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March 19, 2024, 01:12:26 pm

Author Topic: SUGGESTED ANSWERS!!!  (Read 40894 times)

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Bhootnike

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Re: SUGGESTED ANSWERS!!!
« Reply #60 on: June 13, 2012, 06:38:30 pm »
Would the answer for Question 1 a i be galactose because of the rearrangement of carbon fours hydroxyl group from positioned down to a up position?   :-\ :-\ :o

i think its just general fact that cellulose is a polymer of glucose.
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Re: SUGGESTED ANSWERS!!!
« Reply #61 on: June 13, 2012, 06:39:07 pm »
could you write mass spec for 4d?

sin0001

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Re: SUGGESTED ANSWERS!!!
« Reply #62 on: June 13, 2012, 06:39:31 pm »
would the answer be B for question 6 on Multiple choice?
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vagrantshades

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Re: SUGGESTED ANSWERS!!!
« Reply #63 on: June 13, 2012, 06:40:14 pm »
wb 12, i thought retention time stays the same :'(



must have read it wrong
my bad

Q 5...
i really think it's A
though it's a bit ambigous as they can be in z side chains, maybe 2 correct sols?

I think the option should have said C=O and N-H functional groups in the peptide linkage or something. A should definitely be correct, not sure if they should accept D though.

It said ' in the secondary structure...'
so that would automatically imply hydrogen bonding b/w amide groups! which i believe option II satisfies?

Actually, the full statement is "The secondary structure of a protein is the result of hydrogen bonding between -NH and -CO groups".
Bonding between -NH and -CO groups in sidechains doesn't result in the maintenance of the secondary structure, that's tertiary structure. :/

charmanderp

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Re: SUGGESTED ANSWERS!!!
« Reply #64 on: June 13, 2012, 06:40:28 pm »
Isn't MC
i had

5) A
12) C?

12 was C. 5 was D because it's not technically false to say that the secondary structure involves hydrogen bonds between N-H and C-O groups. Because that is the case. If it had said that it involved hydrogen bonds between all N-H and C-O that would be untrue.

It would be false, because the secondary structure isn't maintained by hydrogen bonds between N-H and C-O groups in the side chains. By saying between N-H and C-O groups, it still includes those side chains. So I guess they might have to accept two answers then.

It doesn't include side chains at all. It mentioned only the nature of the bonding and from which atoms it stemmed, not from whereabouts on the molecule those atoms were. Regardless, hydrogen bonding in the tertiary structure doesn't occur between N-H and C=O groups.

I was so tempted to write beta glucose for that question but I couldn't remember what the symbol for beta looked like haha.
« Last Edit: June 13, 2012, 06:44:20 pm by charmanderp »
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sin0001

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Re: SUGGESTED ANSWERS!!!
« Reply #65 on: June 13, 2012, 06:40:38 pm »
and for the average mass of Iron question, could you have found the average of the four concentrations (100-400) and used that to find the mass?
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jessiele

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Re: SUGGESTED ANSWERS!!!
« Reply #66 on: June 13, 2012, 06:41:19 pm »
hey thushan, you know for ques 13 of multiple choice, shouldn't it be 2.50M, because c(H) = 10 M from the original,
the volume is changed from 15mL to 60mL, so it's diluted by a factor of 4, what I did was dividing 10 by 4 , and i got 2.50 M
or did I get it wrong?

Tonychet2

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Re: SUGGESTED ANSWERS!!!
« Reply #67 on: June 13, 2012, 06:42:40 pm »
Question 6aii)30mg

At 0mg/l the absorbance value was 0.06 therefore you need to subtract this from the average absorbance value.

interesting point. and to the other person use c1v1 = c2v2 to solve for c2,

vagrantshades

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Re: SUGGESTED ANSWERS!!!
« Reply #68 on: June 13, 2012, 06:42:56 pm »
Isn't MC
i had

5) A
12) C?

12 was C. 5 was D because it's not technically false to say that the secondary structure involves hydrogen bonds between N-H and C-O groups. Because that is the case. If it had said that it involved hydrogen bonds between all N-H and C-O that would be untrue.

It would be false, because the secondary structure isn't maintained by hydrogen bonds between N-H and C-O groups in the side chains. By saying between N-H and C-O groups, it still includes those side chains. So I guess they might have to accept two answers then.

It doesn't include side chains at all. It mentioned only the nature of the bonding and from which atoms it stemmed, not from whereabouts on the molecule those atoms were.

I was so tempted to write beta glucose for that question but I couldn't remember what the symbol for beta looked like haha.

