query: which process produces the most atp molecules in aerobic cellular respiration

pos: Cellular respiration third phosphate group is added to form ATP (adenosine triphosphate), by substrate-level phosphorylation, NADH and FADH The negative ΔG indicates that the reaction can occur spontaneously. The potential of NADH and FADH is converted to more ATP through an electron transport chain with oxygen as the "terminal electron acceptor". Most of the ATP produced by aerobic cellular respiration is made by oxidative phosphorylation. This works by the energy released in the consumption of pyruvate being used to create a chemiosmotic potential by pumping protons across a membrane. This potential is then used to drive ATP synthase and produce ATP from

pos: Glucose for subsequent breakdown in later steps of glycolysis. At physiological conditions, this initial reaction is irreversible. In anaerobic respiration, one glucose molecule produces a net gain of two ATP molecules (four ATP molecules are produced during glycolysis through substrate-level phosphorylation, but two are required by enzymes used during the process). In aerobic respiration, a molecule of glucose is much more profitable in that a maximum net production of 30 or 32 ATP molecules (depending on the organism) through oxidative phosphorylation is generated. Tumor cells often grow comparatively quickly and consume an above-average amount of glucose by glycolysis, which leads to

pos: Dioxygen in biological reactions a waste product, is released from the cell and into the blood, where it combines with bicarbonate and hemoglobin for transport to the lungs. Blood circulates back to the lungs and the process repeats. Molecular oxygen, O, is essential for cellular respiration in all aerobic organisms. Oxygen is used as an electron acceptor in mitochondria to generate chemical energy in the form of adenosine triphosphate (ATP) during oxidative phosphorylation. The reaction for the aerobic respiration is essentially the reverse of photosynthesis, except that now there is a large release of chemical energy that is stored in ATP molecules (up to

pos: Adenosine triphosphate pathways in eukaryotes are (1) glycolysis, (2) the citric acid cycle/oxidative phosphorylation, and (3) beta-oxidation. The overall process of oxidizing glucose to carbon dioxide, the combination of pathways 1 and 2, is known as cellular respiration, produces about 30 equivalents of ATP from each molecule of glucose. ATP production by a non-photosynthetic aerobic eukaryote occurs mainly in the mitochondria, which comprise nearly 25% of the volume of a typical cell. In glycolysis, glucose and glycerol are metabolized to pyruvate. Glycolysis generates two equivalents of ATP through substrate phosphorylation catalyzed by two enzymes, PGK and pyruvate kinase. Two equivalents of NADH

pos: Cellular respiration However some anaerobic organisms, such as methanogens are able to continue with anaerobic respiration, yielding more ATP by using other inorganic molecules (not oxygen) as final electron acceptors in the electron transport chain. They share the initial pathway of glycolysis but aerobic metabolism continues with the Krebs cycle and oxidative phosphorylation. The post-glycolytic reactions take place in the mitochondria in eukaryotic cells, and in the cytoplasm in prokaryotic cells. 1. Glycolysis: --- "2 ATPs + Glucose → 2 Pyruvic Acid + 4 Hydrogen + 4 ATPs" 2. Formation of Acetyl CoA: --- "2 Pyruvic Acid + 2 CoA → 2

pos: Adenosine diphosphate the cytoplasm, the viscous fluid that fills living cells, where the glycolytic reactions take place. The citric acid cycle, also known as the Krebs cycle or the TCA (tricarboxylic acid) cycle is an 8-step process that takes the pyruvate generated by glycolysis and generates 4 NADH, FADH2, and GTP, which is further converted to ATP. It is only in step 5, where GTP is generated, by succinyl-CoA synthetase, and then converted to ATP, that ADP is used (GTP + ADP → GDP + ATP). Oxidative phosphorylation produces 26 of the 30 equivalents of ATP generated in cellular respiration by transferring

pos: Cellular respiration coenzymes are oxidized by the electron transport chain and used for oxidative phosphorylation. Although there is a theoretical yield of 38 ATP molecules per glucose during cellular respiration, such conditions are generally not realized because of losses such as the cost of moving pyruvate (from glycolysis), phosphate, and ADP (substrates for ATP synthesis) into the mitochondria. All are actively transported using carriers that utilize the stored energy in the proton electrochemical gradient. The outcome of these transport processes using the proton electrochemical gradient is that more than 3 H are needed to make 1 ATP. Obviously this reduces the theoretical

pos: Cellular waste product CO is formed in Pyruvate decarboxylation, HO is formed in oxidative phosphorylation, and both are formed in the citric acid cycle. The simple nature of the final products also indicates the efficiency of this method of respiration. All of the energy stored in the carbon-carbon bonds of glucose is released, leaving CO and HO. Although there is energy stored in the bonds of these molecules, this energy is not easily accessible by the cell. All usable energy is efficiently extracted. Anaerobic respiration is done by aerobic organisms when there is not sufficient oxygen in a cell to undergo aerobic respiration

pos: Substrate-level phosphorylation Substrate-level phosphorylation Substrate-level phosphorylation is a metabolic reaction that results in the formation of ATP or GTP by the direct transfer of a phosphoryl (PO) group to ADP or GDP from another phosphorylated compound. Unlike oxidative phosphorylation, oxidation and phosphorylation are not coupled in the process of substrate-level phosphorylation, and reactive intermediates are most often gained in the course of oxidation processes in catabolism. Most ATP is generated by oxidative phosphorylation in aerobic or anaerobic respiration while substrate-level phosphorylation provides a quicker, less efficient source of ATP, independent of external electron acceptors. This is the case in human erythrocytes, which

pos: Electron transport chain aerobic respiration is molecular oxygen although a variety of acceptors other than oxygen such as sulfate exist in anaerobic respiration. Electron transport chains are used for extracting energy via redox reactions from sunlight in photosynthesis or, such as in the case of the oxidation of sugars, cellular respiration. In eukaryotes, an important electron transport chain is found in the inner mitochondrial membrane where it serves as the site of oxidative phosphorylation through the action of ATP synthase. It is also found in the thylakoid membrane of the chloroplast in photosynthetic eukaryotes. In bacteria, the electron transport chain is located in

pos: Obligate anaerobe is no oxidative phosphorylation). Numerous fermentation pathways exist e.g. lactic acid fermentation, mixed acid fermentation, 2-3 butanediol fermentation. The energy yield of anaerobic respiration and fermentation (i.e. the number of ATP molecules generated) is less than in aerobic respiration. This is why facultative anaerobes, which can metabolise energy both aerobically and anaerobically, preferentially metabolise energy aerobically. This is observable when facultative anaerobes are cultured in thioglycollate broth. Examples of obligately anaerobic bacterial genera include "Actinomyces", "Bacteroides", "Clostridium", "Fusobacterium", "Peptostreptococcus", "Porphyromonas", "Prevotella", "Propionibacterium", and "Veillonella". "Clostridium" species are endospore-forming bacteria, and can survive in atmospheric concentrations of oxygen in this dormant

pos: Chemiosmosis one of the major eukaryotic supergroups. Chemiosmotic phosphorylation is the third pathway that produces ATP from inorganic phosphate and an ADP molecule. This process is part of oxidative phosphorylation. Chemiosmosis Chemiosmosis is the movement of ions across a semipermeable membrane, down their electrochemical gradient. An example of this would be the generation of adenosine triphosphate (ATP) by the movement of hydrogen ions (H) across a membrane during cellular respiration or photosynthesis. Hydrogen ions, or protons, will diffuse from an area of high proton concentration to an area of lower proton concentration, and an electrochemical concentration gradient of protons across a

