How many possible combinations of amino acids are there?
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AlphaArgonian
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#1
Ok so I'll give any people who haven't studied A-level (or equivalent) biology some context:
Amino acids are biological molecules that make up proteins, there are 20 (known) of them. some examples are glycine, valine and tryptophan.
Proteins form from unique combinations of these amino acids...
Now, textbooks say there are 8000 (20^3) combinations...
My teacher and I argue that there are 20! combinations...
Help?
Amino acids are biological molecules that make up proteins, there are 20 (known) of them. some examples are glycine, valine and tryptophan.
Proteins form from unique combinations of these amino acids...
Now, textbooks say there are 8000 (20^3) combinations...
My teacher and I argue that there are 20! combinations...
Help?
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username1793709
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#2
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#2
Because amino acids can be arranged in many different combinations, it's possible for your body to make thousands of different kinds of proteins from just the same 21 amino acids. You may see books that say there are only 20 amino acids.
Hope this explains it
There's 20 amino acids, but thousands of proteins (I think)
Hope this explains it

There's 20 amino acids, but thousands of proteins (I think)
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Serine Soul
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#3
Pretty sure it's 20! different combinations 
But I guess there's a fewer amount in nature....
Interesting questions

But I guess there's a fewer amount in nature....
Interesting questions
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Arbolus
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The answer is infinite, for all intents and purposes, because there's no theoretical limit on how long a peptide chain can be. In general, if you have a chain of n objects, each of which can be one of 20 different options, and there is no limit on how many times each option can be used, the number of possible combinations is 20n.
20! is the number of ways of arranging 20 different amino acids in a chain if each acid can only be used once.
20! is the number of ways of arranging 20 different amino acids in a chain if each acid can only be used once.
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Serine Soul
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#5
(Original post by Arbolus)
The answer is infinite, for all intents and purposes, because there's no theoretical limit on how long a peptide chain can be. In general, if you have a chain of n objects, each of which can be one of 20 different options, and there is no limit on how many times each option can be used, the number of possible combinations is 20n.
20! is the number of ways of arranging 20 different amino acids in a chain if each acid can only be used once.
The answer is infinite, for all intents and purposes, because there's no theoretical limit on how long a peptide chain can be. In general, if you have a chain of n objects, each of which can be one of 20 different options, and there is no limit on how many times each option can be used, the number of possible combinations is 20n.
20! is the number of ways of arranging 20 different amino acids in a chain if each acid can only be used once.
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AlphaArgonian
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AlphaArgonian
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#7
(Original post by Porcupayne)
Because amino acids can be arranged in many different combinations, it's possible for your body to make thousands of different kinds of proteins from just the same 21 amino acids. You may see books that say there are only 20 amino acids.
Hope this explains it
There's 20 amino acids, but thousands of proteins (I think)
Because amino acids can be arranged in many different combinations, it's possible for your body to make thousands of different kinds of proteins from just the same 21 amino acids. You may see books that say there are only 20 amino acids.
Hope this explains it

There's 20 amino acids, but thousands of proteins (I think)
Damnit, this better not be one of those "a student at this education stage would not understand it" situations...
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username1793709
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#8
(Original post by AlphaArgonian)
There's 21?
Damnit, this better not be one of those "a student at this education stage would not understand it" situations...
There's 21?
Damnit, this better not be one of those "a student at this education stage would not understand it" situations...
It's a topic for debate whether it should be included aha
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AlphaArgonian
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#9
(Original post by Porcupayne)
Haha!! There's 20 common amino acids, but selenocysteine (the 21st) is found in a very small number of proteins in humans as well!!
It's a topic for debate whether it should be included aha
Haha!! There's 20 common amino acids, but selenocysteine (the 21st) is found in a very small number of proteins in humans as well!!
It's a topic for debate whether it should be included aha
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nexttime
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#10
(Original post by AlphaArgonian)
... some kind of unique molecular complex...
... some kind of unique molecular complex...

I'd like context for that textbook as it just seems bizarre that you'd only have your protein 3 acids long. Were they talking about an example chain of 3 amino acids in the context of a longer protein? In which case the specific order is important and it would indeed be 20^3 (for that tiny subsection).
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futureDOCTOR2k15
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#11
There can be more than 20! combinations of different amino acids.
And there are over 200 amino acids tbh....just that 20-22 (some sources say 20..21 or 22) are used for protein synthesis....rest are used for different purposes such as neurotransmitters as acetylcholine(Studying this in A2 bio right now
)
* for a levels tho I always use 20 amino acids as it is the "safe" no. to use
And there are over 200 amino acids tbh....just that 20-22 (some sources say 20..21 or 22) are used for protein synthesis....rest are used for different purposes such as neurotransmitters as acetylcholine(Studying this in A2 bio right now

