Question 1092584: ``An octapeptide is known to contain four of one amino acid, two of another and two of third. How many different amino acid sequence are possible?( order matters in this question)
Answer by ikleyn(52933)   (Show Source):
You can put this solution on YOUR website! .
``An octapeptide is known to contain four of one amino acid, two of another and two of third.
How many different amino acid sequence are possible?( order matters in this question)
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I will assume that ALL sequences and connections are allowed in one-line-arrangement. And, as you stated in the condition,
the order amino acids in one-line arrangement does matter. Then the following logic works:
In total, there are 4 + 2 + 2 = 8 amino acid (acids ?).
Anyone of 8 acids can be placed in the 1-st position.
Anyone of remained 7 acids can be placed in the 2-nd position.
Anyone of remained 6 acids can be placed in the 3-rd position.
Anyone of remained 5 acids can be placed in the 4-th position.
. . . . and so on . . . .
Anyone of remained 2 acids can be placed in the 7-th position.
And there is no choice (except the remained 1 last acid) in the 8-th position.
If this logic is correct from the Chemistry/Biochemistry point of view,
then the answer is 8*7*6*5*4*3*2*1 = 40320 different amino acid sequences are possible.
Answer. How many different amino acid sequence are possible? - 40320 different amino acid sequences are possible.
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I am not a Chemist in my education, and consider this problem from the Combinatorics point of view ONLY.
So my logic easily can be wrong, if Biochemistry dictates other conditions.
It is your responsibility to evaluate if it is True or False.
If it not difficult to you, I would appreciate your feedback, which you can send me through the "Thank you" note.
In this case, please refer to the Problem ID number, which is 1092584.
Thank you and good luck !!
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From Wikipedia, https://en.wikipedia.org/wiki/Peptide
An octapeptide has eight amino acids (e.g., angiotensin II).
From Wikipedia, https://en.wikipedia.org/wiki/Angiotensin#Angiotensin_II
Angiotensin II
Asp-Arg-Val-Tyr-Ile-His-Pro-Phe | His-Leu
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My previous post/solution to this problem was
https://www.algebra.com/algebra/homework/Probability-and-statistics/Probability-and-statistics.faq.question.1091943.html
https://www.algebra.com/algebra/homework/Probability-and-statistics/Probability-and-statistics.faq.question.1091943.html
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And one last notice/question/request . . .
I got this message
Comment from student: If in this question order matters what is your answer ?
I think that this message came from you, although I am not 100% sure.
Every day I answer 10 - 20 - 30 posts, and in 3-4-5 days the number of my responses is about 1 hundred.
Under these circumstances, it is difficult to me to identify to which of my posts does relate the comment from a student,
if this comment does not refer to the problem ID. So, it is difficult to me to react adequately and timely . . .
Therefore, . . . please do refer to the problem's ID number if you want communicate with me effectively.
Again, thanks and good luck !
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