pos: Exoelectrogen Exoelectrogen An exoelectrogen normally refers to a microorganism that has the ability to transfer electrons extracellularly. While exoelectrogen is the predominant name, other terms have been used: electrochemically active bacteria, anode respiring bacteria, and electricigens. Electrons exocytosed in this fashion are produced following ATP production using an electron transport chain (ETC) during oxidative phosphorylation. Conventional cellular respiration requires a final electron acceptor to receive these electrons. Cells that use molecular oxygen (O) as their final electron acceptor are described as using aerobic respiration, while cells that use other soluble compounds as their final electron acceptor are described as using anaerobic

pos: Oxidative phosphorylation produces reactive oxygen species such as superoxide and hydrogen peroxide, which lead to propagation of free radicals, damaging cells and contributing to disease and, possibly, aging (senescence). The enzymes carrying out this metabolic pathway are also the target of many drugs and poisons that inhibit their activities. It is the terminal process of cellular respiration in eukaryotes and accounts for high ATP yield. Oxidative phosphorylation works by using energy-releasing chemical reactions to drive energy-requiring reactions: The two sets of reactions are said to be "coupled". This means one cannot occur without the other. The flow of electrons through the electron

pos: Carbohydrate catabolism of electrons, is used to reduce NAD+ and FAD to NADH and FADH, respectively. NADH and FADH contain the stored energy harnessed from the initial glucose molecule and is used in the electron transport chain where the bulk of the ATP is produced. The last process in aerobic respiration is oxidative phosphorylation, also known as the electron transport chain. Here NADH and FADH, which contain the energy in the form of electrons, deliver their electrons to the inner membranes of the mitochondrion to power the production of ATP. Oxidative phosphorylation contributes the majority of the ATP produced, compared to glycolysis

pos: ADP/ATP translocase the matrix. Binding of ATP from the matrix induces eversion and results in the release of ATP into the intermembrane space, subsequently diffusing to the cytoplasm, and concomitantly brings the translocase back to its original conformation. ATP and ADP are the only natural nucleotides recognized by the translocase. The net process is denoted by: ADP/ATP exchange is energetically expensive: about 25% of the energy yielded from electron transfer by aerobic respiration, or one hydrogen ion, is consumed to regenerate the membrane potential that is tapped by ADP/ATP translocase. ADP/ATP translocase transports ATP synthesized from oxidative phosphorylation into the cytoplasm, where

pos: Substrate-level phosphorylation erroneously considered to be substrate-level phosphorylation, although it is a transphosphorylation. During anoxia, provision of ATP by substrate-level phosphorylation in the matrix is important not only as a mere means of energy, but also to prevent mitochondria from straining glycolytic ATP reserves by maintaining the adenine nucleotide translocator in ‘forward mode’ carrying ATP towards the cytosol . An alternative method used to create ATP is through oxidative phosphorylation, which takes place during cellular respiration. This process utilizes the oxidation of NADH to NAD, yielding 3 ATP, and of FADH to FAD, yielding 2 ATP. The potential energy stored as an

pos: Adenosine triphosphate by oxidative phosphorylation. The oxidation of NADH results in the synthesis of 2–3 equivalents of ATP, and the oxidation of one FADH yields between 1–2 equivalents of ATP. The majority of cellular ATP is generated by this process. Although the citric acid cycle itself does not involve molecular oxygen, it is an obligately aerobic process because O is used to recycle the NADH and FADH. In the absence of oxygen, the citric acid cycle ceases. The generation of ATP by the mitochondrion from cytosolic NADH relies on the malate-aspartate shuttle (and to a lesser extent, the glycerol-phosphate shuttle) because the

pos: Bioenergetic systems total NADH+ molecules allow the rejuvenation of 30 ATP, and 2 FADH+ molecules allow for 4 ATP molecules to be rejuvenated (the total being 34 from oxidative phosphorylation, plus the 4 from the previous 2 stages meaning a total of 38 ATP being produced during the aerobic system). The NADH+ and FADH+ get oxidized to allow the NAD and FAD to return to be used in the aerobic system again, and electrons and hydrogen ions are accepted by oxygen to produce water, a harmless byproduct. Bioenergetic systems Bioenergetic systems are metabolic processes that relate to the flow of energy in

neg: Carbohydrate catabolism molecules of ATP is therefore one of the most important biochemical pathways found in living organisms. Glycolysis, which means “sugar splitting,” is the initial process in the cellular respiration pathway. Glycolysis can be either an aerobic or anaerobic process. When oxygen is present, glycolysis continues along the aerobic respiration pathway. If oxygen is not present, then ATP production is restricted to anaerobic respiration. The location where glycolysis, aerobic or anaerobic, occurs is in the cytosol of the cell. In glycolysis, a six-carbon glucose molecule is split into two three-carbon molecules called pyruvate. These carbon molecules are oxidized into NADH and

neg: Cellular waste product Cellular waste product Cellular waste products are formed as a by-product of cellular respiration, a series of processes and reactions that generate energy for the cell, in the form of ATP. Two examples of cellular respiration creating cellular waste products are aerobic respiration and anaerobic respiration. Each pathway generates different waste products. When in the presence of oxygen, cells use aerobic respiration to obtain energy from glucose molecules. Simplified Theoretical Reaction: CHO + 6O → 6CO + 6HO + ~ 30ATP Cells undergoing aerobic respiration produce 6 molecules of carbon dioxide, 6 molecules of water, and up to 30 molecules

neg: Cellular waste product of oxygen, not all of the carbon-carbon bonds in glucose can be broken to release energy. A great deal of extractable energy is left in the waste products. Anaerobic respiration generally occurs in prokaryotes in environments that do not contain oxygen. Fermentation is another process by which cells can extract energy from glucose. It is not a form of cellular respiration, but it does generate ATP, break down glucose, and produce waste products. Fermentation, like aerobic respiration, begins by breaking glucose into two pyruvate molecules. From here, it proceeds using endogenous organic electron receptors, whereas cellular respiration uses exogenous receptors,

neg: Cellular respiration ADP and a phosphate group. Biology textbooks often state that 38 ATP molecules can be made per oxidised glucose molecule during cellular respiration (2 from glycolysis, 2 from the Krebs cycle, and about 34 from the electron transport system). However, this maximum yield is never quite reached because of losses due to leaky membranes as well as the cost of moving pyruvate and ADP into the mitochondrial matrix, and current estimates range around 29 to 30 ATP per glucose. Aerobic metabolism is up to 15 times more efficient than anaerobic metabolism (which yields 2 molecules ATP per 1 molecule glucose).

