Login

Search the forums now!

Welcome, Guest. Please login or register.

May 08, 2024, 05:02:19 pm
Pages: [1]   Go Down

Author Topic: Re Peptide link  (Read 2430 times)  Share 

0 Members and 1 Guest are viewing this topic.

hifer

  • Victorian
  • Trendsetter
  • **
  • Posts: 110
  • Respect: 0
Re Peptide link
« on: November 02, 2007, 06:57:46 pm »
0
Hi guys, just wondering, when they ask you to circle the peptide link, do you circle the CONH or just CON? Coz this came up in the 2002 paper Section B Q3c, where the examiner's report only circled CON instead of CONH as they do in the textbook...

Can anyone clarify this with me?

Thanks
Logged

ninwa

  • Great Wonder of ATAR Notes
  • *******
  • Posts: 8267
  • Respect: +1021
Re Peptide link
« Reply #1 on: November 02, 2007, 07:02:42 pm »
0
pretty sure on VCAA exams its the CONH
Logged
ExamPro enquiries to [email protected]

bilgia

  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 410
  • Respect: +1
Re Peptide link
« Reply #2 on: November 02, 2007, 07:06:47 pm »
0
yep its CONH
Logged
My Subjects:
2006 I.T Systems --> 42
2007 English --> 40
         Methods --> 41
         Spec --> 38
         Chem --> 36
         Physics --> 37
         Unimaths --> 5.5

ENTER: 97.35


                   



 

hifer

  • Victorian
  • Trendsetter
  • **
  • Posts: 110
  • Respect: 0
Re Peptide link
« Reply #3 on: November 02, 2007, 07:15:01 pm »
0
hi there, I actually tried to clarify this with my teacher and he said that the actually peptide link is between the carbon-nitrogen bond, so when u draw the full structural formula, u shld only circle the C-N bond and not the O and H?

Does anyone else know this?
Logged

ninwa

  • Great Wonder of ATAR Notes
  • *******
  • Posts: 8267
  • Respect: +1021
Re Peptide link
« Reply #4 on: November 02, 2007, 07:29:46 pm »
0
Logged
ExamPro enquiries to [email protected]

Collin Li

  • VCE Tutor
  • Victorian
  • ATAR Notes Legend
  • *******
  • Posts: 4957
  • Respect: +17
Re Peptide link
« Reply #5 on: November 02, 2007, 07:30:18 pm »
0
Quote from: "hifer"
hi there, I actually tried to clarify this with my teacher and he said that the actually peptide link is between the carbon-nitrogen bond, so when u draw the full structural formula, u shld only circle the C-N bond and not the O and H?

Does anyone else know this?


H is not important.. the C=O part must be circled though (shows that it comes from -COOH group)
Logged

hifer

  • Victorian
  • Trendsetter
  • **
  • Posts: 110
  • Respect: 0
Re Peptide link
« Reply #6 on: November 02, 2007, 07:39:39 pm »
0
ic, thx!
Logged

Ahmad

  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1296
  • *dreamy sigh*
  • Respect: +15
Re Peptide link
« Reply #7 on: November 02, 2007, 08:29:37 pm »
0
I circle CONH. Would that be considered wrong?
Logged
Mandark: Please, oh please, set me up on a date with that golden-haired angel who graces our undeserving school with her infinite beauty!

The collage of ideas. The music of reason. The poetry of thought. The canvas of logic.

ninwa

  • Great Wonder of ATAR Notes
  • *******
  • Posts: 8267
  • Respect: +1021
Re Peptide link
« Reply #8 on: November 02, 2007, 08:35:11 pm »
0
Quote from: "ninwa"
http://www.vcaa.vic.edu.au/vce/studies/chemistry/assessreports/2004/chemassrepex204.pdf

see the answer for question 8a


*sigh* read that :P VCAA says circle CONH
Logged
ExamPro enquiries to [email protected]

Collin Li

  • VCE Tutor
  • Victorian
  • ATAR Notes Legend
  • *******
  • Posts: 4957
  • Respect: +17
Re Peptide link
« Reply #9 on: November 03, 2007, 10:36:17 am »
0
I said the H is not important. It means counting it or not is not critical.

Personally, I would though. Even though we are used to ignoring hydrogens on carbon chains, we usually never ignore the hydrogens attached to the nitrogen. The N-H is a "residue" of the -NH2 functional group (which partakes in the peptide bond formation), so it should be circled.

I think I should retract my earlier comment about H not being important though, I've convinced myself that CONH is the only answer.
Logged
Pages: [1]   Go Up