Respiration And Photosynthesis Cycle

Published Date: 02 Nov 2017

Emma Barnes

Biology

Respiration and Photosynthesis Cycle

According to the syllabus and instructors post, Week 3 assignment is to describe the stages of cellular respiration and photosynthesis and their interaction and interdependence including raw materials, products, and amount of ATP or glucose produced during each phase. This links to specific organelles within the eukaryotic cell and explain not only the importance but also significance of these processes and their cyclic interaction to the evolution and diversity of life.

Cellular respiration and photosynthesis are the two chief processes carry out by most living organisms to attain functional energy from nature. Whereas photosynthesis is performed by most plants that can make their own food, most animals achieve their energy necessities through cellular respiration. Light-dependent Reactions and Light-independent Reactions or Calvin Cycle are the stages of chemical reactions during the process of photosynthesis.

During the light reaction solar energy is transformed into chemical energy. The second stage is when synthesis (Calvin Cycle) uses the energy from the light reaction and change CO2 taken from the atmosphere into sugar. The Calvin cycle uses ATP and NADPH to transform three molecules of CO2 to one molecule of a 3-carbon sugar. The plant can then use this small sugar to make larger sugars such as glucose and many other organic compounds. The main role of the light reactions is to replenish the stroma with the ATP and NADPH (an electron acceptor, providing reducing power) necessary for the Calvin cycle. During this process, O2 is released as a by-product and water is split. Furthermore, during the process of photophosphorylation, light reaction produces ATP by means of chemiosmosis. Chemical energy is converted by the initiation of light energy, forming two compounds; ATP and NADPH.

According to Simon, Reece, & Dickey (2013), Melvin Calvin who, along with his colleagues, toiled with many steps in the 1940s, thus the Calvin cycle was named. The beginning of the cycle started with the amalgamation of CO2 into organic molecules. This process; carbon fixation involves the reduction including electrons delivered by NADPH.

Since "ATP from the light reactions influences parts of the Calvin cycle, it is the Calvin cycle that creates sugar, with the aid of ATP and NADPH from the light reaction" (The Calvin cycle The Nonlight Requiring Reaction, 2013) . The metabolic phases of the Calvin cycle are at times referred to as the light-independent reactions, since none of the steps needs light directly.

The raw materials for anabolic pathways and fuel for respiration is provided when Carbohydrates takes form of disaccharide sucrose travel through the veins to non-photosynthetic cells (Simon, Reece, & Dickey, 2013), and formation of the extracellular polysaccharide cellulose. Cellulose is the utmost plentiful organic molecule and perhaps the planet, as well as the main ingredient of cell walls in plants.

What makes photosynthesis important is when energy entering the chloroplasts as sunlight becomes warehoused as the chemical energy inside carbon-based combinations. That sugar produced in the chloroplasts provides plants with chemical energy and carbon frameworks to make all the major organic molecules of cells. Photosynthesis manufactures over 500 billion metric tons of carbohydrates and is the utmost important method on earth. It is also responsible and responsible for the occurrence of oxygen in our atmosphere.

Cellular respiration is the process which the chemical energy of "food" molecules is released and partly taken in the method of ATP (BioCoach Activity, 2013).  Glucose which is sugar is needed to energize this process and it is either aerobic (oxygen is existing) or anaerobic (oxygen is lacking). During the week’s studies, we learned that "aerobic cellular respiration usually happens in eukaryotic cells and the processes involved take place in small structures inside the cell known as mitochondria" (Simon, Reece, & Dickey, 2013). This type of respiration allows the making of a method of biochemical energy called adenosine triphosphate (ATP).

Glycolysis which is the original step starts in the cell cytoplasm; a gel substance filled in cells which organelle’s are located, outside of the mitochondrion and before the aerobic cellular respiration can occur. Existing cells attain products of sugar molecules and undertake cellular respiration in order to create ATP molecules. Several use oxygen and others do not. These processes involve a set of chemical reactions to transform

There are two stages involved during the breaking down process of glucose molecules; aerobic respiration and glycolysis. Approximately half of organic materials are used up as energy for cellular respiration in plant mitochondria. According to Simon, Reece, & Dickey (2013), "Cellular respiration begins at the stage of glycolysis in the cytoplasm of the cells, and produces 2 carbon-based molecules called pyruvate, and 2 molecules of ATP" (Simon, Reece, & Dickey, 2013). During this stage, there is no involvement of oxygen.

Glycolysis requires an initial investment of 2 molecules of ATP. This called phosphorylation. Adding the terminal phosphates of 2 ATP molecules destabilizes glucose and makes available energy locked up in its bonds.

Two analogies that come to mind here are lighting a candle before it can give off heat and light; or kick starting a gasoline powered motorcycle. Lysis is the next step. The phosphorylated six-carbon sugar is split by enzymes into two three carbon molecules of PGAL. Each PGAL is then simultaneously oxidized to PGA.

Oxidation in this case is removal of hydrogen. A hydrogen ion is removed and added to the ion carrier NAD+ to form two molecules of NADH. Enough energy is released here to generate an ATP from each PGAL oxidation. Lastly each PGA is converted to pyruvic acid. This involves dephosphorylating. Each PGA donates its phosphate to an ADP to generate usable ATP. The net energy gain is 2 ATP. A total of 4 ATP are generated but 2 ATP were endowed in the beginning.

The Aerobic Respiration process takes place in specific configurations inside the mitochondria, and use the products of glycolysis to discharge energy, along with CO2 and water as the secondary result of the reaction. This free energy is kept in the method of ATP molecules. Typically, a total of 38 ATP molecules are created.