neg: Cellular waste product along the same pathway as aerobic respiration, but once glucose is converted to pyruvate proceeds down one of two pathways and produces only two molecules of ATP from each molecule of glucose. In the homolactic pathway, it produces lactic acid as waste. In the heterolactic pathway, it produces lactic acid as well as ethanol and carbon dioxide. Lactic acid fermentation is relatively inefficient. The waste products lactic acid and ethanol have not been fully oxidized and still contain energy, but it requires the addition of oxygen to extract this energy. Generally, lactic acid fermentation occurs only when aerobic cells are

neg: Cellular respiration lactate. In aerobic conditions, the process converts one molecule of glucose into two molecules of pyruvate (pyruvic acid), generating energy in the form of two net molecules of ATP. Four molecules of ATP per glucose are actually produced, however, two are consumed as part of the preparatory phase. The initial phosphorylation of glucose is required to increase the reactivity (decrease its stability) in order for the molecule to be cleaved into two pyruvate molecules by the enzyme aldolase. During the pay-off phase of glycolysis, four phosphate groups are transferred to ADP by substrate-level phosphorylation to make four ATP, and two

neg: Glycolysis as part of glycolysis. These further aerobic reactions use pyruvate and NADH + H from glycolysis. Eukaryotic aerobic respiration produces approximately 34 additional molecules of ATP for each glucose molecule, however most of these are produced by a vastly different mechanism to the substrate-level phosphorylation in glycolysis. The lower-energy production, per glucose, of anaerobic respiration relative to aerobic respiration, results in greater flux through the pathway under hypoxic (low-oxygen) conditions, unless alternative sources of anaerobically oxidizable substrates, such as fatty acids, are found. The pathway of glycolysis as it is known today took almost 100 years to fully discover. The

neg: Cellular respiration to make ATP but generates heat. This is particularly important in brown fat thermogenesis of newborn and hibernating mammals. According to some of newer sources the ATP yield during aerobic respiration is not 36–38, but only about 30–32 ATP molecules / 1 molecule of glucose , because: So finally we have, per molecule of glucose Altogether this gives 4 + 3 (or 5) + 20 + 3 = 30 (or 32) ATP per molecule of glucose The total ATP yield in ethanol or lactic acid fermentation is only 2 molecules coming from glycolysis, because pyruvate is not transferred to the

neg: Cellular respiration pace themselves, such as sprinting. Cellular respiration is the process by which biological fuels are oxidised in the presence of an inorganic electron acceptor (such as oxygen) to produce large amounts of energy, to drive the bulk production of ATP. Anaerobic respiration is used by some microorganisms in which neither oxygen (aerobic respiration) nor pyruvate derivatives (fermentation) is the final electron acceptor. Rather, an inorganic acceptor such as sulfate or nitrate is used. Such organisms are typically found in unusual places such as underwater caves or near hydrothermal vents at the bottom of the ocean. Cellular respiration Cellular respiration is

neg: Food energy or cooler – increase the metabolic rate, thus burning more energy. Prolonged exposure to extremely warm or very cold environments increases the basal metabolic rate (BMR). People who live in these types of settings often have BMRs 5–20% higher than those in other climates. Food energy Food energy is chemical energy that animals (including humans) derive from food through the process of cellular respiration. Cellular respiration may either involve the chemical reaction of food molecules with molecular oxygen (aerobic respiration) or the process of reorganizing the food molecules without additional oxygen (anaerobic respiration). Humans and other animals need a minimum

neg: Food energy Food energy Food energy is chemical energy that animals (including humans) derive from food through the process of cellular respiration. Cellular respiration may either involve the chemical reaction of food molecules with molecular oxygen (aerobic respiration) or the process of reorganizing the food molecules without additional oxygen (anaerobic respiration). Humans and other animals need a minimum intake of food energy to sustain their metabolism and to drive their muscles. Foods are composed chiefly of carbohydrates, fats, proteins, water, vitamins, and minerals. Carbohydrates, fats, proteins, and water represent virtually all the weight of food, with vitamins and minerals making up only

neg: Cellular respiration stronger bonds to form, thereby transferring energy for use by the cell) can then be used to drive processes requiring energy, including biosynthesis, locomotion or transportation of molecules across cell membranes. "Aerobic respiration" requires oxygen (O) in order to create ATP. Although carbohydrates, fats, and proteins are consumed as reactants, it is the preferred method of pyruvate breakdown in glycolysis and requires that pyruvate enter the mitochondria in order to be fully oxidized by the Krebs cycle. The products of this process are carbon dioxide and water, but the energy transferred is used to break bonds in ADP as the

neg: Cellular respiration Cellular respiration Cellular respiration is a set of metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. The reactions involved in respiration are catabolic reactions, which break large molecules into smaller ones, releasing energy in the process, as weak so-called "high-energy" bonds are replaced by stronger bonds in the products. Respiration is one of the key ways a cell releases chemical energy to fuel cellular activity. Cellular respiration is considered an exothermic redox reaction which releases heat. The overall reaction occurs in

neg: Cellular waste product of ATP (adenosine triphosphate), which is directly used to produce energy, from each molecule of glucose in the presence of surplus oxygen. In aerobic respiration, oxygen serves as the recipient of electrons from the electron transport chain. Aerobic respiration is thus very efficient because oxygen is a strong oxidant. Aerobic respiration proceeds in a series of steps, which also increases efficiency - since glucose is broken down gradually and ATP is produced as needed, less energy is wasted as heat. This strategy results in the waste products HO and CO being formed in different amounts at different phases of respiration.

neg: Soil respiration tricarboxylic acid (TCA) cycle – or citric acid cycle – is an important step in cellular respiration. In the TCA cycle, a six carbon sugar will be oxidized. This oxidation produces the CO and HO from the sugar. Plants, fungi, animals and bacteria all use this cycle to convert organic compounds to energy. This is how the majority of soil respiration occurs at its most basic level. Since the process relies on oxygen to occur, this is referred to as aerobic respiration. Fermentation is another process in which cells gain energy from organic compounds. In this metabolic pathway, energy is

neg: Cellular waste product fatigue. It also creates a gradient which induces water to flow out of cells and increases blood pressure. Research suggests that lactic acid may also play a role in lowering levels of potassium in the blood. It can also be converted back to pyruvate or converted back to glucose in the liver and fully metabolized by aerobic respiration. Cellular waste product Cellular waste products are formed as a by-product of cellular respiration, a series of processes and reactions that generate energy for the cell, in the form of ATP. Two examples of cellular respiration creating cellular waste products are aerobic

neg: Cellular respiration glycogen. During recovery, when oxygen becomes available, NAD+ attaches to hydrogen from lactate to form ATP. In yeast, the waste products are ethanol and carbon dioxide. This type of fermentation is known as alcoholic or ethanol fermentation. The ATP generated in this process is made by substrate-level phosphorylation, which does not require oxygen. Fermentation is less efficient at using the energy from glucose: only 2 ATP are produced per glucose, compared to the 38 ATP per glucose nominally produced by aerobic respiration. This is because the waste products of fermentation still contain chemical potential energy that can be released by

neg: Plant nutrition photosynthesis and for respiration. Oxygen is a component of many organic and inorganic molecules within the plant, and is acquired in many forms. These include: O and CO (mainly from the air via leaves) and HO, NO, HPO and SO (mainly from the soil water via roots). Plants produce oxygen gas (O) along with glucose during photosynthesis but then require O to undergo aerobic cellular respiration and break down this glucose to produce ATP. Nitrogen is a major constituent of several of the most important plant substances. For example, nitrogen compounds comprise 40% to 50% of the dry matter of

neg: Breathing Breathing Breathing (or respiration, or ventilation) is the process of moving air into and out of the lungs to facilitate gas exchange with the internal environment, mostly by bringing in oxygen and flushing out carbon dioxide. All aerobic creatures need oxygen for cellular respiration, which uses the oxygen to break down foods for energy and produces carbon dioxide as a waste product. Breathing, or "external respiration", brings air into the lungs where gas exchange takes place in the alveoli through diffusion. The body's circulatory system transports these gases to and from the cells, where "cellular respiration" takes place. The breathing

