# Aqa a level biology - protein question helpWatch

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Thread starter 4 weeks ago
#1
Hi guys, I was just wondering if anyone could help me out with this question:

1. Some enzymes digest protein. They hydrolyse the peptide bonds between amino acids. The extent to with 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.

ai) A protein molecule contains 151 amino acids. What is the total number of peptide bonds in this molecule? ANSWER = 150

ii) A molecule of this protein is digested. The DH value of the digested protein is 18. Calculate the number of peptide bonds that have been hydrolysed. (this is the question I'm stuck on) = ANSWER IS 27

I would be extremelyyyyyyy grateful for any help.
Thanks
0
4 weeks ago
#2
(Original post by hira.naz)
Hi guys, I was just wondering if anyone could help me out with this question:

1. Some enzymes digest protein. They hydrolyse the peptide bonds between amino acids. The extent to with 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.

ai) A protein molecule contains 151 amino acids. What is the total number of peptide bonds in this molecule? ANSWER = 150

ii) A molecule of this protein is digested. The DH value of the digested protein is 18. Calculate the number of peptide bonds that have been hydrolysed. (this is the question I'm stuck on) = ANSWER IS 27

I would be extremelyyyyyyy grateful for any help.
Thanks
Thats right
0
Thread starter 4 weeks ago
#3
I know haha but I don't know how to work it out I just looked at the mark scheme
(Original post by Kallum17)
Thats right
0
4 weeks ago
#4
(Original post by hira.naz)
I know haha but I don't know how to work it out I just looked at the mark scheme
Number of peptide bonds = number of amino acids take 1 because there isnt a peptide bonds at the end.
18/100= 0.18
0.18*150= 27
0
Thread starter 4 weeks ago
#5
oh my god... how did I over complicate it so much ahh. Thank you so much for your help
(Original post by Kallum17)
Number of peptide bonds = number of amino acids take 1 because there isnt a peptide bonds at the end.
18/100= 0.18
0.18*150= 27
0
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