Yeah but because it doesn't mention WHERE those atoms are, it doesn't rule out the atoms in the side chains. Secondary structure is specifically maintained by those atoms in the peptide linkage, it can't be from anywhere else in the polypeptide.

jasoN-

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Re: SUGGESTED ANSWERS!!!
« Reply #69 on: June 13, 2012, 06:44:00 pm »
hey thushan, you know for ques 13 of multiple choice, shouldn't it be 2.50M, because c(H) = 10 M from the original,
the volume is changed from 15mL to 60mL, so it's diluted by a factor of 4, what I did was dividing 10 by 4 , and i got 2.50 M
or did I get it wrong?
The volume is changed from 15mL to 75mL (added 60)
c1v1 = c2v2
c2 = (10*15)/75 = 2M, C
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jasoN-

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Re: SUGGESTED ANSWERS!!!
« Reply #70 on: June 13, 2012, 06:44:56 pm »
Isn't MC
i had

5) A
12) C?

12 was C. 5 was D because it's not technically false to say that the secondary structure involves hydrogen bonds between N-H and C-O groups. Because that is the case. If it had said that it involved hydrogen bonds between all N-H and C-O that would be untrue.

It would be false, because the secondary structure isn't maintained by hydrogen bonds between N-H and C-O groups in the side chains. By saying between N-H and C-O groups, it still includes those side chains. So I guess they might have to accept two answers then.

It doesn't include side chains at all. It mentioned only the nature of the bonding and from which atoms it stemmed, not from whereabouts on the molecule those atoms were.

I was so tempted to write beta glucose for that question but I couldn't remember what the symbol for beta looked like haha.

Yeah but because it doesn't mention WHERE those atoms are, it doesn't rule out the atoms in the side chains. Secondary structure is specifically maintained by those atoms in the peptide linkage, it can't be from anywhere else in the polypeptide.

That's a very fair point, hopefully they will award marks for both A and D

Edit: But you would be pretty lucky if they give you a mark for A. The statement is 100% true in that the result of the secondary structure IS FROM H-bonding between -NH and -CO groups. It doesn't necessarily have to say 'in the peptide bonds of the amino acids' or something to that effect.
« Last Edit: June 13, 2012, 06:51:37 pm by jasoN- »
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Bhootnike

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Re: SUGGESTED ANSWERS!!!
« Reply #71 on: June 13, 2012, 06:46:06 pm »
wb 12, i thought retention time stays the same :'(



must have read it wrong
my bad

Q 5...
i really think it's A
though it's a bit ambigous as they can be in z side chains, maybe 2 correct sols?

I think the option should have said C=O and N-H functional groups in the peptide linkage or something. A should definitely be correct, not sure if they should accept D though.

It said ' in the secondary structure...'
so that would automatically imply hydrogen bonding b/w amide groups! which i believe option II satisfies?

Actually, the full statement is "The secondary structure of a protein is the result of hydrogen bonding between -NH and -CO groups".
Bonding between -NH and -CO groups in sidechains doesn't result in the maintenance of the secondary structure, that's tertiary structure. :/

when you say 'sidechain' are you referring to Z'group? or the Amino and carboxyl groups on AA's?
sec. structure for me is defined as the coiling of the polypeptide strand due to H-bonding between amide groups.
-NH and -CO groups, as it says in the question are bonded via hydrogen bonding in the sec. structure, thus making amide/peptide linkage.
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charmanderp

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Re: SUGGESTED ANSWERS!!!
« Reply #72 on: June 13, 2012, 06:48:36 pm »
Isn't MC
i had

5) A
12) C?

12 was C. 5 was D because it's not technically false to say that the secondary structure involves hydrogen bonds between N-H and C-O groups. Because that is the case. If it had said that it involved hydrogen bonds between all N-H and C-O that would be untrue.

It would be false, because the secondary structure isn't maintained by hydrogen bonds between N-H and C-O groups in the side chains. By saying between N-H and C-O groups, it still includes those side chains. So I guess they might have to accept two answers then.

It doesn't include side chains at all. It mentioned only the nature of the bonding and from which atoms it stemmed, not from whereabouts on the molecule those atoms were.

I was so tempted to write beta glucose for that question but I couldn't remember what the symbol for beta looked like haha.

Yeah but because it doesn't mention WHERE those atoms are, it doesn't rule out the atoms in the side chains. Secondary structure is specifically maintained by those atoms in the peptide linkage, it can't be from anywhere else in the polypeptide.
What you're essentially doing then is saying that statement II was not true. But it is true.

Hydrogen bonding in the tertiary structure occurs between other groups too (hydroxyls, etc) and I'm not entirely sure that amines and carboxys do form hydrogen bonds in the tertiary structure.
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vagrantshades

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Re: SUGGESTED ANSWERS!!!
« Reply #73 on: June 13, 2012, 06:49:42 pm »
Question 6aii)30mg

At 0mg/l the absorbance value was 0.06 therefore you need to subtract this from the average absorbance value.

Mmmm yes but it depends what graph you're using.

If you subtracted 0.06 from all your variables, and you draw your graph through the origin, you'll end up with the same results I think? Because if your graph doesnt' run through the origin, you don't minus the 0.06, at least I'm pretty sure you don't have to.

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Re: SUGGESTED ANSWERS!!!
« Reply #74 on: June 13, 2012, 06:50:00 pm »
4) c) you need to obtain PURE propyl probanoate so you need to do fractional distillation to get the pure form.
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