neg: Bioenergetic systems and intensity and by the individual's cardiorespiratory fitness level. Three exercise energy systems can be selectively recruited, depending on the amount of oxygen available, as part of the cellular respiration process to generate the ATP for the muscles. They are ATP, the anaerobic system and the aerobic system. ATP is the usable form of chemical energy for muscular activity. It is stored in most cells, particularly in muscle cells. Other forms of chemical energy, such as those available from food, must be transformed into ATP before they can be utilized by the muscle cells. Since energy is released when ATP

neg: Mitochondrion cycle. However, the mitochondrion has many other functions in addition to the production of ATP. A dominant role for the mitochondria is the production of ATP, as reflected by the large number of proteins in the inner membrane for this task. This is done by oxidizing the major products of glucose: pyruvate, and NADH, which are produced in the cytosol. This type of cellular respiration known as aerobic respiration, is dependent on the presence of oxygen. When oxygen is limited, the glycolytic products will be metabolized by anaerobic fermentation, a process that is independent of the mitochondria. The production of

neg: Chemiosmosis from the cytoplasm. This "costs" one "extra" proton import per ATP, hence the actual efficiency is only 65% (= 2.4/3.67). The complete breakdown of glucose in the presence of oxygen is called cellular respiration. The last steps of this process occur in mitochondria. The reduced molecules NADH and FADH are generated by the Krebs cycle, glycolysis, and pyruvate processing. These molecules pass electrons to an electron transport chain, which uses the energy released to create a proton gradient across the inner mitochondrial membrane. ATP synthase then uses the energy stored in this gradient to make ATP. This process is called

neg: Obligate aerobe Obligate aerobe An obligate aerobe is an organism that requires oxygen to grow. Through cellular respiration, these organisms use oxygen to metabolise substances, like sugars or fats, to obtain energy. In this type of respiration, oxygen serves as the terminal electron acceptor for the electron transport chain. Aerobic respiration has the advantage of yielding more energy (adenosine triphosphate or ATP) than fermentation or anaerobic respiration, but obligate aerobes are subject to high levels of oxidative stress. Examples of obligately aerobic bacteria include and "Mycobacterium tuberculosis" and "Nocardia asteroides". With the exception of the yeasts, most fungi are obligate aerobes. Also,

neg: Bioenergetic systems Bioenergetic systems Bioenergetic systems are metabolic processes that relate to the flow of energy in living organisms. Those processes convert energy into adenosine triphosphate (ATP), which is the form suitable for muscular activity. There are two main forms of synthesis of ATP: "aerobic", which involves oxygen from the bloodstream, and "anaerobic", which does not. Bioenergetics is the field of biology that studies bioenergetic systems. The cellular respiration process that converts food energy into ATP (a form of energy) is largely dependent on oxygen availability. During exercise, the supply and demand of oxygen available to muscle cells is affected by duration

neg: Aerobic fermentation cells have higher energy demands due to the continued proliferation and respiration produces significantly more ATP than glycolysis alone (fermentation produces no additional ATP). Typically, there is an up-regulation in glucose transporters and enzymes in the glycolysis pathway (also seen in yeast). There are many parallel aspects of aerobic fermentation in tumor cells that are also seen in Crabtree-positive yeasts. Further research into the evolution of aerobic fermentation in yeast such as "S. cerevisiae" can be a useful model for understanding aerobic fermentation in tumor cells. This has a potential for better understanding cancer and cancer treatments. Aerobic fermentation Aerobic

neg: Cellular waste product such as oxygen in aerobic respiration and nitrate in anaerobic respiration. These varied organic receptors each generate different waste products. Common products are lactic acid, lactose, hydrogen, and ethanol. Carbon dioxide is also commonly produced. Fermentation occurs primarily in anaerobic conditions, although some organisms such as yeast use fermentation even when oxygen is plentiful. Simplified Theoretical Reaction: CHO formula_1 2CHO + 2 ATP (120 kJ) Lactic Acid Fermentation is commonly known as the process by which mammalian muscle cells produce energy in anaerobic environments, as in instances of great physical exertion, and is the simplest type of fermentation. It starts

neg: Carbohydrate metabolism FADH, which drive the creation of ATP in other processes. A molecule of NADH can produce 1.5–2.5 molecules of ATP, whereas a molecule of FADH will yield 1.5 molecules of ATP. Typically, the complete breakdown of one molecule of glucose via aerobic respiration (i.e. involving both glycolysis and the Citric Acid Cycle) is usually about 30–32 molecules of ATP. Oxidation of one gram of carbohydrate yields approximately 4 kcal of energy. Glucoregulation is the maintenance of steady levels of glucose in the body. Hormones released from the pancreas regulate the overall metabolism of glucose. Insulin and glucagon are the primary

neg: Cellular respiration oxidation. Ethanol, for example, can be burned in an internal combustion engine like gasoline. Glycolytic ATP, however, is created more quickly. For prokaryotes to continue a rapid growth rate when they are shifted from an aerobic environment to an anaerobic environment, they must increase the rate of the glycolytic reactions. For multicellular organisms, during short bursts of strenuous activity, muscle cells use fermentation to supplement the ATP production from the slower aerobic respiration, so fermentation may be used by a cell even before the oxygen levels are depleted, as is the case in sports that do not require athletes to

neg: Obligate aerobe almost all algae are obligate aerobes. Obligate aerobe An obligate aerobe is an organism that requires oxygen to grow. Through cellular respiration, these organisms use oxygen to metabolise substances, like sugars or fats, to obtain energy. In this type of respiration, oxygen serves as the terminal electron acceptor for the electron transport chain. Aerobic respiration has the advantage of yielding more energy (adenosine triphosphate or ATP) than fermentation or anaerobic respiration, but obligate aerobes are subject to high levels of oxidative stress. Examples of obligately aerobic bacteria include and "Mycobacterium tuberculosis" and "Nocardia asteroides". With the exception of the yeasts,

neg: Carbohydrate catabolism Carbohydrate catabolism Digestion is the breakdown of carbohydrates to yield an energy rich compound called ATP. The production of ATP is achieved through the oxidation of glucose molecules. In oxidation, the electrons are stripped from a glucose molecule to reduce NAD+ and FAD. NAD+ and FAD possess a high energy potential to drive the production of ATP in the electron transport chain. ATP production occurs in the mitochondria of the cell. There are two methods of producing ATP: aerobic and anaerobic. In aerobic respiration, oxygen is required. Oxygen plays a key role as it increases ATP production from 4 ATP

neg: Muscle form of creatine phosphate which is generated from ATP and can regenerate ATP when needed with creatine kinase. Muscles also keep a storage form of glucose in the form of glycogen. Glycogen can be rapidly converted to glucose when energy is required for sustained, powerful contractions. Within the voluntary skeletal muscles, the glucose molecule can be metabolized anaerobically in a process called glycolysis which produces two ATP and two lactic acid molecules in the process (note that in aerobic conditions, lactate is not formed; instead pyruvate is formed and transmitted through the citric acid cycle). Muscle cells also contain globules

