Citric Acid Cycle

The krebs cycle is the second step in aerobic respiration of cells, which takes place in the matrix of the mitochondria of eukaryotic cells. This process is to oxidize pyruvate.

In contrast, there are four metabolic stages happened in cellular respiration, which are the glycolysis, the citric acid cycle, and the oxidative phosphorylation. Glycolysis occurs in the cytoplasm, in which catabolism is begun by breaking down glucose into two molecules of pyruvate. Two molecules of ATP are produced too. Some of they either enter the citric acid cycle (Krebs cycle) or the electron transport chain, or go into lactic acid cycle if there is not enough oxygen, which produces lactic acid. The citric acid cycle occurs in the mitochondrial matrix, which completes the breakdown of glucose by oxidizing a derivative of pyruvate into carbon dioxide. The citric acid cycle produced some more ATPs and other molecules called NADPH and FADPH. After this, electrons are passed to the electron transport chain through

There are two types of cellular respiration, aerobic and anaerobic. Aerobic respiration occurs when there is oxygen present and in the mitochondria (in eukaryotic cells) and the cytoplasm (in prokaryotic cells). Aerobic respiration requires oxygen; it proceeds through the Krebs cycle. The Krebs cycle is a cycle of producing carbon dioxide and water as waste products, and converting ADP to thirty-four ATPs. Anaerobic respiration is known as a process called fermentation. It occurs in the cytoplasm and molecules do not enter the mitochondria for further breakdown. This process helps to produce alcohol in yeast and plants, and lactate in animals. Only two ATPs are produced through this process. In yeast fermentation is used to make beer, wine, and whiskey.

Aerobic respiration happens only when oxygen is presented in the cell. Aerobic respiration starts with pyruvate crossing into the mitochondria. When it passes through, a Coenzyme A will attach to it producing Acetyl CoA, CO2, and NADH. Acetyl CoA will enter into the Krebs cycle. In the Krebs cycle Acetyl CoA will bound with Oxaloacetic Acid (OAA), a four carbon molecule, producing the six carbon molecule, Citric Acid. Citric Acid will reorganize into Isocitrate. This will lose a CO2 and make a NADH turning itself into alpha ketoglutarate, a five carbon molecule. Alpha ketoglutarate will turn into an unstable four carbon molecule, which attaches to CoA making succinyl CoA. During that process a CO2 and NADH is made. An ATP is made when CoA leaves and creates Succinate. This molecule is turned into Fumarate, creating two FADH2 in the process. Then Fumarate is turned into Malate then into OAA making two NADH. Only two ATP is produced in Krebs cycle but the resulting NADHs and FADH2s are passed through an electron transport chain and ATP synthase. When the molecules passes through that cycle a total of 28 ATP molecules are produced. In all aerobic respiration produces 32 ATP and waste products of H2O and

The citric acid cycle, also called the Krebs cycle or the tricarboxylic acid, TCA, cycle, a series of chemical reactions that generates energy from the oxidation of acetate into chemical energy and carbon dioxide in the form of ATP. It also provides NADH, which is a reducing agent that is very common in biochemical reactions. This cycle is constantly supplied with new carbon. This comes in from acetyl-CoA, which starts the entire process of the citric acid cycle. The first step of the citric acid cycle is the aldol condensation of oxaloacetate and acetyl-CoA and water with the enzyme citrate synthase in order to form citrate and CoA-SH. The next step is the dehydration of citrate with the enzyme aconitase in order to form cis-aconitate and water. Then comes the hydration of cis-Aconitate and water with the enzyme aconitase in order to form isocitrate. The next is the oxidation of isocitrate and NAD+ with the enzyme isocitrate dehydrogenase in order to form oxalosuccinate and NADH and H+. Then, there is the decarboxylation of oxalosuccinate with the enzyme isocitrate dehydrogenase in order to form alpha-ketoglutarate and carbon dioxide. Next, there is the oxidative decarboxylation of alpha-ketoglutarate and NAD+ and CoA-SH with the enzyme alpha-ketoglutarate dehydrogenase in order to form succinyl-CoA and NADH and H+ and carbon dioxide. The next step is the substrate-level phosphorylation of succinyl-CoA and GDP and Pi with the enzyme succinyl-CoA synthetase in order to form succinate and CoA-SH and GTP. Then, there is the oxidation of succinate and ubiquinone with the enzyme succinate dehydrogenase in order to form fumarate and ubiquinol. Next, is the hydration of fumarate and water with the enzyme fumarase in order to form L-malate. The final step is the oxidation of L-malate and NAD+ with the enzyme malate dehydrogenase in order to form oxaloacetate and NADH and H+. Two cycles are required for every single glucose molecule because two acetyl Co-A molecules

cycle produces two ATP molecules at a cost of six ATP molecules consumed in the

The acetyl group (2C) of acetyl CoA combines with oxaloacetate (4C), this produces citrate (6C) which then goes through a sequence of electron yielding oxidation reactions, during which two CO2 molecules are released, restoring oxaloacetate. This is then used in the next cycle by re binding to another acetyl group. In the process the elections produced are transferred to electron carriers and are later used by the electron transport chains to drive proton pumps to generate ATP. The function of the citric acid cycle is the harvesting of high-energy electrons from carbon fuels.

