Turn on thread page Beta
    • Thread Starter

    Hi guys, so the wording of this doesn't make sense: "The monomers of N-acetylglucosamine join by 1-4 glycosidic bonds to form the chitin molecule."
    Shouldn't it be the monomers of chitin which are N-acetylglucosamine molecules join by 1-4 glycosidic bonds to form the chitin molecule - because the monomers of N-acetylglucosamine are what makes up the N-acetylglucosamine molecule not the chitin molecule.
    Name:  10.PNG
Views: 15
Size:  47.9 KB

    Hi I think with the deterioration of the teaching of English in recent years, the examiner themselves are stating this Q in a confusing way - when they say the "monomers of N-acetylglucosamine.............." , what they are trying to say is "the monomers, namely N-acetylglucosamine...........".

    Yes, I don't blame you at all for being struck by this error in grammar on the part of the examiner:-

    If you look at the structure of N-acetylglucosamine (which is given), it is basically a glucose molecule with an acetyl group............:


    ...............in which one oxygen atom has been replaced by a nitrogen atom hence N-acetyl

    So, when several of these N-acetylglucosamine molecules join up by 1-4 glycosidic bonds (the -OH groups at the 1 and 4 positions unite dropping off H2O (= condensation reaction) forming -O- (the same bond that makes straight chain polysachharides from glucose monomers - [branching occurs by the formation of 1-6 bonds as in glycogen])), you get chitin, analogous to the formation of the polysaccharide amylose from glucose monomers (the main difference being the lack of N-acetyl groups in the latter, effectively the absence of nitrogen)

    I think I can safely say that your English is better than the examiner's - just try to take current exam Qs with a pinch of salt!

    M (specialist biology tutor)

    BTW - chitin is also the main constituent of the cell wall of fungal cells.
Submit reply
Turn on thread page Beta
Updated: March 5, 2018
The home of Results and Clearing


people online now


students helped last year

University open days

  1. Sheffield Hallam University
    City Campus Undergraduate
    Tue, 21 Aug '18
  2. Bournemouth University
    Clearing Open Day Undergraduate
    Wed, 22 Aug '18
  3. University of Buckingham
    Postgraduate Open Evening Postgraduate
    Thu, 23 Aug '18
A-level students - how do you feel about your results?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.