neg: Cellular waste product as well as by cells called anaerobes that selectively perform anaerobic respiration even in the presence of oxygen. In anaerobic respiration, weak oxidants like sulfate and nitrate serve as oxidants in the place of oxygen. Generally, in anaerobic respiration sugars are broken down into carbon dioxide and other waste products that are dictated by the oxidant the cell uses. Whereas in aerobic respiration the oxidant is always oxygen, in anaerobic respiration it varies. Each oxidant produces a different waste product, such as nitrite, succinate, sulfide, methane, and acetate. Anaerobic respiration is correspondingly less efficient than aerobic respiration. In the absence

neg: Cellular respiration oxidized to acetyl-CoA and CO by the pyruvate dehydrogenase complex (PDC). The PDC contains multiple copies of three enzymes and is located in the mitochondria of eukaryotic cells and in the cytosol of prokaryotes. In the conversion of pyruvate to acetyl-CoA, one molecule of NADH and one molecule of CO is formed. This is also called the "Krebs cycle" or the "tricarboxylic acid cycle". When oxygen is present, acetyl-CoA is produced from the pyruvate molecules created from glycolysis. Once acetyl-CoA is formed, aerobic or anaerobic respiration can occur. When oxygen is present, the mitochondria will undergo aerobic respiration which leads

neg: Lonidamine Lonidamine Lonidamine is a derivative of indazole-3-carboxylic acid, which for a long time, has been known to inhibit aerobic glycolysis in cancer cells. It seems to enhance aerobic glycolysis in normal cells, but suppress glycolysis in cancer cells. This is most likely through the inhibition of the mitochondrially bound hexokinase. Later studies in Ehrlich ascites tumor cells showed that lonidamine inhibits both respiration and glycolysis leading to a decrease in cellular ATP. Clinical trials of lonidamine in combination with other anticancer agents for a variety of cancers has begun. This is due to its proven ability to inhibit energy metabolism

neg: Respiration (physiology) Respiration (physiology) In physiology, respiration is the movement of oxygen from the outside environment to the cells within tissues, and the transport of carbon dioxide in the opposite direction. The physiological definition of respiration differs from the biochemical definition, which refers to cellular respiration, a metabolic process by which an organism obtains energy (in the form of ATP) by oxidizing nutrients and releasing waste products. Although physiologic respiration is necessary to sustain cellular respiration and thus life in animals, the processes are distinct: cellular respiration takes place in individual cells of the organism, while physiologic respiration concerns the diffusion and

neg: Glycolysis four hydroxyl groups, giving ATPMg. When these differences along with the true charges on the two phosphate groups are considered together, the net charges of −4 on each side are balanced. For simple fermentations, the metabolism of one molecule of glucose to two molecules of pyruvate has a net yield of two molecules of ATP. Most cells will then carry out further reactions to 'repay' the used NAD and produce a final product of ethanol or lactic acid. Many bacteria use inorganic compounds as hydrogen acceptors to regenerate the NAD. Cells performing aerobic respiration synthesize much more ATP, but not

neg: Oxygen extant anaerobic organisms to extinction during the Great Oxygenation Event ("oxygen catastrophe") about 2.4 billion years ago. Cellular respiration using enables aerobic organisms to produce much more ATP than anaerobic organisms. Cellular respiration of occurs in all eukaryotes, including all complex multicellular organisms such as plants and animals. Since the beginning of the Cambrian period 540 million years ago, atmospheric levels have fluctuated between 15% and 30% by volume. Towards the end of the Carboniferous period (about 300 million years ago) atmospheric levels reached a maximum of 35% by volume, which may have contributed to the large size of insects

neg: Second wind exercise as well as other cellular functions requires oxygen to produce ATP and properly function. This normal function is called aerobic metabolism and does not produce lactic acid if enough oxygen is present. During heavy exercise such as long distance running or any demanding exercise, the body's need for oxygen to produce energy is higher than the oxygen supplied in the blood from respiration. Anaerobic metabolism to some degree then takes place in the muscle and this less ideal energy production produces lactic acid as a waste metabolite. If the oxygen supply is not soon restored, this may lead to

neg: Muscular system can not be removed immediately from the sarcomere and the body, and it results in a much greater number of ATP molecules per fat or carbohydrate molecule. Aerobic training allows the oxygen delivery system to be more efficient, allowing aerobic metabolism to begin quicker. Anaerobic ATP production produces ATP much faster and allows near-maximal intensity exercise, but also produces significant amounts of lactic acid which renders high-intensity exercise unsustainable for more than several minutes. The phosphagen system is also anaerobic. It allows for the highest levels of exercise intensity, but intramuscular stores of phosphocreatine are very limited and can only

neg: Cellular waste product lacking oxygen. However, some aerobic mammalian cells will preferentially use lactic acid fermentation over aerobic respiration. This phenomenon is called the Warburg effect and is found primarily in cancer cells. Muscles cells under great exertion will also use lactic acid fermentation to supplement aerobic respiration. Lactic acid fermentation is somewhat faster, although less efficient, than aerobic respiration, so in activities like sprinting it can help quickly provide needed energy to muscles. Cellular respiration takes place in the cristae of the mitochondria within cells. Depending on the pathways followed, the products are dealt with in different ways. CO is excreted from

neg: Cellular respiration efficiency of the whole process and the likely maximum is closer to 28–30 ATP molecules. In practice the efficiency may be even lower because the inner membrane of the mitochondria is slightly leaky to protons. Other factors may also dissipate the proton gradient creating an apparently leaky mitochondria. An uncoupling protein known as thermogenin is expressed in some cell types and is a channel that can transport protons. When this protein is active in the inner membrane it short circuits the coupling between the electron transport chain and ATP synthesis. The potential energy from the proton gradient is not used

neg: Adenosine diphosphate performed via aerobic respiration in the mitochondria. Plants use photosynthetic pathways to convert and store energy from sunlight, also conversion of ADP to ATP. Animals use the energy released in the breakdown of glucose and other molecules to convert ADP to ATP, which can then be used to fuel necessary growth and cell maintenance. The ten-step catabolic pathway of glycolysis is the initial phase of free-energy release in the breakdown of glucose and can be split into two phases, the preparatory phase and payoff phase. ADP and phosphate are needed as precursors to synthesize ATP in the payoff reactions of

neg: Carbohydrate one gram of lipids yields about 38 kJ (9 kcal). The human body stores between 300 to 500 g of carbohydrates depending on body weight, with the skeletal muscle contributing to a large portion of the storage. Energy obtained from metabolism (e.g., oxidation of glucose) is usually stored temporarily within cells in the form of ATP. Organisms capable of anaerobic and aerobic respiration that metabolizes glucose and oxygen (aerobic) to release energy with carbon dioxide and water as byproducts. Catabolism is the metabolic reaction which cells undergo to break down larger molecules, extracting energy. There are two major metabolic pathways

neg: Fermentation theory our their anaerobic respiration to survive. Even the human body carries out fermentation processes from time to time. When someone runs a long distance race, lactic acid will build up in their muscles over the course of the race. That lactic acid is the by-product of fermentation taking place in their body, which tries to produce ATP so the body can continue to run since they could not process the oxygen intake fast enough. Although fermentation will give a lower yield of ATP production than aerobic respiration does, it can occur at a much higher rate. Fermentation has been used

neg: Denitrifying bacteria an aerobic respiratory process in which nitrate is converted gradually to N (NO →NO → NO → NO → N ), using nitrate reductase (Nar or Nao), nitrite reductase (Nir), nitric oxide reductase (Nor), and nitrous oxide reductase (Nos). Phylogenetic analysis revealed that aerobic denitrifiers mainly belong to α-, β- and γ-"Proteobacteria". Denitrifying bacteria use denitrification to generate ATP. The most common denitrification process is outlined below, with the nitrogen oxides being converted back to gaseous nitrogen: 2 NO + 10 e + 12 H → N + 6 HO The result is one molecule of nitrogen and six molecules

