query: how many atp are produced from one molecule of glucose during aerobic cellular respiration

pos: 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: 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: 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 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: 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

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: 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: 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 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 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: 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

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: Pasteur effect in the glycolysis pathway. The Pasteur effect will only occur if glucose concentrations are low (<2 g/L) and if other nutrients, mostly nitrogen, are limited. From the standpoint of ATP production then, it is advantageous for yeast to utilize the citric acid cycle in the presence of oxygen, as more ATP is produced from less glucose; however, Boulton et al. (1996) have maintained that yeast will follow the anaerobic, rather than aerobic, fermentative pathway if glucose is not limited, in that respiration, although capable of producing more ATP than glycolysis per molecule of glucose, also requires more energy in terms

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: 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 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: 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: 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: 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: Cellular respiration to the Krebs cycle. However, if oxygen is not present, fermentation of the pyruvate molecule will occur. In the presence of oxygen, when acetyl-CoA is produced, the molecule then enters the citric acid cycle (Krebs cycle) inside the mitochondrial matrix, and is oxidized to CO while at the same time reducing NAD to NADH. NADH can be used by the electron transport chain to create further ATP as part of oxidative phosphorylation. To fully oxidize the equivalent of one glucose molecule, two acetyl-CoA must be metabolized by the Krebs cycle. Two waste products, HO and CO, are created during this

neg: Cellular respiration ATP. In eukaryotes, oxidative phosphorylation occurs in the mitochondrial cristae. It comprises the electron transport chain that establishes a proton gradient (chemiosmotic potential) across the boundary of inner membrane by oxidizing the NADH produced from the Krebs cycle. ATP is synthesized by the ATP synthase enzyme when the chemiosmotic gradient is used to drive the phosphorylation of ADP. The electrons are finally transferred to exogenous oxygen and, with the addition of two protons, water is formed. The table below describes the reactions involved when one glucose molecule is fully oxidized into carbon dioxide. It is assumed that all the reduced

neg: 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

neg: Muscle of fat, which are used for energy during aerobic exercise. The aerobic energy systems take longer to produce the ATP and reach peak efficiency, and requires many more biochemical steps, but produces significantly more ATP than anaerobic glycolysis. Cardiac muscle on the other hand, can readily consume any of the three macronutrients (protein, glucose and fat) aerobically without a 'warm up' period and always extracts the maximum ATP yield from any molecule involved. The heart, liver and red blood cells will also consume lactic acid produced and excreted by skeletal muscles during exercise. At rest, skeletal muscle consumes 54.4 kJ/kg

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: 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: 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: 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

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: 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 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: Mixed acid fermentation energy in comparison to respiration. Mixed acid fermentation in "E. coli" occurs in two stages. These stages are outlined by the biological database for "E. coli", EcoCyc. The first of these two stages is a glycolysis reaction. Under anaerobic conditions, a glycolysis reaction takes place where glucose is converted into pyruvate: glucose → 2 pyruvate There is a net production of 2 ATP and 2 NADH molecules per molecule of glucose converted. ATP is generated by substrate-level phosphorylation. NADH is formed from the reduction of NAD. In the second stage, pyruvate produced by glycolysis is converted to one or more

neg: 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

neg: 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

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: 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: 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

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: 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: 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

neg: Carbohydrate metabolism glycolysis pathway and is later cleaved into glyceraldehyde and dihydroxyacetone phosphate. Lactose, or milk sugar, consists of one molecule of glucose and one molecule of galactose. After separation from glucose, galactose travels to the liver for conversion to glucose. Galactokinase uses one molecule of ATP to phosphorylate galactose. The phosphorylated galactose is then converted to glucose-1-phosphate, and then eventually glucose-6-phosphate, which can be broken down in glycolysis. Many steps of carbohydrate metabolism allow the cells to access energy, and store it more transiently in ATP. The cofactors NAD and FAD are sometimes reduced during this process to form NADH and

