Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Jones on October 07, 2017, 10:09:59 PM
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I've checked several of the answers on here but couldn't see something that satisfied me. I've been asked to draw the structural formula for the reactants and products of Glycine + Valine. After that, I had to label the functional groups and linkages present, as well as show the peptide bond.
(https://upload.wikimedia.org/wikipedia/commons/thumb/6/6d/Peptidformationball.svg/300px-Peptidformationball.svg.png)
R1 = H and R2 = CH, w/ two branches leading to two CH3
Carboxyl = COOH Amino = NH2
Amino Acid (1) = Glycine Amino Acid (2) = Valine Dipeptide = Gly-Ala
My question is, is this right and have I fully answered the question?
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Are there any other functional groups present?
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If we were to look at the -OH then we can say that there is another functional group; hydroxyl.
That's all I can think of, do you see any other functional groups?
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Yes, but the -OH group is directly bonded to a carbonyl group (C=O), and when we put the two together we get a carboxylic acid. There is one other functional group present, and it's on the opposite side of the molecule.
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There's a carboxylic and an Amino group, but that's all I can think of/see. Am I missing something?
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Yes, the amino group is the other functional group that I was thinking of.
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Does that mean that I have everything answered and accurate?
I just realized that Glycine and Valine both have the double bond on the Oxygen on the top-so should I switch them? Does it matter where the double bond on the oxygen is?
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In your answer you have Gly-Ala, which is not the same as what you drew. In general there are several correct ways to draw a molecule.
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If you look at the bottom you'll see that I have the functional groups listed, as well as what stands for R1 (H) and R2 (CH leading to two CH3). Would that make what I drew accurate? What's missing, or can I hand it in?
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I think that the way that you labeled the side-chains is fine. I don't see any other problems.
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Sorry, but just to make sure: would this structure would be ok, disregarding the fact that the peptide bond, and functional groups aren't labelled?
(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fwps.prenhall.com%2Fwps%2Fmedia%2Fobjects%2F3313%2F3393159%2Fimag2509%2FAABAASO0.JPG&hash=f10937747a000a48db11da56678c94e7e94de7d4)
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Seems to me you're still missing the functional group in the middle. Unless I'm missing something about the question or the answer you provided.
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I thought that there were only two functional groups, and the peptide bond that joins them together? What functional group am I missing?
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I thought that there were only two functional groups, and the peptide bond that joins them together? What functional group am I missing?
The functional group that the peptide forms a part of.
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I'm not sure that that makes sense to me?
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I'm not sure that that makes sense to me?
The functional group that the peptide bond is a part of has an actual name. I'm talking about the RCONHR' part of the molecule (the carbonyl bonded to the nitrogen).
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So there's a carboxylic, carbonyl and ammonia group?
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The -CONH- part is a functional group as a whole (and has a specific name).
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So there's a carboxylic, carbonyl and ammonia group?
As Borek has said, the whole thing is a functional group with its own name. Perhaps look up the names and structures of carboxylic acid derivatives.
Also, as an aside, carbonyl groups are typically considered features of larger functional groups (ketones, aldehydes, etc). As well, ammonia is not a functional group, but a compound - NH3. This would be a type of amine, which is the name for the functional group.
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The other problem is one I mentioned previously, that you have written the wrong abbreviation for this particular dipeptide. Ala is the three letter abbreviation for the amino acid alanine. Is there an alanine residue in your product?
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As Borek has said, the whole thing is a functional group with its own name. Perhaps look up the names and structures of carboxylic acid derivatives.
Would it be Acetamide?
Also, as an aside, carbonyl groups are typically considered features of larger functional groups (ketones, aldehydes, etc). As well, ammonia is not a functional group, but a compound - NH3. This would be a type of amine, which is the name for the functional group.
So the functional groups are: amine, Carboxylic, Carbonyl (Aldehyde), and acetamide?
The other problem is one I mentioned previously, that you have written the wrong abbreviation for this particular dipeptide. Ala is the three letter abbreviation for the amino acid alanine. Is there an alanine residue in your product?
No, there isn't any residue of alanine-would it be accurate, then, to say that the abbreviation is Glycl-Valine?
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No. As I said in my last post, carbonyl is not really a functional group on its own. It's a feature of other functional groups. You also do not have an acetamide. You are very close, though. Where did you get aldehyde from? Are you actually looking at the structures of these functional groups and comparing with your structure?
You do also need to review three letter abbreviations for amino acids.
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No. As I said in my last post, carbonyl is not really a functional group on its own. It's a feature of other functional groups. You also do not have an acetamide. You are very close, though. Where did you get aldehyde from? Are you actually looking at the structures of these functional groups and comparing with your structure?
You do also need to review three letter abbreviations for amino acids.
Is it acetic acid, the other functional group for amide? I got the Aldehyde from the COOH, but that's carboxylic acid-isn't it? And yes, I am looking at both the chart for the functional group as well as my diagram and comparing them. I guess that there isn't a carbonyl group (aldehyde or ketone) because the C=O is a part of the peptide bond (or amide group)? So, there's a carboxylic acid, acetic acid and amine group? The abbreviation for valine is Val, and Gly for Glycine, therefore the name is Gly-Val?
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No. As I said in my last post, carbonyl is not really a functional group on its own. It's a feature of other functional groups. You also do not have an acetamide. You are very close, though. Where did you get aldehyde from? Are you actually looking at the structures of these functional groups and comparing with your structure?
You do also need to review three letter abbreviations for amino acids.
Is it acetic acid, the other functional group for amide? I got the Aldehyde from the COOH, but that's carboxylic acid-isn't it? And yes, I am looking at both the chart for the functional group as well as my diagram and comparing them. I guess that there isn't a carbonyl group (aldehyde or ketone) because the C=O is a part of the peptide bond (or amide group)? So, there's a carboxylic acid, acetic acid and amine group? The abbreviation for valine is Val, and Gly for Glycine, therefore the name is Gly-Val?
Once again, acetic acid is its own compound. COOH is a carboxylic acid.
I mentioned way back that the functional group is the one containing the peptide bond. I believe I have also said that it has a carbonyl. There are several functional groups that contain carbonyls - ketones, aldehydes, carboxylic acids, esters, to name a few. I suggest you reread the post I've quoted here of yours - you have mentioned the functional group in this post and not realised it. I further recommend you go over functional groups, what they are and how they look. You seem to be missing a lot of fundamental knowledge in this department.
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Amide is the functional group formed by the peptide bond (CONH).
(https://upload.wikimedia.org/wikipedia/commons/7/72/Amide.png)
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The other problem is one I mentioned previously, that you have written the wrong abbreviation for this particular dipeptide. Ala is the three letter abbreviation for the amino acid alanine. Is there an alanine residue in your product?
No, there isn't any residue of alanine-would it be accurate, then, to say that the abbreviation is Glycl-Valine?
The full name would be glycyl-valine, but the three-letter abbreviations are more frequently used.
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Amide is the functional group formed by the peptide bond (CONH).
(https://upload.wikimedia.org/wikipedia/commons/7/72/Amide.png)
Correct.
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So the functional groups are amine, carboxylic acid, and amide?