neg: Lactic acid fermentation Lactic acid fermentation Lactic acid fermentation is a metabolic process by which glucose and other six-carbon sugars (also, disaccharides of six-carbon sugars, e.g. sucrose or lactose) are converted into cellular energy and the metabolite lactate, which is lactic acid in solution. It is an anaerobic fermentation reaction that occurs in some bacteria and animal cells, such as muscle cells. If oxygen is present in the cell, many organisms will bypass fermentation and undergo cellular respiration; however, facultative anaerobic organisms will both ferment and undergo respiration in the presence of oxygen. Sometimes even when oxygen is present and aerobic metabolism is

neg: TP53-inducible glycolysis and apoptosis regulator unknown. TIGAR can promote development or inhibition of several cancers depending on the cellular context. TIGAR can have some effect on three characteristics of cancer; the ability to evade apoptosis, uncontrolled cell division, and altered metabolism. Many cancer cells have altered metabolism where the rate of glycolysis and anaerobic respiration are very high whilst oxidative respiration is low, which is called the Warburg Effect (or aerobic glycolysis). This allows cancer cells to survive under low oxygen conditions, and use molecules from respiratory pathways to synthesise amino acids and nucleic acids to maintain rapid growth. In Glioma, a type of brain

neg: Ethanol fermentation Other microorganisms can produce ethanol from sugars by fermentation but often only as a side product. Examples are Fermentation does not require oxygen. If oxygen is present, some species of yeast (e.g., "Kluyveromyces lactis" or "Kluyveromyces lipolytica") will oxidize pyruvate completely to carbon dioxide and water in a process called cellular respiration, hence these species of yeast will produce ethanol only in an anaerobic environment (not cellular respiration). However, many yeasts such as the commonly used baker's yeast "Saccharomyces cerevisiae", or fission yeast "Schizosaccharomyces pombe", prefer fermentation to respiration. These yeasts will produce ethanol even under aerobic conditions, if they

neg: Mitochondrion ATP from glucose has an approximately 13-times higher yield during aerobic respiration compared to fermentation. Plant mitochondria can also produce a limited amount of ATP without oxygen by using the alternate substrate nitrite. ATP crosses out through the inner membrane with the help of a specific protein, and across the outer membrane via porins. ADP returns via the same route. Pyruvate molecules produced by glycolysis are actively transported across the inner mitochondrial membrane, and into the matrix where they can either be oxidized and combined with coenzyme A to form CO, acetyl-CoA, and NADH, or they can be carboxylated (by

neg: Beer chemistry yeast is a significant factor. In aerobic conditions, the yeast will use the simple sugars from the malting process in glycolysis, and send the major organic product of glycolysis (pyruvate) into carbon dioxide and water via cellular respiration, many homebrewers use this aspect of yeast metabolism to carbonate their beers. However, under anaerobic conditions yeast cannot use the end products of glycolysis to generate energy in cellular respiration. Instead, they rely on a process called fermentation. Fermentation converts pyruvate into ethanol through the intermediate acetaldehyde. Water can often play a very important role in the way a beer tastes, as

neg: Lily Young microorganisms in the environment are essentially carrying out oxidation and reduction reactions, namely, oxidation of the organic contaminant coupled to the reduction of inorganic electron acceptors. The mechanism by which these bacteria (mainly denitrifiers, iron reducers, sulfidogens and methanogens, respectively) degrade the contaminants is different from aerobic bacteria because they cannot use oxygen to activate the stable hydrocarbon molecules. In contrast to humans, these bacteria are not dependent on oxygen as an electron acceptor for cellular respiration, but use molecules like nitrate, iron, sulfate and carbonate. During her early research in the Environmental Engineering Program at Stanford University her groups

neg: Cellular respiration cycle. The citric acid cycle is an 8-step process involving 18 different enzymes and co-enzymes. During the cycle, acetyl-CoA (2 carbons) + oxaloacetate (4 carbons) yields citrate (6 carbons), which is rearranged to a more reactive form called isocitrate (6 carbons). Isocitrate is modified to become α-ketoglutarate (5 carbons), succinyl-CoA, succinate, fumarate, malate, and, finally, oxaloacetate. The net gain of high-energy compounds from one cycle is 3 NADH, 1 FADH, and 1 GTP; the GTP may subsequently be used to produce ATP. Thus, the total yield from 1 glucose molecule (2 pyruvate molecules) is 6 NADH, 2 FADH, and 2

neg: Maintenance respiration Maintenance respiration Maintenance respiration (or maintenance energy) refers to metabolism occurring in an organism that is needed to maintain that organism in a healthy, living state. Maintenance respiration in plants refers to the amount of cellular respiration, measured by the carbon dioxide (CO) released or oxygen (O) consumed, during the generation of usable energy (mainly ATP, NADPH, and NADH) and metabolic intermediates used for (i) resynthesis of compounds that undergo renewal (turnover) in the normal process of metabolism (examples are enzymatic proteins, ribonucleic acids, and membrane lipids); (ii) maintenance of chemical gradients of ions and metabolites across cellular membranes that

neg: Fermentation since the Neolithic age. For example, fermentation is used for preservation in a process that produces lactic acid found in such sour foods as pickled cucumbers, kimchi, and yogurt, as well as for producing alcoholic beverages such as wine and beer. Fermentation occurs within the gastrointestinal tracts of all animals, including humans. Below are some definitions of fermentation. They range from informal, general usages to more scientific definitions. Along with photosynthesis and aerobic respiration, fermentation is a way of extracting energy from molecules, but it is the only one common to all bacteria and eukaryotes. It is therefore considered the

neg: Biomedicine up the four big macromolecules that living organisms need to survive- carbohydrates, lipids, proteins, and nucleic acids. Carbohydrates, made up of carbon, hydrogen, and oxygen, are energy storing molecules. The simplest one of carbohydrates is glucose, CHO, is used in cellular respiration to produce ATP, adenosine triphosphate, which supplies cells with energy. Proteins are chains of amino acids that function to contract skeletal muscle, function catalysts, transport molecules, and storage molecules. Proteins can facilitate biochemical processes, by lowering the activation energy of a reaction. Hemoglobins are also proteins, that carry oxygen to the cells in an organisms body. Lipids, also

neg: Mitochondrion adenosine triphosphate (ATP) molecules, and, in 1941, the concept of the phosphate bonds of ATP being a form of energy in cellular metabolism was developed by Fritz Albert Lipmann. In the following years, the mechanism behind cellular respiration was further elaborated, although its link to the mitochondria was not known. The introduction of tissue fractionation by Albert Claude allowed mitochondria to be isolated from other cell fractions and biochemical analysis to be conducted on them alone. In 1946, he concluded that cytochrome oxidase and other enzymes responsible for the respiratory chain were isolated to the mitochondria. Eugene Kennedy and Albert

neg: Halophile as the deep salterns, where they tint the water column and sediments bright colors. These species most likely perish if they are exposed to anything other than a very high-concentration, salt-conditioned environment. These prokaryotes require salt for growth. The high concentration of sodium chloride in their environment limits the availability of oxygen for respiration. Their cellular machinery is adapted to high salt concentrations by having charged amino acids on their surfaces, allowing the retention of water molecules around these components. They are heterotrophs that normally respire by aerobic means. Most halophiles are unable to survive outside their high-salt native environments.