The link reaction is the first stage of aerobic respiration. This occurs in mitochondria in eukaryotes. The link reaction is relay between glycolysis and a series of reactions entailing a high yield of ATP called the Krebs cycle. The link reaction begins with the decarboxylation of pyruvate. A molecule of CO2 is removed. The product formed is a two-carbon acetyl group which reacts with coenzyme A (It is worth mentioning that this is a derivative of Vitamin B5, cysteine and ATP.) to form Acetyl Co-A.

The decarboxylation process also involves oxidation. A hydrogen ion is removed, as in glycolysis, to form NADH/H+. In lipid metabolism the oxidation of the fatty acid chains also results in the formation of two carbon atom (acetyl) fragments which then pass through the Krebs cycle. A fatty acid chain can produce multiple 2C acetyl groups. This is why fats can yield double the amount of energy as carbohydrates or proteins. Amino acids are first de-animated, and then enter the Krebs cycle according to their various radicals.

In raw input for the Krebs cycle is the 2 carbon Acetyl group. The carbon balance is restored because at two stages in the cycle a molecule of CO2 is released. As in glycolysis oxidation is a key feature. During several steps along the way hydrogen ions are removed. the transport of hydrogen by carrier molecules is the key to producing high yields of ATP. At the start of the Krebs cycle the 2C acetyl group joins the 4C molecule remaining at the end of the cycle to make 6C citric acid.

There are two turns of the Krebs cycle for each 6C glucose input. Furthermore, when computing the possible net ATP yield, two link reactions and a Glycolysis must considered. There is a probable yield of 38 molecules of ATP from the breakdown of one glucose molecule in aerobic respiration. Simply put, glucose is a large stable molecule with lots of chemical energy trapped in its bonds. It is easy to release this energy explosively, say, by combustion; but that would damage the cell, and most of the energy would be lost as useless heat. The complex biochemistry of cell respiration has evolved to obtain in a series of enzyme-controlled, gentle, incremental steps as much chemical energy as possible to make ATP (from ADP and P).

Probable energy to make ATP is made possible by the electron transport chain. The chain consists of a short series of coenzyme carriers, embedded in tandem in the crista of mitochondria that begins with NAD+ and ending in O2. It is only at this extreme terminus of the complex biochemistry that the oxygen that we breathe in is utilized.

Each time excited electrons are removed from their associated protons and passed down the chain enough potential energy is extracted to yield 3 ATP molecules. In the case of FAD, the second carrier in the chain and at a slightly lower energy level and a little more electronegative than NAD+, only 2 ATP are produced.

Chemiosmosis explains precisely how ATP is produced from the electron transport chain. The enzymes controlling the steps in the chain, embedded in the crista membrane, are actually proton pumps. They use the energy from the passage of excited electrons to change their shape and pump disembodied H+ from the matrix of the mitochondria which contains all the Krebs cycle machinery into the inter-membrane space. Protons accumulate here and the pH is detectably lower than in the matrix.

The accumulation of protons in the inter-membrane space creates a significant concentration gradient. The electron carrier molecules and their associated protein-pumping enzymes are coupled with ATP synthase in the inner membranes of mitochondrial crista. ATP synthase harnesses the concentration gradient of the protons. As protons speed from a high to a low concentration, through the open channels of ATP synthase, their energy is harnessed to make ATP from ADP and P. Only at this point do the generic protons rejoin generic electrons, previously transported by the chain, to form respiratory H2O with oxygen, the ultimate and most electronegative of the carriers.

Cristae are the internal compartments formed by the inner membrane of a mitochondrion. They are studded with proteins, including ATP synthase and a variety of cytochromes. The maximum surface for chemical reactions to occur is within the mitochondria. This allows cellular respiration (aerobic respiration since the mitochondria requires oxygen) to occur.

The cristae greatly increase the surface area on which the above mentioned reactions take place. If they were absent, the inner membrane would be reduced to a single spherical shape, and with less reaction surface available, the reaction efficiency would be likewise reduced. Therefore, cristae are a necessity for the mitochondria to function efficiently Photosynthesis and respiration are basically the same, but occurs in reverse. In the simplest term, they complement each other throughout the environs. In photosynthesis, carbon dioxide and water yield glucose and oxygen. Thus, glucose and oxygen yield carbon dioxide and water through the respiration process.

Photosynthesis is the single important solar energy storage method on Earth and is not only the basis of all of our food, but also the utmost human’s energy assets. There is indication that photosynthesis is an olden process that devised not long after the origin of life and has changed by way of a multifaceted path to create the delivery of types of photosynthetic organisms and metabolisms found today (Blankenship, 2002; 

Humans depend on plants to acquire oxygen, plants produce glucose (sugar) that aids in living and growing, as well as we giving off carbon dioxide. hence, plants need healthy energy to create glucose to create oxygen which human’s depend on to live, basically, without photosynthesis, mankind would not be existent,

Over 3 billion years ago, the development of photosynthesis occurred in bacterial. While the molecular oxygen (O2) arose in the air, organisms that could use O2 for respiration initiated their evolution, and "aerobic" respiration come to be a prevailing method of metabolism amongst bacteria and certain archaea. Eukaryotic cells developed somewhere amid one and two billion years ago. Eukaryotic cells appear to have ascended from prokaryotic cells, especially out of the Archaea.

Certainly, there are numerous comparisons in molecular biology of modern archaea and eukaryotes. Nonetheless, the origin of the eukaryotic organelles, specifically chloroplasts and mitochondria, is clarified by evolutionary relations amongst original nucleated cells and certain respiratory and photosynthetic bacteria, which led to the growth of these organelles and the related detonation of eukaryotic multiplicities.