why do you need a triplet of DNA bases to code for an amino acid ?

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0603
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^^
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StriderHort
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2 is not enough, 4 is too many is my tough'n'ready way of understanding it

for the 20 amino acids in genetic code (plus the 'others') you're going to need at least 20 codes (plus stop/start codes). There are 4 bases, (A,T/U,G,C). so 1 pair of bases has 4 possibilities right? Therefore 2 pairs of bases has 16 possible codes (4x4), still not enough, so it needs to go to 3 pairs in a row ( aka a codon) to give it 4 x 4 x 4 for 64 possibilities. That's plenty so no need for 4 pairs. (Although i think adding 4's and 5's is part of genetic engineering, I see people adding X's and crap like that )
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Bio 7
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Methionine is the start amino acid, every protein chain beings with one. Answer above covers the rest I think.
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(Original post by StriderHort)
2 is not enough, 4 is too many is my tough'n'ready way of understanding it

for the 20 amino acids in genetic code (plus the 'others') you're going to need at least 20 codes (plus stop/start codes). There are 4 bases, (A,T/U,G,C). so 1 pair of bases has 4 possibilities right? Therefore 2 pairs of bases has 16 possible codes (4x4), still not enough, so it needs to go to 3 pairs in a row ( aka a codon) to give it 4 x 4 x 4 for 64 possibilities. That's plenty so no need for 4 pairs. (Although i think adding 4's and 5's is part of genetic engineering, I see people adding X's and crap like that )
what do you mean by "1 pair of bases has 4 possibilities" ? do you mean that 1 pair of bases can produce 4 possible different amino acids ?
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Jamie_1712
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(Original post by 0603)
what do you mean by "1 pair of bases has 4 possibilities" ? do you mean that 1 pair of bases can produce 4 possible different amino acids ?
Ok so imagine that it was just 1 base per codon. You could have a maximum of 4 different codons right? 2 bases per codon is 16 different codons. That’s still not enough as there are about 20 amino acids. Therefore we need 3 bases per codon, giving 64 codons. This is way more than needed so each amino acid often has multiple codons that code for it. This means it is a degenerative code.
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StriderHort
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(Original post by 0603)
what do you mean by "1 pair of bases has 4 possibilities" ? do you mean that 1 pair of bases can produce 4 possible different amino acids ?
No The Amino acid is composed of 3 Base Pairs, A single 'Base Pair' (aka a Nucleotide?) has 4 base possibilities, either A-T, T-A, G-C or C-G (not counting the T/U thing). But if nature has at least 20 amino acids to code, nature needs a genetic code with more possibilities, if we go to 2 base pairs, we still only have 16, so it HAS to go to 3 pairs. (4x4x4)

(I'm totally not a biochemist, I study plants, I may be slightly off)
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0603
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ohhhhh ok i think i've got it now. does this image depict what you're explaining http://biology.kenyon.edu/courses/bi...Chapter05.html
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(Original post by StriderHort)
No The Amino acid is composed of 3 Base Pairs, A single 'Base Pair' (aka a Nucleotide?) has 4 base possibilities, either A-T, T-A, G-C or C-G (not counting the T/U thing). But if nature has at least 20 amino acids to code, nature needs a genetic code with more possibilities, if we go to 2 base pairs, we still only have 16, so it HAS to go to 3 pairs. (4x4x4)

(I'm totally not a biochemist, I study plants, I may be slightly off)
ok i understand it now. thank you
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StriderHort
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(Original post by 0603)
ohhhhh ok i think i've got it now. does this image depict what you're explaining http://biology.kenyon.edu/courses/bi...Chapter05.html
Yup, that's the 64 codon possibilities and the 20 Amino acids they create plus the start/stop ones.
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