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: 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: Carbohydrate metabolism breaks down complex carbohydrates into a few simple monomers (monosaccharides) for metabolism: glucose, fructose, and galactose. Glucose constitutes about 80% of the products, and is the primary structure that is distributed to cells in the tissues, where it is broken down or stored as glycogen. In aerobic respiration, the main form of cellular respiration used by humans, glucose and oxygen are metabolized to release energy, with carbon dioxide and water as byproducts. Most of the fructose and galactose travel to the liver, where they can be converted to glucose. Some simple carbohydrates have their own enzymatic oxidation pathways, as do

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: 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: 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: 1,3-Bisphosphoglyceric acid of 1,3BPG is important in respiration as it assists in the formation of ATP. The molecule of ATP created during the following reaction is the first molecule produced during respiration. The reaction occurs as follows; The transfer of an inorganic phosphate from the carboxyl group on 1,3BPG to ADP to form ATP is reversible due to a low ΔG. This is as a result of one acyl phosphate bond being cleaved whilst another is created. This reaction is not naturally spontaneous and requires the presence of a catalyst. This role is performed by the enzyme phosphoglycerate kinase. During the reaction

neg: 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

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: Glucose the formation of lactate, the end product of fermentation in mammals, even in the presence of oxygen. This effect is called the Warburg effect. For the increased uptake of glucose in tumors various SGLT and GLUT are overly produced. In yeast, ethanol is fermented at high glucose concentrations, even in the presence of oxygen (which normally leads to respiration but not to fermentation). This effect is called the Crabtree effect. Glucose is a ubiquitous fuel in biology. It is used as an energy source in organisms, from bacteria to humans, through either aerobic respiration, anaerobic respiration (in bacteria), or fermentation.

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: Microbial metabolism glycolysis). As oxygen is not required, fermentative organisms are anaerobic. Many organisms can use fermentation under anaerobic conditions and aerobic respiration when oxygen is present. These organisms are facultative anaerobes. To avoid the overproduction of NADH, obligately fermentative organisms usually do not have a complete citric acid cycle. Instead of using an ATP synthase as in respiration, ATP in fermentative organisms is produced by substrate-level phosphorylation where a phosphate group is transferred from a high-energy organic compound to ADP to form ATP. As a result of the need to produce high energy phosphate-containing organic compounds (generally in the form of

neg: Aerobic fermentation yeast species' tolerance for ethanol and allowed Crabtree-positive species to consume the ethanol they produced after depleting sugars. However, Adh2 and consumption of ethanol is not essential for aerobic fermentation. "Sch. pombe" and other Crabtree positive species do not have the "ADH2" gene and consumes ethanol very poorly. In Crabtree-negative species, respiration related genes are highly expressed in the presence of oxygen. However, when "S. cerevisiae" is grown on glucose in aerobic conditions, respiration-related gene expression is repressed. Mitochondrial ribosomal proteins expression is only induced under environmental stress conditions, specifically low glucose availability. Genes involving mitochondrial energy generation and phosphorylation

neg: Citric acid cycle that produces ATP (ADP-forming succinyl-CoA synthetase). Several of the enzymes in the cycle may be loosely associated in a multienzyme protein complex within the mitochondrial matrix. The GTP that is formed by GDP-forming succinyl-CoA synthetase may be utilized by nucleoside-diphosphate kinase to form ATP (the catalyzed reaction is GTP + ADP → GDP + ATP). Products of the first turn of the cycle are one GTP (or ATP), three NADH, one QHand two CO. Because two acetyl-CoA molecules are produced from each glucose molecule, two cycles are required per glucose molecule. Therefore, at the end of two cycles, the products

neg: Carbon dioxide ethanol, also known as alcohol, as follows: All aerobic organisms produce when they oxidize carbohydrates, fatty acids, and proteins. The large number of reactions involved are exceedingly complex and not described easily. Refer to (cellular respiration, anaerobic respiration and photosynthesis). The equation for the respiration of glucose and other monosaccharides is: Anaerobic organisms decompose organic material producing methane and carbon dioxide together with traces of other compounds. Regardless of the type of organic material, the production of gases follows well defined kinetic pattern. Carbon dioxide comprises about 40–45% of the gas that emanates from decomposition in landfills (termed "landfill gas").