* for a levels tho I always use 20 amino acids as it is the "safe" no. to use
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Aubrey_79
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(Original post by AlphaArgonian)
Ok so I'll give any people who haven't studied A-level (or equivalent) biology some context:
Amino acids are biological molecules that make up proteins, there are 20 (known) of them. some examples are glycine, valine and tryptophan.
Proteins form from unique combinations of these amino acids...
Now, textbooks say there are 8000 (20^3) combinations...
My teacher and I argue that there are 20! combinations...
Help?
Ok so I'll give any people who haven't studied A-level (or equivalent) biology some context:
Amino acids are biological molecules that make up proteins, there are 20 (known) of them. some examples are glycine, valine and tryptophan.
Proteins form from unique combinations of these amino acids...
Now, textbooks say there are 8000 (20^3) combinations...
My teacher and I argue that there are 20! combinations...
Help?
20 amino acids
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AlphaArgonian
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#13
That basically implies each amino acid only has one triplet code assigned to it. But we know plenty of amino acids have a degenerate code.
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Aubrey_79
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#14
(Original post by AlphaArgonian)
Dude that sounds waaaaaayyyyyyyyyy too small.
That basically implies each amino acid only has one triplet code assigned to it. But we know plenty of amino acids have a degenerate code.
Dude that sounds waaaaaayyyyyyyyyy too small.
That basically implies each amino acid only has one triplet code assigned to it. But we know plenty of amino acids have a degenerate code.
4=base
3=triplet
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username1560589
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(Original post by AlphaArgonian)
Ok so I'll give any people who haven't studied A-level (or equivalent) biology some context:
Amino acids are biological molecules that make up proteins, there are 20 (known) of them. some examples are glycine, valine and tryptophan.
Proteins form from unique combinations of these amino acids...
Now, textbooks say there are 8000 (20^3) combinations...
My teacher and I argue that there are 20! combinations...
Help?
Ok so I'll give any people who haven't studied A-level (or equivalent) biology some context:
Amino acids are biological molecules that make up proteins, there are 20 (known) of them. some examples are glycine, valine and tryptophan.
Proteins form from unique combinations of these amino acids...
Now, textbooks say there are 8000 (20^3) combinations...
My teacher and I argue that there are 20! combinations...
Help?
Therefore the number of combinations is

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username1560589
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#16
(Original post by futureDOCTOR2k15)
There can be more than 20! combinations of different amino acids.
And there are over 200 amino acids tbh....just that 20-22 (some sources say 20..21 or 22) are used for protein synthesis....rest are used for different purposes such as neurotransmitters as acetylcholine(Studying this in A2 bio right now
)
* for a levels tho I always use 20 amino acids as it is the "safe" no. to use
There can be more than 20! combinations of different amino acids.
And there are over 200 amino acids tbh....just that 20-22 (some sources say 20..21 or 22) are used for protein synthesis....rest are used for different purposes such as neurotransmitters as acetylcholine(Studying this in A2 bio right now

* for a levels tho I always use 20 amino acids as it is the "safe" no. to use

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Ambitious1999
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#17
There are around 21 common amino acids.
Each amino acid is chosen from the genes by a code consisting of 3 base pairs. The arrangement of this code determines what Amino acids make up the polypeptide chain.
An infinite number of combinations is possible especially considering gene mutations. Cancer cells for example produce proteins and peptides that are unknown of.
Each amino acid is chosen from the genes by a code consisting of 3 base pairs. The arrangement of this code determines what Amino acids make up the polypeptide chain.
An infinite number of combinations is possible especially considering gene mutations. Cancer cells for example produce proteins and peptides that are unknown of.
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rajboy3
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#18
(Original post by Arbolus)
The answer is infinite, for all intents and purposes, because there's no theoretical limit on how long a peptide chain can be. In general, if you have a chain of n objects, each of which can be one of 20 different options, and there is no limit on how many times each option can be used, the number of possible combinations is 20n.
20! is the number of ways of arranging 20 different amino acids in a chain if each acid can only be used once.
The answer is infinite, for all intents and purposes, because there's no theoretical limit on how long a peptide chain can be. In general, if you have a chain of n objects, each of which can be one of 20 different options, and there is no limit on how many times each option can be used, the number of possible combinations is 20n.
20! is the number of ways of arranging 20 different amino acids in a chain if each acid can only be used once.

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QuentinM
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#19
Definitely infinite, depends on the following factors:
*Whether amino acids repeat in a sequence (they do frequently)
*How long the sequence is....a small peptide (e.g. insulin)? or a larger protein (e.g. actin/ATPase)
*Whether amino acids repeat in a sequence (they do frequently)
*How long the sequence is....a small peptide (e.g. insulin)? or a larger protein (e.g. actin/ATPase)
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bobby147
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#20
(Original post by QuentinM)
Definitely infinite, depends on the following factors:
*Whether amino acids repeat in a sequence (they do frequently)
*How long the sequence is....a small peptide (e.g. insulin)? or a larger protein (e.g. actin/ATPase)
Definitely infinite, depends on the following factors:
*Whether amino acids repeat in a sequence (they do frequently)
*How long the sequence is....a small peptide (e.g. insulin)? or a larger protein (e.g. actin/ATPase)
Is it that cells have different shapes and sizes ?
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