For needed energy, a molecule of glucose is broken down through a process called glycolysis to form 2 ATP’s. The by-product is lactic acid. During intense, anaerobic muscle activity, anaerobic hydrolysis occurs. The Cori Cycle is activated to recycle the accumulated lactic acid back into useable energy. The lactic acid travels through the bloodstream to the oxygen-rich liver and is converted back to glucose by a process called gluconeogenesis. The glucose is then returned to the muscle to resupply it with energy. This conversion process uses up 6 ATP’s to make 2 ATP’s for the muscle to reuse. This creates a net loss of 4 ATP’s. The Cori cycle is meant to be a temporary shift of energy production from the oxygen-depleted muscles to the liver.

Glycolysis is followed by the Krebs cycle, however, this stage does require oxygen and takes place in the mitochondria. During the Krebs cycle, pyuvic acid is broken down into carbon dioxide in a series of energy-extracting reactions. This begins when pyruvic acid produced by glycolysis enters the mitochondria. As the cycle continues, citric acid is broken down into a 4-carbon molecule and more carbon dioxide is released. Then, high-energy electrons are passed to electron carriers and taken to the electron transport chain. All this produces 2 ATP, 6 NADH, 2 FADH, and 4 CO2 molecules.

2. (6 pts) Turn your head to the right. (Create a table* that describes which muscles move which bones across which joints under the control of which nerves)

Uniquely, glycolysis is both anaerobic and aerobic. The end product pyruvate, from glycolysis, is anabolized to lactic acid when there is a need for energy without an adequate supply of oxygen available. This last step or reaction enables glycolysis to continue producing ATP without the need for oxygen, which is why it is called the anaerobic energy system (Fink, 2009).

The two carbon molecule bonds four carbon molecule called oxaloacete forming a carbon molecule knew as citrate. The second step reaction is classified as oxidation/reductions reactions. This process is formed by two molecule of CO2 and one molecule of ATP. The cycle electrons reduce NAD and FAD, which join the H+ ions to form NADH and FADH2, this result to an extra NADH being formed during the transition. In the mitochondrion, four molecules of NADH and one molecule of FADH2 are produced for each molecule of pyruvate, two molecules of pyruyate enter the matrix for each molecule of oxidized glucose, as a result of these eight molecules of NADH+ two molecules are produced. Six molecules of NADH+, molecules of FADH2 and two molecules of ATP synthesize itself in Krebs cycle. As a result, no oxygen is used in the described reactions. During chimiosmosis, oxygen only plays a role in oxidative phosphorylation. The next step is the electron transport; the electrons are stored on NADH and FADH2 and are used to produce ATP. Electron transport chain is essential to make most ATP produced in cellular respiration. The NADH and FAD2 from the Krebs cycle drop their electrons at the beginning of the transport chain. When the electrons move along the electron transport chain, it gives power to pump the hydrogen along the membrane from the matrix into the intermediate space. This process forms a gradient concentration forcing the hydrogen through ATP syntheses attaching

Cellular respiration is a procedure that most living life forms experience to make and get chemical energy in the form of adenosine triphosphate (ATP). The energy is synthesized in three separate phases of cellular respiration: glycolysis, citrus extract cycle, and the electron transport chain. Glycolysis and the citric acid cycle are both anaerobic pathways because they do not bother with oxygen to form energy. The electron transport chain however, is aerobic due to its use of oxidative phosphorylation. Oxidative phosphorylation is the procedure in which ATP particles are created with the help of oxygen atoms (Campbell, 2009, p. 93). During which, organic food molecules are oxidized to synthesize ATP used to drive the metabolic reactions necessary to maintain the organism’s physical integrity and to support all its activities (Campbell, 2009, pp. 102-103).

As the diagram on the right displays, one molecule of Glucose produces two molecules of carbon dioxide and two molecules of ethanol. The fermentation of glucose to ethanol is only possible if oxygen is absent otherwise instead of producing ethanol and carbon dioxide, lactic acid is produced instead.

of glucose has 6 carbons), 2 ATP, 8 NADH and 2 FADH are produced. NADH and FADH