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: 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: 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: 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: 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: ATP synthase ATP synthase ATP synthase is an enzyme that creates the energy storage molecule adenosine triphosphate (ATP). ATP is the most commonly used "energy currency" of cells for all organisms. It is formed from adenosine diphosphate (ADP) and inorganic phosphate (P). The overall reaction catalyzed by ATP synthase is: The formation of ATP from ADP and P is energetically unfavorable and would normally proceed in the reverse direction. In order to drive this reaction forward, ATP synthase couples ATP synthesis during cellular respiration to an electrochemical gradient created by the difference in proton (H) concentration across the mitochondrial membrane in eukaryotes

neg: Aerobic organism Aerotolerant organisms must continue fermentation in the presence of oxygen. A good example is the oxidation of glucose (a monosaccharide) in aerobic respiration. Oxygen is used during the oxidation of glucose and water is produced. This equation is a summary of what happens in three series of biochemical reactions: glycolysis, the Krebs cycle, and oxidative phosphorylation. Aerobic organism An aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment. In contrast, an anaerobic organism (anaerobe) is any organism that does not require oxygen for growth. Some anaerobes react negatively or even die if oxygen

neg: Aerobic fermentation due to the capacity for a high glycolytic flux and the high glucose concentrations of their natural environment. The mechanism for repression of respiration in these conditions is not yet known. A couple "Escherichia coli" mutant strains have been bioengineered to ferment glucose under aerobic conditions. One group developed the ECOM3 ("E. coli" cytochrome oxidase mutant) strain by removing three terminal cytochrome oxidases (cydAB, cyoABCD, and cbdAB) to reduce oxygen uptake. After 60 days of adaptive evolution on glucose media, the strain displayed a mixed phenotype. In aerobic conditions, some populations' fermentation solely produced lactate, while others did mixed-acid fermentation.

neg: Allosteric regulation deemed inactive. This causes glycolysis to cease when ATP levels are high, thus conserving the body's glucose and maintaining balanced levels of cellular ATP. In this way, ATP serves as a negative allosteric modulator for PFK, despite the fact that it is also a substrate of the enzyme. A homotropic allosteric modulator is a substrate for its target enzyme, as well as a regulatory molecule of the enzyme's activity. It is typically an activator of the enzyme. For example, O and CO are homotropic allosteric modulators of hemoglobin. Likewise, in IMP/GMP specific 5' nucleotidase, binding of one GMP molecule to

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: 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

neg: Diauxie is plenty of glucose and oxygen available, the yeast cells prefer glucose fermentation to aerobic respiration even though aerobic respiration is the more efficient pathway to grow on glucose. Contrary to the more commonly invoked Pasteur effect, this phenomenon of preferring the faster growth supporting fermentation is closer to the Warburg effect observed in faster growing tumors. The intracellular genetic regulatory mechanisms have evolved to enforce this choice, as fermentation provides a faster growth rate for the yeast cells than the aerobic respiration of glucose. After glucose is depleted, the fermentative product ethanol is oxidised in a noticeably slower second

