Combination problem for AA sequence

[Ashish]

Advertisement - Members don't see this ad

So if there area 5 different AA in a polypeptide, what is the possible number of sequence of nucleotide?

Different sources say it is 5!= 120 but I don't understand why?

Thank you!

 

[gangazi]

So if there area 5 different AA in a polypeptide, what is the possible number of sequence of nucleotide?

Different sources say it is 5!= 120 but I don't understand why?

Thank you!

 

[Roy Williams]

It's a permutation. Same kind you should be studying for the QR section. 5P5 = 5!/(5-5)! = 5! = 120

If you have any other questions about this kinda stuff let me know!

 

[Ashish]

It's a permutation. Same kind you should be studying for the QR section. 5P5 = 5!/(5-5)! = 5! = 120

If you have any other questions about this kinda stuff let me know!

Three nucleotide makes 1 AA though and there are wobble bases where the 3rd of the 3 does not matter so first 2 really produces a unique AA. How do you incorporate this?

 

[Roy Williams]

What do you mean three nucleotides makes an amino acid? I was always under the impression that three nucleotides made a codon which codes for an AA. When the question says what is the possible number of sequences of nucleotides, I interpreted that as each sequence being a set of three nucleotides. So in general it was just asking how many ways can you arrange the 5 amino acids.

 

[clutchfans]

Three nucleotide makes 1 AA though and there are wobble bases where the 3rd of the 3 does not matter so first 2 really produces a unique AA. How do you incorporate this?

yeah, the question doesn't mention anything about codons so don't make it more complicated than it is.

 

[Ashish]

Draw 5 boxes
First box -- 5 diff AA can fill
second box -- 4 other diff AA ( excluding the one that filled the first one)

Do this until 5th box you got
5*4*3*2*1

This makes sense.

What do you mean three nucleotides makes an amino acid? I was always under the impression that three nucleotides made a codon which codes for an AA. When the question says what is the possible number of sequences of nucleotides, I interpreted that as each sequence being a set of three nucleotides. So in general it was just asking how many ways can you arrange the 5 amino acids.

I meant combination of three bases makes 1 codon. I see what is going on here more clearly now. I was making things more complicated by considering the sequence of bases rather than just 5 distinct AA. Thanks.