Photosynthesis uses those products from cellular respiration as its reactants and in turn produces glucose and oxygen- the reactants needed for cellular respiration.
Cellular energy metabolism features a series of redox reactions. Heterotrophs oxidize(take electrons from) organic molecules (food) and reduce (give them to) an electron carrier molecule, called NAD+ (in the oxidized form) that accepts electrons from food to become NADH (the reduced form). NADH then cycles back to NAD+ by giving electrons to (reducing) the first complex of the membrane electron transport chain. Thus NAD+/NADH is a key intermediary in shuttling electrons from food molecules to the electrons transport chain for respiration.
The earliest cells, prokaryotes living in an early Earth devoid of free oxygen, used various alternative electron acceptors to carry on anaerobic cellular respiration. After cyanobacteria invented oxygenic photosynthesis and pumped oxygen gas into the oceans and atmosphere, bacteria that adapted their electron transport chains to exploit oxygen as the terminal electron acceptor gained higher energy yield and thus a competitive advantage. One line of aerobic bacteria took up an endosymbiotic relationship within a larger host cell, providing ATP in exchange for organic molecules. The endosymbiont was the evolutionary ancestor of mitochondria. This endosymbiosis must have occurred in the ancestor of all eukaryotes, because all existing eukaryotes have mitochondria (Martin and Mentel, 2010). The evidence for the endosymbiont origin of mitochondria can be found in:
Photosynthesis does much the same thing when converting light energy eventually into glucose in the two phases known as the Light Reactions and the Calvin Cycle.
Energy Transformation: Both Cellular Respiration and Photosynthesis need to transform energy into different forms in order for their reactions to initially take place and continue onward.
and also can use chemiosmosis to generate ATP. , , and synthesize ATP by a process called . These bacteria use the energy of light to create a proton gradient using a . Non-photosynthetic bacteria such as also contain . In fact, mitochondria and s are believed to have been formed when early cells ingested bacteria that could transfer energy using chemiosmosis. This is called the .
Oxidative phosphorylation synthesizes the bulk of a cell’s ATP during cellular respiration. A , in the form of a large proton concentration difference across the membrane, provides the energy for the membrane-localized (a molecular machine) to make ATP from ADP and inorganic phosphate (Pi). The proton gradient is generated by a series of oxidation-reduction reactions carried out by protein complexes that make up an electron transport chain in the membrane. The term oxidative phosphoryation, then, refers to phosphorylation of ADP to ATP coupled to oxidation-reduction reactions.
Photosynthesis Similarities Differences The Relationship Between the Processes Works Cited There are a number of similarities between these two series of reactions such as their equations, transformation of energy, exchange of gases, the Eletron Transport Chain and Chemiosmosis, and the theory of endosymbiosis.
Photosynthesis The equation for photosynthesis is CO2 + H2O +energy = C6H12O6 + O2 Photosynthesis is the process of taking in the sun's energy and converting it into chemical energy to be stored away in the form of glucose.
Metabolism includes catabolism and anabolism. Anabolism is the synthesis of complex molecules from precursors, while catabolism is the breakdown of complex molecules into smaller precursors from which they are synthesized. All these pathways involve biochemical reactions. Free energy describes whether a reaction will occur spontaneously. In metabolism, reactions which are spontaneous are favorable because these run automatically and release free energy. Every reaction has an activation energy which can be lowered down by enzymes. Enzymes do this by bringing the reactants closer together. ATP is the energy currency of all cells. Most of the reactions in the cell require ATP. A non-spontaneous reaction can be coupled to ATP hydrolysis reaction to enable the overall reaction release free energy and therefore become favorable. ATP is generated by cellular respiration, which contains fermentation (anaerobic respiration) and the Krebs cycle (aerobic fermentation).
Cellular respiration is a series of metabolic processes which all living cells use to produce energy in the form of ATP. In cellular respiration, the cell breaks down glucose to produce large amounts of energy in the form of ATP. Cellular respiration can take two paths: aerobic respiration or anaerobic respiration. Aerobic respiration occurs when oxygen is available, whereas anaerobic respiration occurs when oxygen is not available. The two paths of cellular respiration share the glycolysis step. Aerobic respiration has three steps: glycolysis, Krebs cycle, and oxidative phosphorylation. During glycolysis, glucose is broken down into pyruvate and produces 2 ATP. The is also known as TCA cycle which contains a series of Redox reactions to convert pyruvate into CO2 and produce NADH and FADH2. During oxidative phosphorylation, NADH and FADH2 are used as substrate to generate a pH gradient on mitochondria membrane which is used to generate ATP via ATP synthase. Anaerobic respiration contains two steps: glycolysis and fermentation. Fermentation regenerates the reactants needed for glycolysis to run again. Fermentation converts pyruvate into ethanol or lactic acid, and in the process regenerates intermediates for glycolysis.
We have seen how ATP synthase acts like a proton-powered turbine, and uses the energy released from the down-gradient flow of protons to synthesize ATP. The process of pumping protons across the membrane to generate the proton gradient is called . Chemiosmosis is driven by the flow of electrons down the electron transport chain, a series of protein complexes in the membrane that forms an electron bucket brigade. Each of these protein complexes accepts and passes on electrons down the chain, and pumps a proton across the membrane for each electron it passes on. Ultimately, the last complex in the electron transport chain passes the electrons to molecular oxygen (O2) to make water, in the case of aerobic respiration.