Please an anybody help me with this AS maths question about the degree of hydrolysis?

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Ggdf
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Hi

I would be greatly appreciative if anyone might be able to help me out.

I've just been going through an AS Biology practice exam paper and have come across a maths question that I really don't understand how to answer. This question is about degree of hydrolysis (explanation given below). The paper that has this question includes the answers, but unfortunately I really don't understand them/what I need to do to work out the question to arrive at these answers.

The question has three parts: a, b and c. I have posted it below.

I wonder if anyone might please be able to take a look at the question and explain to me what I must do to work out parts a, b and c.

I have included the correct answers given by the paper underneath. I would really like to understand the process of working out the question to arrive at these answers. If anyone could talk me through them that would be fantastic and hugely appreciated!

The question is:

Some enzymes digest protein. They hydrolyse the peptide bonds between amino acids. The extent to which a protein is digested is called the degree of hydrolysis (DH). The DH value may be calculated from the equation.

DH = 100 x number of peptide bonds hydrolysed/total number of peptide bonds present


a) A protein molecule contains 151 amino acids. What is the total number of peptide bonds in this molecule?

b) A molecule of this protein is digested. The DH value of the digested protein 18. Calculate the number of peptide bonds that have been hydrolysed.

c) What would be the DH value of a protein if it was completely hydrolysed to amino acids? Explain how you arrived at your answer.

The answers are:

a) 150
b) 27
c)100


I'm so confused and really worried something like this will come up in my real exam!
I'm bewildered with all of them, however question b is probably the one I'm most confused and concerned about.

Thank you very much!
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Eloades11
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(Original post by Ggdf)
Hi

I would be greatly appreciative if anyone might be able to help me out.

I've just been going through an AS Biology practice exam paper and have come across a maths question that I really don't understand how to answer. This question is about degree of hydrolysis (explanation given below). The paper that has this question includes the answers, but unfortunately I really don't understand them/what I need to do to work out the question to arrive at these answers.

The question has three parts: a, b and c. I have posted it below.

I wonder if anyone might please be able to take a look at the question and explain to me what I must do to work out parts a, b and c.

I have included the correct answers given by the paper underneath. I would really like to understand the process of working out the question to arrive at these answers. If anyone could talk me through them that would be fantastic and hugely appreciated!

The question is:

Some enzymes digest protein. They hydrolyse the peptide bonds between amino acids. The extent to which a protein is digested is called the degree of hydrolysis (DH). The DH value may be calculated from the equation.

DH = 100 x number of peptide bonds hydrolysed/total number of peptide bonds present


a) A protein molecule contains 151 amino acids. What is the total number of peptide bonds in this molecule?

b) A molecule of this protein is digested. The DH value of the digested protein 18. Calculate the number of peptide bonds that have been hydrolysed.

c) What would be the DH value of a protein if it was completely hydrolysed to amino acids? Explain how you arrived at your answer.

The answers are:

a) 150
b) 27
c)100


I'm so confused and really worried something like this will come up in my real exam!
I'm bewildered with all of them, however question b is probably the one I'm most confused and concerned about.

Thank you very much!
I think the first question is obvious, let me know if you really need me to go through it.

Second one is a simple equation, just plug the numbers into it.
18 = 100x/150 where 'x' is the number of peptide bonds hydrolysed

Thirdly, you now have the equation x = 100(150)/150 where 'x' is the DH value

Ask if you don't understand please
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SavannahG123
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Hi I'm sorry but could someone explain this to me please
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Dynamo123
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(Original post by SavannahG123)
Hi I'm sorry but could someone explain this to me please
The poster above you (By Eloades) just explained how to solve the question.

If you are still not sure, here's a tip: the number of peptide bonds in a protein is always one less than the total number of amino acids in that protein, because one peptide bond is formed between two amino acids.

Also, the rest is basic maths, which Eloades explained as well.

If you have a different question, do post it in a new thread
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SavannahG123
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(Original post by Dynamo123)
The poster above you (By Eloades) just explained how to solve the question.

If you are still not sure, here's a tip: the number of peptide bonds in a protein is always one less than the total number of amino acids in that protein, because one peptide bond is formed between two amino acids.

Also, the rest is basic maths, which Eloades explained as well.

If you have a different question, do post it in a new thread
Thank you very much for the tip!
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Saadpaad2003
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can you go through number 1
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