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: Malolactic fermentation inoculation (such as "wild" ferments versus an inoculation of cultured "O. oeni"). The genus "Oenococcus" has one main member involved in winemaking, "O. oeni", once known as "Leuconostoc oeni". Despite having the name "Oenococcus", under the microscope, the bacterium has a bacillus (shape) rod shape. The bacteria is a Gram-positive, facultative anaerobe that can utilize some oxygen for aerobic respiration but usually produces cellular energy through fermentation. "O. oeni" is a heterofermenter that create multiple end products from the use of glucose with D-lactic acid and carbon dioxide being produced in roughly equal amounts to either ethanol or acetate. In

neg: Glucose Glucose is the human body's key source of energy, through aerobic respiration, providing about 3.75 kilocalories (16 kilojoules) of food energy per gram. Breakdown of carbohydrates (e.g., starch) yields mono- and disaccharides, most of which is glucose. Through glycolysis and later in the reactions of the citric acid cycle and oxidative phosphorylation, glucose is oxidized to eventually form carbon dioxide and water, yielding energy mostly in the form of ATP. The insulin reaction, and other mechanisms, regulate the concentration of glucose in the blood. The physiological caloric value of glucose, depending on the source, is 16.2 kilojoules per gram and

neg: Biochemistry pathway. In aerobic cells with sufficient oxygen, as in most human cells, the pyruvate is further metabolized. It is irreversibly converted to acetyl-CoA, giving off one carbon atom as the waste product carbon dioxide, generating another reducing equivalent as NADH. The two molecules acetyl-CoA (from one molecule of glucose) then enter the citric acid cycle, producing two more molecules of ATP, six more NADH molecules and two reduced (ubi)quinones (via FADH as enzyme-bound cofactor), and releasing the remaining carbon atoms as carbon dioxide. The produced NADH and quinol molecules then feed into the enzyme complexes of the respiratory chain, an

neg: 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

neg: Lactic acid production from neutral glucose that generates H: Although the reaction glucose → 2 lactate + 2 H releases two H when viewed on its own, the H are absorbed in the production of ATP. On the other hand, the absorbed acidity is released during subsequent hydrolysis of ATP: ATP + HO → ADP + + H. So once the use of the ATP is included, the overall reaction is The generation of CO during respiration also causes an increase in [H]. Although glucose is usually assumed to be the main energy source for living tissues, there are some indications that

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: Anaerobic glycolysis Anaerobic glycolysis Anaerobic glycolysis is the transformation of glucose to lactate when limited amounts of oxygen (O) are available. Anaerobic glycolysis is only an effective means of energy production during short, intense exercise, providing energy for a period ranging from 10 seconds to 2 minutes. The anaerobic glycolysis (lactic acid) system is dominant from about 10–30 seconds during a maximal effort. It replenishes very quickly over this period and produces 2 ATP molecules per glucose molecule or about 5% of glucose's energy potential (38 ATP molecules). The speed at which ATP is produced is about 100 times that of oxidative

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: Aeromonas salmonicida diffusible pigment within two to four days. Most typical strains are morphologically and biochemically homogenous with a few exceptions. Some of these exceptions include a distinguishable variation in pigment production, the bacterium's ability to ferment selected sugars, and Voges-Proskauer assay results. "A. salmonicida" is a facultative anaerobe, which means it is capable of making ATP by aerobic respiration if oxygen is present, but is also capable of switching to fermentation when oxygen is not present. It does not ferment sucrose or lactose, using glucose in this pathway, instead; glucose fermentation creates gas. The bacterium grows optimally at temperatures between 22

neg: Glucokinase cells, the beta cells of the pancreatic islets are the most-studied and best-understood. It is likely that many of the regulatory relationships discovered in the beta cells will also exist in the other neuroendocrine tissues with glucokinase. In islet beta cells, glucokinase activity serves as a principal control for the secretion of insulin in response to rising levels of blood glucose. As G6P is consumed, increasing amounts of ATP initiate a series of processes that result in release of insulin. One of the immediate consequences of increased cellular respiration is a rise in the NADH and NADPH concentrations (collectively referred

