Oxidative phosphorylation Oxidative phosphorylation is a metabolic process with the use of enzyme and electron transport system resulting in release of energy in the form of ATP. This process occurs in the mitochondria in eukaryotes and within the plasma membrane in prokaryotes. During this process there is a movement of electron donors to electron acceptors. The way in which oxidative phosphorylation occurs can be explained by the chemiosmotic hypothesis. According to this hypothesis, protons move outward from the mitochondria as a result of electron movement down the chain. The movement of protons away from the mitochondria creates a concentration gradient of protons also known as the chemical potential energy and electrical potential energy, …show more content…
The core process that uses light energy to synthesize energy in the form of ATP is photosynthesis which is also known as a light reaction. Photosynthesis is a process whereby phototrophs mostly autotrophs use carbon dioxide and water in the presence of light energy captured by a pigment called chlorophyll to produce oxygen and starch. Photosynthesis consists of two parts where light energy trapped is used to generate ATP which is then used to reduce carbon dioxide and manufacture cell constituents during dark reactions. Photoheterotrophs are those organisms that can change light energy into energy in the form of ATP, however, cannot fix carbon dioxide from the atmosphere. Three types of phototrophy exists, namely, oxygenic phototrophy, anoxygenic phototrophy, and rhodopsin-based phototrophy. The organisms responsible for oxygenic phototrophy are phototrophic eukaryotes and the cyanobacteria, it is called oxygenic phototrophy because oxygen is generated from the water when light energy from the sun is converted to chemical energy (ATP). The light energy that is captured during this reaction is trapped by a light sensitive pigment called chlorophyll. There are various kinds of chlorophylls such as chlorophyll a and chlorophyll b and each type has its distinctive absorption spectrum for light. Other accessory pigments include phycobilins and carotenoids enable for photosynthesis to occur at broad rangers because of the different absorption spectra. Furthermore, accessory pigments safeguard the microorganism from extreme sunlight which could be detrimental to photosynthesizing organelles. Oxygenic phototrophy consist of two photosystems, namely photosystem I and photosystem II which absorb light energy and longer wavelengths and shorter wavelengths respectively. Oxygenic phototrophy uses non cyclic photophosphorylation and cyclic