neg: Utricularia as little as 15 to 30 minutes. "Utricularia" have significantly greater respiration rates than most vegetative tissue, primarily due to their complex energy-dependent traps. Upon triggering, prey is captured through a two-step ATP-driven ion-pumping process where organisms are sucked in by internal negative pressure achieved by pumping water out of the trap and into the external environment. Recent research suggests that COX subunit I (COX1), a rate limiting enzyme in the cellular respiration pathway associated with the synthesis of ATP, has evolved under positive Darwinian selection in the "Utricularia"–"Genlisea" clade. There appear to be adaptive substitutions of two contiguous cysteines

neg: Cellular respiration a series of biochemical steps, most of which are redox reactions themselves. Although cellular respiration is technically a combustion reaction, it clearly does not resemble one when it occurs in a living cell because of the slow release of energy from the series of reactions. Nutrients that are commonly used by animal and plant cells in respiration include sugar, amino acids and fatty acids, and the most common oxidizing agent (electron acceptor) is molecular oxygen (O). The chemical energy stored in ATP (its third phosphate group is weakly bonded to the rest of the molecule and is cheaply broken allowing

neg: Abiogenesis which plays an essential role in cellular respiration and photosynthesis, more basal than fermentation: the ATP synthase enzyme, which sustains chemiosmosis, is proposed as the currently extant enzyme most closely related to the first metabolic process. First, life needed an energy source to bring about the condensation reaction that yielded the peptide bonds of proteins and the phosphodiester bonds of RNA. In a generalization and thermal variation of the binding change mechanism of today's ATP synthase, the "first protein" would have bound substrates (peptides, phosphate, nucleosides, RNA 'monomers') and condensed them to a reaction product that remained bound until after

neg: Fumarase deficiency Krebs cycle or tricarboxylic acid cycle, the main enzymatic pathway of cellular aerobic respiration. The condition is an autosomal recessive disorder, and it is therefore usually necessary for an affected individual to receive the mutant allele from both parents. A number of children diagnosed with the disorder have been born to parents who were first cousins. It can also be associated with uniparental isodisomy. There is a deficiency of malate in patients because fumarase enzyme can't convert fumarate into it therefore treatment is with oral malic acid which will allow the krebs cycle to continue, and eventually make ATP. Fumarase

neg: Geobacillus thermoglucosidasius Geobacillus thermoglucosidasius Geobacillus thermoglucosidasius is a thermophilic gram-positive bacterium, and a member of the "Firmicutes" phylum. It was first isolated from soil in Japan in 1983. The species name "thermoglucosidasius" comes from the words "therme" denoting heat, and "glucosidasius" denoting starch-hydrolyzing glucosidase activity. "G. thermoglucosidasius" is gram-positive (bacterium that retains Crystal violet dye during gram-staining) and facultatively anaerobic(produces ATP by aerobic respiration if oxygen is present, but capable of switching to fermentation or anaerobic respiration if oxygen is absent). "G. thermoglucosidasius" is classified as a thermophile as optimal growth occurs at 60 °C (140 °F), although strains have demonstrated ability

neg: Anaerobic organism use anaerobic respiration. Aerotolerant organisms are strictly fermentative. In the presence of oxygen, facultative anaerobes use aerobic respiration; without oxygen, some of them ferment; some use anaerobic respiration. There are many anaerobic fermentative reactions. Fermentative anaerobic organisms mostly use the lactic acid fermentation pathway: The energy released in this equation is approximately 150 kJ per mol, which is conserved in regenerating two ATP from ADP per glucose. This is only 5% of the energy per sugar molecule that the typical aerobic reaction generates. Plants and fungi (e.g., yeasts) in general use alcohol (ethanol) fermentation when oxygen becomes limiting: The energy

neg: Cellular respiration NADH are produced when the pyruvate are oxidized. The overall reaction can be expressed this way: Starting with glucose, 1 ATP is used to donate a phosphate to glucose to produce glucose 6-phosphate. Glycogen can be converted into glucose 6-phosphate as well with the help of glycogen phosphorylase. During energy metabolism, glucose 6-phosphate becomes fructose 6-phosphate. An additional ATP is used to phosphorylate fructose 6-phosphate into fructose 1,6-disphosphate by the help of phosphofructokinase. Fructose 1,6-diphosphate then splits into two phosphorylated molecules with three carbon chains which later degrades into pyruvate. Glycolysis can be literally translated as "sugar splitting". Pyruvate is

neg: Salt marsh dieback waterlogged soils contain many reduced molecules, which can induce the accumulation of sulfide and other toxic compounds. Current studies suggest that increased waterlogging is caused by sea level rise, a possible effect of global warming, which has many natural and anthropologic causes of its own. Salt marsh dieback results in the death of marsh-specific plants and the erosion of the landscape. One of the causes of waterlogging is the reduced aerobic respiration by the roots of "S. alterniflora". It occurs mainly in the inland zones, though the streamside plants show partial anaerobic respiration. Aerobic respiration takes sugars and oxygen to

neg: Anaerobic respiration being oxygen (in aerobic respiration) or another chemical substance (in anaerobic respiration). A proton motive force drives protons down the gradient (across the membrane) through the proton channel of ATP synthase. The resulting current drives ATP synthesis from ADP and inorganic phosphate. Fermentation, in contrast, does not utilize an electrochemical gradient. Fermentation instead only uses substrate-level phosphorylation to produce ATP. The electron acceptor NAD+ is regenerated from NADH formed in oxidative steps of the fermentation pathway by the reduction of oxidized compounds. These oxidized compounds are often formed during the fermentation pathway itself, but may also be external. For example,

neg: Anaerobic respiration molecule. Therefore, generally speaking, anaerobic respiration is less efficient than aerobic. There are two important microbial methane formation pathways, through carbonate reduction (respiration), and acetate fermentation. Cellular respiration (both aerobic and anaerobic) utilizes highly reduced chemical compounds such as NADH and FADH2 (for example produced during glycolysis and the citric acid cycle) to establish an electrochemical gradient (often a proton gradient) across a membrane, resulting in an electrical potential or ion concentration difference across the membrane. The reduced chemical compounds are oxidized by a series of respiratory integral membrane proteins with sequentially increasing reduction potentials with the final electron acceptor

neg: Nucleoside triphosphate both cellular respiration and photosynthesis by ATP synthase. ATP synthase couples the synthesis of ATP from ADP and phosphate with an electrochemical gradient generated by the pumping of protons through either the inner mitochondrial membrane (cellular respiration) or the thylakoid membrane (photosynthesis). This electrochemical gradient is necessary because the formation of ATP is energetically unfavourable. The hydrolysis of ATP to ADP and Pi proceeds as follows: This reaction is energetically favourable and releases 30.5 kJ/mol of energy. In the cell, this reaction is often coupled with unfavourable reactions to provide the energy for them to proceed. GTP is occasionally used

neg: Crista Crista A crista (; plural cristae) is a fold in the inner membrane of a mitochondrion. The name is from the Latin for "crest" or "plume", and it gives the inner membrane its characteristic wrinkled shape, providing a large amount of surface area for chemical reactions to occur on. This aids aerobic cellular respiration, because the mitochondrion requires oxygen. Cristae are studded with proteins, including ATP synthase and a variety of cytochromes. With the discovery of the dual-membrane nature of mitochondria, the pioneers of mitochondrial ultrastructural research proposed different models for the organization of the mitochondrial inner membrane. Three models

