Abstract
The citric acid cycle, also known as the Krebs cycle and the tribocarboxylic acid cycle, is the hub of the metabolic wheel. The cycle earns this phrase due its role in the oxidation of various fuel molecules i.e. its catabolic nature, and in the provision of carbon skeletons for biosynthesis or its anabolic nature. Anaplerotic reactions are imperative as they replenish the anabolic reactions to ensure the cycle’s function is maintained. The citric acid cycle‘s central role in metabolism is also highlighted through its link to oxidative phosphorylation and the regulatory enzymes that adapt to different nutritional and health conditions.
Introduction
Aerobic respiration must occur in every living organism as it products are used to
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2). The cycle is broken into eight consecutive stages (Table 1). The first step initiating the cycle involves acetyl CoA reacting with oxaloacetate to first produce citryl CoA and then citrate from further hydrolysis. In the second step, citrate is isomerised into isocitrate. This is achieved through a dehydration and hydration step with cis-Aconistase produced as an intermediate and the aconitase catalysing the overall reaction. The third step involves isocitrate undergoing decarboxylation and oxidation reactions to form alpha-ketoglutarate (Berg J.M et al., 2015). In step four, a second decarboxylation oxidation reaction occurs to form succinyl CoA from alpha-ketoglutarate. Step five involves splitting succinyl CoA to produce succinate and CoA. In step six, succinate is oxidised to fumurate and FADH2 is formed simultaneously (Ness B., 2017). The penultimate step involves fumurate being converted to malate. In the affixing step of the citric acid cycle, malate is oxidised to form oxaloacetate, enabling a cycle to be established (Berg J.M et al., 2015).
The Citric acid cycle has catabolic and anabolic functions. Catabolic is defined as the breakdown of organic molecules and anabolic means essentially the opposite - the synthesis of organic molecules. The citric acid cycle is used as an energy source for oxidative phosphorylation and has a role in the metabolic pathways of lipids, carbohydrates and proteins. These functions and links will be explored further in this
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The catabolic role the cycle plays involves the degradation of products and reactants involved in the cycle to produce ATP. This function appears to be the salient function of the cycle. The citric acid cycle is the final pathway for the oxidation of carbohydrates, lipids and proteins due to the use in amino acids metabolism (Cox M.M et al.,2017). Acetyl CoA has an amphibolic role. It fulfils its catabolic role by entering the citric acid cycle for the breakdown of amino acids. The catabolism of amino acids provides succinate, oxaloacetate, fumarate and alpha-ketoglutarate. These products are then utilized for the anabolic nature of the cycle. Hence why, the citric acid cycle is the hub of the metabolic wheel as the molecules produced through amphibolic reactions are vital for metabolism in the body. Catabolic reactions are also important for harvesting high energy electrons (Berg J.M et al.,
2. The conversion of pyruvate to acetaldehyde is done by the release of CO₂ and enzyme pyruvate decarboxylase.
Animal metabolism consists of the utilization of nutrients absorbed from the digestive tract and their catabolism as fuel for energy or their conversion into substances of the body. Metabolism is a continuous process because the molecules and even most cells of the body have brief lifetimes and are constantly replaced, while tissue as a whole maintains its characteristic structure. This constant rebuilding process without a net change in the amount of a cell constituent is known as dynamic equilibrium (Grolier1996). In the combustion of food, oxygen is used and carbon dioxide is given off. The rate of oxygen consumption indicates the energy expenditure of an organism, or its metabolic rate (Grolier1996).
... which is catalyzed by b-ketoacyl CoA thiolase. The products are acetyl-CoA and a long chain fatty acyl CoA that is 2 carbons shorter than the original fatty acyl CoA. One complete round of β-oxidation cleaves 2 carbons from the fatty acid chain, and the process continues until the entire fatty acid chain is broken down into acetyl propinoyl CoA. For example, an 18 carbon chain fatty acid would need to go through 9 rounds of β-oxidation in order to be completely metabolized.
The CoQ10 stays in the mitochondria. This is the energy-generating component of the body cells. This coenzyme produces the ATP or adenosine-5-triphosphate. The ATP boosts protein synthesis and muscle contraction processes.
