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    (repost) Just need a few clear points on how the structure of glucose relates to its function

    any help appreciated
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    Hi,

    Let us team up and tackle this Q together.

    I am sure we can work this out, don't you agree?

    OK here goes - let us look at the structure of glucose - empirical formula: C6H12O6.; structural formula - (take a look at it in your book or google images)

    Let us take it step by step: to work out how sructure is related to function, the first thing we need to delineate is the functions.

    1...Quick source of energy
    2. In some plants, used for storage
    3. As a building block [monomer] for more complex carbohydrates [polymers i.e. polysaccharides]
    4. To combine with other molecules to form structural chemicals like cellulose for e.g. plant cell wall, or like chitin for fugal cell wall.
    5. As a starting point to build amino acids hence proteins.

    Now we take 1-5 in turn and try to work out the relation to structure - makes sense?

    1. Small molecule that a) can be broken down into 2 3C molecules (pyruvate) for entry into Kreb's cycle to form ATP.
    ................................ .b) can enter the cell easily for the start of respiration = glycolysis
    ................................ .......c) water-soluble (has 4 -OH groups that can form hydrogen bonds) so fits in with the processes of life which all occur in aqueous solution.
    ................................ .......d) can cross blood-brain barrier to act as source of energy for brain (brain uses purely glucose as substrate).
    2. Glucose stored in onions, some fruits (e.g. bananas), in sugar cane - compact molecule that provides 4.1 Kcal per gram - efficient source of stored energy
    3. .Has free -OH and -H groups that can combine easily with others on another molecule of glucose (by condensation reaction dropping off H2O) to form disaccharide (maltose) then maltotriose, dextrins and amylose (1-4 linkages for straight chain and 1-6 linkages for branching).
    4. Has a ring structure that can form tough fibres as in cellulose for support function.
    5. Has three of the elements needed for proteins - C H and O - just need to add N (and e.g. S in methionine or cysteine) to convert to amino acids


    Ok - looking back at our work - we did not do that badly, did we? We got 8 separate ideas - an exam Q like this would probs be worth 5 marks, so we should score at least 4 even if one or two are not in the mark scheme yeah?

    I think you have a start now as to how to approach biology - defo not as an obese book to memorise - actually as an easy peasy, lemon squeezy subject that is great fun!


    M (specialist biology tutor)
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    (Original post by macpatelgh)
    Hi,

    Let us team up and tackle this Q together.

    I am sure we can work this out, don't you agree?

    OK here goes - let us look at the structure of glucose - empirical formula: C6H12O6.; structural formula - (take a look at it in your book or google images)

    Let us take it step by step: to work out how sructure is related to function, the first thing we need to delineate is the functions.

    1...Quick source of energy
    2. In some plants, used for storage
    3. As a building block [monomer] for more complex carbohydrates [polymers i.e. polysaccharides]
    4. To combine with other molecules to form structural chemicals like cellulose for e.g. plant cell wall, or like chitin for fugal cell wall.
    5. As a starting point to build amino acids hence proteins.

    Now we take 1-5 in turn and try to work out the relation to structure - makes sense?

    1. Small molecule that a) can be broken down into 2 3C molecules (pyruvate) for entry into Kreb's cycle to form ATP.
    ................................ .b) can enter the cell easily for the start of respiration = glycolysis
    ................................ .......c) water-soluble (has 4 -OH groups that can form hydrogen bonds) so fits in with the processes of life which all occur in aqueous solution.
    ................................ .......d) can cross blood-brain barrier to act as source of energy for brain (brain uses purely glucose as substrate).
    2. Glucose stored in onions, some fruits (e.g. bananas), in sugar cane - compact molecule that provides 4.1 Kcal per gram - efficient source of stored energy
    3. .Has free -OH and -H groups that can combine easily with others on another molecule of glucose (by condensation reaction dropping off H2O) to form disaccharide (maltose) then maltotriose, dextrins and amylose (1-4 linkages for straight chain and 1-6 linkages for branching).
    4. Has a ring structure that can form tough fibres as in cellulose for support function.
    5. Has three of the elements needed for proteins - C H and O - just need to add N (and e.g. S in methionine or cysteine) to convert to amino acids


    Ok - looking back at our work - we did not do that badly, did we? We got 8 separate ideas - an exam Q like this would probs be worth 5 marks, so we should score at least 4 even if one or two are not in the mark scheme yeah?

    I think you have a start now as to how to approach biology - defo not as an obese book to memorise - actually as an easy peasy, lemon squeezy subject that is great fun!


    M (specialist biology tutor)



    THANK YOU SO MUCH!!!! this is so helpful
 
 
 

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