysomes to leaf peroxisomes.
In oxidation-reduction or redox reactions, it is important to be able to identify which atoms are being oxidized and which atoms are being reduced. To identify if an atom is either oxidized or reduced, you only have to follow the electrons in the reaction.