neg: Vitamin K with an excess of electrons (also called an electron donor) such as lactate, formate, or NADH, with the help of an enzyme, passes two electrons to menaquinone. The menaquinone, with the help of another enzyme, then transfers these two electrons to a suitable oxidant, such fumarate or nitrate (also called an electron acceptor). Adding two electrons to fumarate or nitrate converts the molecule to succinate or nitrite plus water, respectively. Some of these reactions generate a cellular energy source, ATP, in a manner similar to eukaryotic cell aerobic respiration, except the final electron acceptor is not molecular oxygen, but fumarate

neg: Bioenergetics the homeostatic control of energy balance – the difference between energy obtained through food consumption and energy expenditure – in living systems. Bioenergetics Bioenergetics is a field in biochemistry and cell biology that concerns energy flow through living systems. This is an active area of biological research that includes the study of the transformation of energy in living organisms and the study of thousands of different cellular processes such as cellular respiration and the many other metabolic and enzymatic processes that lead to production and utilization of energy in forms such as adenosine triphosphate (ATP) molecules. That is, the goal

neg: Bioenergetics Bioenergetics Bioenergetics is a field in biochemistry and cell biology that concerns energy flow through living systems. This is an active area of biological research that includes the study of the transformation of energy in living organisms and the study of thousands of different cellular processes such as cellular respiration and the many other metabolic and enzymatic processes that lead to production and utilization of energy in forms such as adenosine triphosphate (ATP) molecules. That is, the goal of bioenergetics is to describe how living organisms acquire and transform energy in order to perform biological work. The study of metabolic

neg: Carbohydrate metabolism Carbohydrate metabolism Various biochemical processes responsible for the metabolic formation, breakdown, and interconversion of carbohydrates in living organisms. Carbohydrates are central to many essential metabolic pathways. Plants synthesize carbohydrates from carbon dioxide and water through photosynthesis, allowing them to store energy absorbed from sunlight internally. When animals and fungi consume plants, they use cellular respiration to break down these stored carbohydrates to make energy available to cells. Both animals and plants temporarily store the released energy in the form of high energy molecules, such as ATP, for use in various cellular processes. Although humans consume a variety of carbohydrates, digestion

neg: Basal metabolic rate total energy requirement during a two-hour aerobic training session. This process could severely degrade the protein structures needed to maintain survival such as contractile properties of proteins in the heart, cellular mitochondria, myoglobin storage, and metabolic enzymes within muscles. The oxidative system (aerobic) is the primary source of ATP supplied to the body at rest and during low intensity activities and uses primarily carbohydrates and fats as substrates. Protein is not normally metabolized significantly, except during long term starvation and long bouts of exercise (greater than 90 minutes.) At rest approximately 70% of the ATP produced is derived from fats

neg: Terrestrial biological carbon cycle plants. Carbon storage in the biosphere is influenced by a number of processes on different time-scales: while carbon uptake through autotrophic respiration follows a diurnal and seasonal cycle, carbon can be stored in the terrestrial biosphere for up to several centuries, e.g. in wood or soil. Most carbon leaves the terrestrial biosphere through respiration. When oxygen is present, aerobic respiration occurs, producing carbon dioxide. If oxygen is not present, e.g. as is the case in marshes or in animals' digestive tracts, anaerobic respiration can occur, which produces methane. About half of the gross primary production is respired by plants directly

neg: Chemiosmosis Chemiosmosis Chemiosmosis is the movement of ions across a semipermeable membrane, down their electrochemical gradient. An example of this would be the generation of adenosine triphosphate (ATP) by the movement of hydrogen ions (H) across a membrane during cellular respiration or photosynthesis. Hydrogen ions, or protons, will diffuse from an area of high proton concentration to an area of lower proton concentration, and an electrochemical concentration gradient of protons across a membrane can be harnessed to make ATP. This process is related to osmosis, the diffusion of water across a membrane, which is why it is called "chemiosmosis". ATP synthase

neg: Yeast at the Centennial Exposition in 1876 in Philadelphia, where Charles L. Fleischmann exhibited the product and a process to use it, as well as serving the resultant baked bread. Yeasts are chemoorganotrophs, as they use organic compounds as a source of energy and do not require sunlight to grow. Carbon is obtained mostly from hexose sugars, such as glucose and fructose, or disaccharides such as sucrose and maltose. Some species can metabolize pentose sugars such as ribose, alcohols, and organic acids. Yeast species either require oxygen for aerobic cellular respiration (obligate aerobes) or are anaerobic, but also have aerobic methods

neg: Phosphofructokinase 1 is by phosphorylating the enzyme at the serine residues. The HSV-1 induced glycolysis increases ATP content, which is critical for the virus’s replication. Phosphofructokinase 1 Phosphofructokinase-1 (PFK-1) is one of the most important regulatory enzymes () of glycolysis. It is an allosteric enzyme made of 4 subunits and controlled by many activators and inhibitors. PFK-1 catalyzes the important "committed" step of glycolysis, the conversion of fructose 6-phosphate and ATP to fructose 1,6-bisphosphate and ADP. Glycolysis is the foundation for respiration, both anaerobic and aerobic. Because phosphofructokinase (PFK) catalyzes the ATP-dependent phosphorylation to convert fructose-6-phosphate into fructose 1,6-bisphosphate and ADP, it

neg: Flutamide of action of flutamide-induced hepatotoxicity is thought to be due to mitochondrial toxicity. Specifically, flutamide and particularly its major metabolite hydroxyflutamide inhibit enzymes in the mitochondrial electron transport chain in hepatocytes, including respiratory complexes I (), II (succinate dehydrogenase), and V (ATP synthase), and thereby reduce cellular respiration via ATP depletion and hence decrease cell survival. Inhibition of taurocholate (a bile acid) efflux has also been implicated in flutamide-induced hepatotoxicity. In contrast to flutamide and hydroxyflutamide, which severely compromise hepatocyte cellular respiration "in vitro", bicalutamide does not significantly do so at the same concentrations and is regarded as non-mitotoxic. It

neg: Escherichia coli ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation or anaerobic respiration if oxygen is absent) and nonsporulating bacterium. Cells are typically rod-shaped, and are about 2.0 μm long and 0.25–1.0 μm in diameter, with a cell volume of 0.6–0.7 μm. "E. coli" stains Gram-negative because its cell wall is composed of a thin peptidoglycan layer and an outer membrane. During the staining process, "E. coli" picks up the color of the counterstain safranin and stains pink. The outer membrane surrounding the cell wall provides a barrier to certain antibiotics such that "E. coli"

neg: Boring Billion in terms of the advantage gained by the host cell due to the greater energy production available through aerobic respiration (32 net ATP vs. 2 net for glycolysis). However, this hypothesis has several limitations. No known organism exports ATP to its environment, making it unlikely that a bacterium would begin doing so to its host. In addition, some eukaryotes possess mitochondria-derived organelles called hydrogenosomes which perform a type of anaerobic respiration, suggesting an adaptation to an anoxic environment. An alternative explanation known as the Hydrogen Hypothesis suggests that the unique conditions of the Canfield Ocean may have exerted a positive