The Krebs Cycle Essay

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.

Cellular Respiration is the physiological process of converting molecules into ATP. This process can occur in bacteria, protists, fungi, plants, and animals. It uses Oxygen (02) and Glucose (C6H1206) to transfer and transform electrons. Then it produces carbon dioxide (CO2) and Water (H2O). Thus, it is read as C6H12O6 + 6O2 --> 6H2O + 6CO2 + 32ATP. Respiration is split into three steps Glycolysis, Citric Acid Cycle, and Electron Transfer Chain (ETC).

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

The reaction for this process is: C6H12 O6 → 2C2H5 OH + 2CO2 + ATP This process also uses the glycolysis stage of respiration, however it can not use the Krebs cycle or electron transport as oxygen is required. Therefore without oxygen it allows cells to make small amounts of ATP.

One of the two pyruvate molecules that was generated from glycolysis enters the mitochondrial matrix where it is converted to acetyl CoA. Acetyl CoA initiates a cyclical series of reactions, creating the first compound in the Krebs cycle by transforming the last product formed in the Krebs cycle into Citrate. During the Krebs cycle, 1 ATP molecule is created and 3 molecules of carbon dioxide are released. Since only 1 of the 2 pyruvates is needed, the Krebs cycle repeats and six carbon dioxide molecules are released and the Krebs cycle forms two more ATP. Krebs cycle produces several molecules of NADH and FADH2, which will be used in creating more ATP in the third step of aerobic cellular respiration.

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 acetyl group from pyruvate is oxidised in a series of nine reactions; the citric acid cycle. Also known as the Krebs cycle, it is the second stage of cellular respiration. Cellular respiration is a 3 stage process where organic fuel molecules are broken down, in the presence of oxygen, to harvest energy. These reactions occur in the mitochondrial matrix.

The formula for cellular respiration is C6H12O6 + 6O2 ---> 6CO2 + 6H2O + Energy. This Equation is stating that Glucose + Oxygen changes into Carbon Dioxide + Water + ATP + Heat + Energy. The inputs of cellular respiration are the glucose (C6H12O6) and oxygen (6O2) part of the equation. The outputs of this process are Carbon Dioxide (6CO2), water (6H2O), ATP, and energy. There are three main steps to the cellular respiration process. First there is Glycolysis, which is the breakdown of glucose by enzymes, releasing energy and pyruvic acid. The next step is the Krebs cycle. The Krebs cycle is the sequence of reactions by which many living cells generate energy throughout an aerobic respirational process. It takes place in the mitochondria, taking

The third and final step in cellular respiration is the electron transport chain which takes place in the inner mitochondrion membrane. This process uses the high-energy electrons from the Krebs cycle to convert ADP into ATP. These high-energy electrons are first passed along the electron transport chain. Every time 2 electrons travel down this chain, their energy is used to transport hydrogen ions (H+) across the membrane. These H+ ions escape through channels into an ATP synthase. This causes it to spin, transforming the ADP into ATP. On average, each pair of high-energy electrons that moves down the electron

NADH will donate an electron to complex one and become NAD+. FAD2 will donate its electron to complex 2 and becomes FAD. Coenzyme Q accepts electrons from complex to 1 and 2 and donates to complex 3. Then complex 3 will transport its electron using the protein cytochrome C to complex 4. That electron will go to oxygen and form water as its product. Complex1, 3, and 4 in the process of transferring electrons will pump out Hydrogen ions to the other side of membrane. Lots of hydrogen ions are made and need to go somewhere where there is not a lot of them. ATP synthase will allow these hydrogen ions to go to the matrix in a controlled manner. The energy from these hydrogen ions will aid ADP and phosphate to make ATP. The formation of ATP in this process is called oxidative phosphorylation. The energy used in NADH and FAD2 is used to form the proton gradient (Sanders, 2013).

The key metabolic process depicted in step 1 is photosynthesis. In photosynthesis, step 1, carbon is moved through the cycle when carbon fixation happens. This is when carbon dioxide is fixed into organic molecules like glucose. To do this photosynthesis uses light energy in the form of ATP. The key metabolic process depicted in step 2 is cellular respiration. In cellular respiration, step 2, the reverse is performed in relation to photosynthesis. Organic molecules like glucose are hydrolyzed back into carbon dioxide. Energy from cellular respiration is released when the organic molecules are broken down, they then are used for other processes within the

Cellular respiration is composed of three steps, glycolysis, the Krebs cycle and the electron transport chain. Glycolysis is the first step of cellular respiration, which occurs in the cytoplasm and produces energy in the form of ATP. Glycolysis is the “process in which one glucose molecule is broken down to form two molecules of pyruvic acid” (cliffnotes, cellular

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).

In the metabolic reactions, oxidation-reduction reactions are very essential for ATP synthesis. The electrons removed in the oxidation are transferred to two major electron carrier enzymes. The electrons are transported through protein complexes in present in the inner mitochondrial membrane. The complexes contain attached chemical groups which are capable of accepting or donating one or more electrons. The protein complexes are known as the electron transfer system (ETS). The ETS allow distribution of the free energy between reduced coenzymes and the O2. The ETS is associated with proton (H+) pumping from the mitochondrial matrix to intermembrane space of the mitochondria.