Its ability to inhibit phosphodiestarase type 1 leading to an increase in the concentration of cyclic AMP which is thought to result in its vasodilator effects
Exercise and the act of any bodily motion requires chemistry to power all of the necessary moving parts. There are two functions of exercise that make you feel good while working out and then make you feel not so good. The first “feel good” process is the releasing of endorphins during a workout. Endorphins are chemicals released by the pituitary gland of the brain. The pituitary gland produces approximately 20 different types of endorphins that assist the human body with a variety of functions. Endorphins diminish the brain’s ability to perceive pain, which is similar to the function of sedatives. A few examples of the benefits of endorphins are that they help with stress reduction, relieving pain, boosting immunity, slowing the aging process,
Three steps can explain cellular respiration: glycolysis, the TCA cycle (or citric acid cycle or Krebs cycle), and oxidative phosphorylation. Glycolysis is divided into two different stages: energy investment and energy payoff. During glycolysis, “ATP is both required and released at different stages” (Jordan & North 2013). The result is a net gain of two ATP, two NADH, and the production of two pyruvates. This process takes place in the cytoplasm. The pyruvates then go through the plasma membrane and into the mitochondrial matrix. During this pyruvate processing, NADH and CO2 are released and the pyruvates are converted into acetyl CoA. The acetyl CoA then goes through the TCA cycle, producing ATP, NADH, FADH2, and CO2. Finally, NADH and FADH2 go through the electron transport cha...
When the aerobic organisms in the body consume all the oxygen present, anaerobic organisms from the digestive system begin to multiply. They consume macromolecules (proteins, carbohydrates, lipids) and form acids and gases in the p...
Membranes play an integral function in trapping and securing metabolic products within the borders of a cell within an aqueous environment. Without a selectively permeable border surrounding sites of anabolic function, potential useful products of this metabolism would simply diffuse away in the aqueous environment contained within and surrounding the cell. However, securing metabolites within the cell also comes with a price of not being able to acquire potentially useful compounds from the surrounding environment. Some very small gases and polar uncharged compounds are able to simply diffuse across this membrane, moving to the site of lower concentration on either side of the membrane. However, larger uncharged and charged polar molecules,
The indirect applications are based on the idea that without ATP synthase, cellular respiration would achieve very little. This includes religious fasting and bioremediation. During religious fasting, there is generally little to no fresh input of nutrient. So the body must use fat reserves in the body to perform cellular respiration. The lipids stored in the body take a related metabolic pathway. Eventually the energy extracted from the fat fuels ATP synthase that makes ATP to be used by the body for energy, even though there is no input of nutrients. Bioremediation is the use of genetically modified organism to eat away at pollutants in the soil water. ATP synthase is related to this process as the waste becomes the input of nutrient that takes a related metabolic pathway for cellular respiration that occurs in the cells of the organism. Eventually the waste’s energy is used to create a concentration gradient and ATP synthase creates ATP to continue fueling the degradation of the pollutants. The direct applications of ATP synthase is the contributions to the light independent reactions. ATP synthase creates ATP to be used in the Calvin cycle. The importance of the Calvin cycle is that it takes the energy from the light dependent reaction and creates a sugar to be sent to cellular respiration. This process requires energy, which is provided by ATP synthase. This enzyme is
The enzymes have active sites on their surfaces to allow the binding of a substrate through the help of coenzymes to form enzyme-substrate complex. The chemical reaction thus converts the substrate to a new product then released and the catalytic cycle proceeds.
Cellular respiration and photosynthesis are important in the cycle of energy to withstand life as we define it. Cellular respiration and photosynthesis have several stages in where the making of energy occurs, and have diverse relationships with organelles within the eukaryotic cell. These processes are central in how life has evolved.
Fermentation is an anaerobic process in which fuel molecules are broken down to create pyruvate and ATP molecules (Alberts, 1998). Both pyruvate and ATP are major energy sources used by the cell to do a variety of things. For example, ATP is used in cell division to divide the chromosomes (Alberts, 1998).
ix. citric acid increases the acidity of foods and makes it harder for bacteria to
Step 1 is repeated by using different yeast strains, a pet 1 and M240 into all 6 conical