Ethanol can be a significant source of energy for people who consume large quant

Question

Ethanol can be a significant source of energy for people who consume large quantities of alcoholic NOTE: Reference material journal articles and review papers) on the subject of Alcohol Metabolism is provided in the Bb Learning Resources section to help you answer Question 3. a) Complete the table below showing the energy density of the major food groups (carbohydrates, fats .Show energy density of the nutrients as kJig and kcal/g (caloric value) in rank order (highest .Give accurate data. For the energy density values you give, check that the values conform to and proteins) and ethanol, in a rank order of highest to lowest energy density to lowest. the standard conversion factor of 1 kcal = 4.184 kJ OR 1 kJ = 0.239 kcal. Often data sourced from textbooks and websites have been rounded up or down (or sideways) and this affects the kJ kcal relationship. CHECK YOUR NUMBERS! Energy density Nutrient (in rank order) kJig kcal/g (2 marks) b) In humans, the pathway of ethanol metabolism converts ethanol to acetate, which can then be used to generate acetyl CoA and either enter into the tricarboxylic acid cycle or be utilised for fatty acid synthesis. Draw the pathway that converts ethanol to acetate and, then, to acetyl CoA. o o o o Show each step in the pathway, include all the names of the intermediates. Include the names of the enzymes responsible for each step. Include details of coenzymes/cosubstrates that may be used in these reactions. Note the subcellular localisation of the steps in the pathway. (4 marks) c) Name two (2) additional enzymes or enzyme systems that are involved in the conversion of ethanol to acetaldehyde in humans. (1 mark)

Explanation / Answer

a)Energy density : a) fats: 37.68 kj/g, 9 kcal/g,b) ethanol( alcohol) 29.31kj/g, 7 kcal/g,c) carbohydrates:16.75kj/g and 4 kcal, d) proteins 16.75kj/g and 4kcal. b)Ethanol metabolism : when alcohol in the form os ethanol is consumed the majority enters the systemic circulation, where it can then be metabolized in the liverviz the enzyme alcohol dehydrogenase this enzyme oxidizes ethanol to actealdehyde while reducing NAD to NADH which is then oxidized to acetate by the enzyme aldehyde dehydrogenase reducing another equivalent to NAD to NADH the acetate produced via aldehydedehydrogenase in the liver is then transported to peripheral tissues where it is converted to acetyl -CoA ,( They are 2 pathways the primary pathway for alcoho, dehydrogenase a cytosolic enzyme that caytalyses the conversion of alcohol to acetaldehye, during conversion of ethanol to aldehyde hydrogen ion is transfered from alcohol to the cofactor NAD to form NADH , the other pathway is the microsomal ethanol oxidising system it uses NADPH as a cofacctorin the metabolism of ethanol) c) The enzymes used in the conversion of alcohol to aldehydes is mitochondrial NAD dependent aldehyde dehydrogenase. and alcohol dehydrogenase. d) 1) In ethylene glycol poisoning: the toxicity is due the metabolities of ethylene glycol primarily it is metabolized by alcohol dehydrogeanse to glycoaldehyde which is then oxidised to glycolic acid by aldehyde dehydrogenasem then the increase in the metabolities may cause cerebral edema and renal failure and heart diseases etc. ethylene glycol to glycoaldehyde by the action of alcohol dehydrogeanse and then glycoaldehyde to glycolic acid by the action of aldehyde dehydrogenase and then glycolic acid to glyoxylic acid it then break down into to alpha hydroxy beta ketoadipic acid and oalic acid and glycine. 2)the treatment for ethylene glycol poisining is stabilizing the patient as ethylene glycol and the antidotal treatment for the management of ethylene glycol poisoning are ethanol and fomepizole, and then henodialysis. 3) Reversible enzyme inhibition in the ethylene glycol is ethanol   

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