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: Pasteur effect converted to acetyl CoA that can be used in the citric acid cycle, which increases the efficiency to 36 moles of ATP per mole of glucose. Therefore, about 16 times as much glucose must be consumed anaerobically as aerobically to yield the same amount of ATP. Under anaerobic conditions, the rate of glucose metabolism is faster, but the amount of ATP produced (as already mentioned) is smaller. When exposed to aerobic conditions, the ATP and Citrate production increases and the rate of glycolysis slows, because the ATP and citrate produced act as allosteric inhibitors for phosphofructokinase 1, the third enzyme

neg: Amphibolic one ATP molecule and a yield of 2 ATP and 2 pyruvate molecules also 1 NADH .This show the difference between the glycolytic used by humans and this pathway,that in this pathway, it require an investment of one ATP to yield a 2ATP and 2 pyruvate as a net of only one NADPH produced and one ATP result (from substrate level phosphorylation ), and the other pathway involve an investment of 2 ATP molecules to yield 4 ATP and 2 pyruvate molecules per glucose as a net of 2 ATP molecule . The cell determine whether the amphibolic function act

neg: Reducing agent "reduced" by) reducers. In their pre-reaction states, reducers have more electrons (that is, they are by themselves reduced) and oxidizers have fewer electrons (that is, they are by themselves oxidized). A reducing agent typically is in one of its lower possible oxidation states and is known as the electron donor. Examples of reducing agents include the earth metals, formic acid, and sulfite compounds. For example, consider the overall reaction for aerobic cellular respiration: The oxygen (O) is being reduced, so it is the oxidizing agent. The glucose (CHO) is being oxidized, so it is the reducing agent. In organic chemistry,

neg: Sulcia muelleri they are transferred vertically from the host to their host's offspring. Evidence suggests that "Sulcia muelleri" utilizes aerobic respiration. ATP is synthesized by way of a cytochrome c oxidase catalyzed termination. The cytochrome is of the type "cbb-3". The electron donor for "Sulcia muelleri" is implied to be some carbon source retrieved from the sap-feeding diet of its host. Some examples are glutamate, malate and glucose; all of which are found in xylem sap. The symbiont harvests reducing power in the form of NADH. The analysis of "Sulcia muelleri, strand GWSS's" reduced genome suggests that a proportionate amount of the

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: 1,3-Bisphosphoglyceric acid phosphoglycerate kinase undergoes a substrate induced conformational change similar to another metabolic enzyme called hexokinase. Because two molecules of glyceraldehyde-3-phosphate are formed during glycolysis from one molecule of glucose, 1,3BPG can be said to responsible for two of the ten molecules of ATP produced during the entire process. Glycolysis also uses two molecules of ATP in its initial stages as a committed and irreversible step. For this reason glycolysis is not reversible and has a net produce of 2 molecules of ATP and two of NADH. The two molecules of NADH themselves go on to produce approximately 3 molecules of

neg: Fluid balance correct the imbalance. Fluid can leave the body in many ways. Fluid can enter the body as preformed water, ingested food and drink and to a lesser extent as metabolic water which is produced as a by-product of aerobic respiration (cellular respiration) and dehydration synthesis. A constant supply is needed to replenish the fluids lost through normal physiological activities, such as respiration, sweating and urination. Water generated from the biochemical metabolism of nutrients provides a significant proportion of the daily water requirements for some arthropods and desert animals, but provides only a small fraction of a human's necessary intake. In

neg: Oxygen production of the water molecule) is released into the atmosphere. Oxygen is used in mitochondria to generate ATP during oxidative phosphorylation. The reaction for aerobic respiration is essentially the reverse of photosynthesis and is simplified as: In vertebrates, diffuses through membranes in the lungs and into red blood cells. Hemoglobin binds , changing color from bluish red to bright red ( is released from another part of hemoglobin through the Bohr effect). Other animals use hemocyanin (molluscs and some arthropods) or hemerythrin (spiders and lobsters). A liter of blood can dissolve 200 cm of . Until the discovery of anaerobic

