Photosynthesis

• During the light-dependent reactions of photosynthesis, light energy is absorbed by chlorophyll and converted into chemical energy in the form of ATP and NADPH.
• The sun is the Earth’s main source of energy.
• The producers (autotrophs) such as plants, certain bacteria, and protists, make life on Earth possible.
• Through photosynthesis, light energy from the Sun is converted to chemical energy that different organisms can harness.
• Photosynthesis is a process that harnesses light energy (photons) from the sun to convert CO2 and H2O into Glucose (organic macromolecules).
• Photosynthesis is a reduction-oxidation process: 6CO2 + 6H2O → C6H12O6 + 6O2.
• 1,3 BPGA is reduced by 2 electrons of NADPH which come from the light-dependent reaction, resulting in the formation of PGAL (phosphoglyceraldehyde, also known as glyceraldehyde 3-phosphate).
• When CO2 enters the cycle, it will combine again with the 5-carbon compound RuBP, and the cycle continues.
• PGAL is used in synthesizing glucose and in regenerating RuBP.
• Each 3GPA compound receives an additional phosphate from ATP, which is supplied by the light-dependent reactions, resulting in the formation of 1,3 bisphosphoglycerate (1,3 BPGA).
• A redox reaction is a process which involves the transfer of electrons between atoms.
• There are two types of redox reactions: loss of electron (oxidation) and gain of electron (reduction).
• Oxidation is the loss of electrons from a substance or the gain of oxygen.
• Reduction is the gain of electrons from a substance or the loss of oxygen.
• The leaf is the primary organ of photosynthesis.
• Stomata are tiny pores underside of leaves which facilitate the entry of CO2 and release of O2.
• Chloroplast is a pigment-containing organelle found in plant cells, its pigments absorb sunlight and are mostly concentrated in the mesophyll layer.
• The chloroplast is the organelle where photosynthesis takes place.
• The Calvin cycle, named after its discoverer American biochemist Melvin Calvin, takes place in the stroma and is dependent on the by-products of light-dependent reaction (LDR), ATP and NADPH.
• The process of photosynthesis involves the creation of NADPH, which is used in the light-independent reaction, also known as the Calvin cycle.
• The process of CO2 fixation is facilitated by the enzyme RuBP carboxylase ( RuBisCO ).
• Pigments are stacked up as grana in the thylakoid membrane in the chloroplast.
• The protein channel that facilitates this flow is called the A T P synthase.
• In photosynthesis, A T P molecules are made by adding phosphate to ADP, a process called phosphorylation.
• This results in the buildup of H+ ions inside the thylakoid.
• The Calvin cycle also needs CO2 and produces Glucose.
• In the electron transport chain (ETC), electrons transfer from protein to protein.
• Electrons move on to photosynthesis l.
• The process begins with CO2 fixation wherein carbon dioxide (CO,) is added to the five-carbon compound already found in the stroma called the ribulose phosphate (RuBP) resulting in the production of two molecules of 3-phosphoglycerate (3PGA), which have a total of 6 carbon molecules.
• In photosynthesis, the electrons from water replace those that were excited and left the chlorophyll when light energy was absorbed.
• The energy derived from this process is used to pump H+ ions from the outside to the inside of the thylakoid membrane against the concentration gradient.
• The flow of hydrogens from the inside to the outside of the thylakoid membrane is responsible for the difference in the concentration gradient.
• Light is a form of electromagnetic energy or radiation energy.
• A photon is a particle of light that serves as a discrete bundle of energy.
• Photosystems are the functional units for photosynthesis, characterized by a network of chlorophyll a, accessory pigments such as carotenoids, and associated proteins.
• Photosystems are found in thylakoid membranes and is composed of antennal complex and a reaction center.
• The reaction center of photosystems is composed of transmembrane protein pigment complexes where the photochemical reaction occurs.
• The light-dependent reaction utilizes light, water and other light absorbing molecules, and produces O2, NADPH and ATP.
• Photosystem I has an absorption peak of 700 nm, so its reaction center is called P700.
• The steps that take place from Photosystem II to Photosystem I to complete the light reactions are the following: Chlorophyll a and the accessory pigments absorb energy from sunlight which is transferred to the electrons.