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    Variation in Alcohol dehydrogenase (ADH)

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    Over 10 varieties of the alcohol dehydrogenase molecule have been identified. All of them catalyze the same reaction. Hypothesize how these variations in the alcohol dehydrogenase molecule can explain why some individuals react differently to alcohol than others?
    Explain how more acetaldehyde is able to escape into the blood stream in certain individuals who lack the mitochondrial form of aldehyde dehydrogenase?
    Who would have the higher blood alcohol concentration if a man and women with the same weight consumed the same amount of alcohol? Why?
    Why is it that frequent and heavy drinkers become less intoxicated with larger amounts of alcohol?

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    Solution Preview

    I have explained in details the different alleles of the enzyme alcohol dehydrogenase (ADH), alcohol metabolization variance, blood alcohol content (BAC) in men and women and Physiology of heavy drinkers. Please go through all the references carefully.

    **ATTACHMENT: MS WORD DOCUMENT (with figures).


    When alcohol is consumed, it passes from the stomach and intestines into the blood, a process referred to as absorption. Liver is the organ where alcohol consumed is metabolized. Ethanol/alcohol is catalyzed by the enzyme alcohol dehydrogenase (ADH) to form acetaldehyde.
    Acetaldehyde is then converted to acetate by the enzyme aldehyde dehydrogenase (ALDH). Acetaldehyde is a toxic substance and body needs to get rid of it as soon as possible because even at low concentrations acetaldehyde produces unpleasant physiological reactions. Thus the presence and absence of mutation in the gene ALDH, which expresses the protein aldehyde dehydrogenase (ALDH) will affect dehydrogenase in turn affects drinking behaviors. Failure to quickly convert acetaldehyde to acetate can lead to severe consequences, which includes a rapid increase in blood flow to the skin of the face, neck, and chest, rapid heartbeat, headache, nausea, and extreme drowsiness occur.

    Figure 1: Metabolism of Alcohol in the liver(Reference: http://pubs.niaaa.nih.gov/publications/arh294/245-255.htm). ** Refer MS Word for figures.

    Acetaldehyde is eventually metabolized to carbon dioxide and water. The enzyme cytochrome P450IIE1 (CYP2E1), also plays a role in metabolizing alcohol. The concentration of this enzyme CYP2E1 increases in chronic drinkers (Lieber, C.S.1994.). Most of the alcohol consumed is metabolized in the liver, but the small quantity that remains unmetabolized permits alcohol concentration to be measured in breath and urine.

    Genetic Variations in ADH and ALDH can explain why different individuals react differently to alcohol. Variations in the genes encoding ADH and ...

    Solution Summary

    The material above explains the variations present in the Alcohol dehydrogenase (ADH) allele in different human population and how that results in variation in alcohol metabolizing abilities among individuals. Also explained above is the difference in Blood Alcohol Content (BAC) among men and women. The material also describes the reason heavy drinkers are able to consume more alcohol and still are less intoxicated.