neg: Malate-aspartate shuttle ATPs produced in glycolysis (3/NADH), ultimately resulting in a net gain of 38 ATP molecules per molecule of glucose metabolized. Compare this to the glycerol 3-phosphate shuttle, which reduces FAD to produce FADH, donates electrons to the quinone pool in the electron transport chain, and is capable of generating only 2 ATPs per NADH generated in glycolysis (ultimately resulting in a net gain of 36 ATPs per glucose metabolized). (These ATP numbers are prechemiosmotic, and should be reduced in light of the work of Mitchell and many others. Each NADH produced only 2.5 ATPs, and each FADH produces only 1.5

neg: Glycerol kinase deficiency it into the energy rich molecule pyruvate. Inside the overall reaction there lie many steps that need to be followed in order for the original glucose molecule to be transformed into pyruvate. The glucose first gathers a phosphate group from an ATP molecule in order to become glucose-6-phosphate. It is then changed into fructose 6-phosphate, with the assistance of phosphoglucose isomerase, which is then changed into fructose 1,6-biphosphate when the fructose molecule receives a phosphate group from another ATP. The next step in the chain is crucial for cells in order to make more energy than they expend through the

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: 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: Photosynthetic efficiency enzymes) from high oxygen concentrations produced by photosynthesis, in that O is evolved during the day, and allowed to dissipate then, while at night atmospheric CO is taken up and stored as malic or other acids. During the day, CAM plants close stomata and use stored acids as carbon sources for sugar, etc. production. The C3 pathway requires 18 ATP for the synthesis of one molecule of glucose while the C4 pathway requires 20 ATP. Despite this reduced ATP efficiency, C4 is an evolutionary advancement, adapted to areas of high levels of light, where the reduced ATP efficiency is more

neg: Aerobic fermentation One of the hallmarks of cancer is altered metabolism or deregulating cellular energetics. Cancers cells often have reprogrammed their glucose metabolism to perform lactic acid fermentation, in the presence of oxygen, rather than send the pyruvate made through glycolysis to the mitochondria. This is referred to as the Warburg effect, and is associated with high consumption of glucose and a high rate of glycolysis. ATP production in these cancer cells is often only through the process of glycolysis and pyruvate is broken down by the fermentation process in the cell's cytoplasm. This phenomenon is often seen as counterintuitive, since cancer

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: 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: 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: Active transport is then used to power the active transport of a second ion or molecule against its gradient. In bacteria and small yeast cells, a commonly cotransported ion is hydrogen. Hydrogen pumps are also used to create an electrochemical gradient to carry out processes within cells such as in the electron transport chain, an important function of cellular respiration that happens in the mitochondrion of the cell. In August 1960, in Prague, Robert K. Crane presented for the first time his discovery of the sodium-glucose cotransport as the mechanism for intestinal glucose absorption. Crane's discovery of cotransport was the first ever

neg: Substrate-level phosphorylation substrate-level phosphorylation. The second substrate-level phosphorylation occurs by dephosphorylating phosphoenolpyruvate, catalyzed by pyruvate kinase, producing pyruvate and ATP. During the preparatory phase, each 6-carbon glucose molecule is broken into two 3-carbon molecules. Thus, in glycolysis dephosphorylation results in the production of 4 ATP. However, the prior preparatory phase consumes 2 ATP, so the net yield in glycolysis is 2 ATP. 2 molecules of NADH are also produced and can be used in oxidative phosphorylation to generate more ATP. ATP can be generated by substrate-level phosphorylation in mitochondria in a pathway that is independent from the proton motive force. In the

neg: Cell (biology) anabolism, in which the cell uses energy and reducing power to construct complex molecules and perform other biological functions. Complex sugars consumed by the organism can be broken down into simpler sugar molecules called monosaccharides such as glucose. Once inside the cell, glucose is broken down to make adenosine triphosphate (ATP), a molecule that possesses readily available energy, through two different pathways. Cells are capable of synthesizing new proteins, which are essential for the modulation and maintenance of cellular activities. This process involves the formation of new protein molecules from amino acid building blocks based on information encoded in DNA/RNA.

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