1. SDN Mobile is now free on iTunes and on the Google Play Store. Enjoy!
    Dismiss Notice
  2. New SDN Article! How To Choose Your Testing Center
    Dismiss Notice
  3. This forum is for support and discussion only. Please promote test prep materials/services (including AMAs) in the Special Offers subforum only. Thanks!
    Dismiss Notice
  4. Guest, be sure to check out How To Get Into Dental School, our free downloadable PDF with step-by-step details for dental school applicants!
    Dismiss Notice
SDN Mobile Article: Testing Center Test Prep Services Free Dental Admissions Guide

TopScore orgo question..

Discussion in 'DAT Discussions' started by prydA, May 7, 2008.

Previous Thread Next Thread
Loading...
  1. prydA

    prydA
    2+ Year Member

    Joined:
    Feb 7, 2008
    Messages:
    459
    Likes Received:
    0
    Status:
    Pre-Dental
    In topscore, test 2, o-chem question #86..

    Why is sucrose non-reducing? Doesn't the fructose ring in it have a free hemiacetal group? i know lactose is considered a reducing sugar.. what about it makes it a reducing one when compared to sucrose? i know the basic definition is that there is an aldehyde group it can open up to, but i dont understand it in this case.

    And why is fructose considered a ketohexafuranoside? did they mean the sucrose instead? i understand the furan part since it has 5 carbons, but what does the hexa- prefix have to do with anything?

    thanks for any help!
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
    #1 prydA, May 7, 2008
  2. Orgodox

    Orgodox
    7+ Year Member

    Joined:
    Feb 8, 2008
    Messages:
    636
    Likes Received:
    0
    Status:
    Dental Student
    In sucrose unlike most polysaccharides, the glycosidic bond is formed between the reducing ends of both glucose and fructose, and not between the reducing end of one and the nonreducing end of the other. The effect of this inhibits further bonding to other saccharide units. But the main thing is that even though fructose alone did have the hemiacetal group when it is in sucrose if does not

    To be a reducing sugar you would look for the hemiacetal group. This is not present in sucrose.

    [​IMG]
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
    #2 Orgodox, May 8, 2008
Previous Thread Next Thread
Loading...
(You must log in or sign up to post here.)

Share This Page