fw431
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Been working through a head start to AS Biology book and hit a source of ambiguity which i wondered if anyone could help with. The book describes how three bases in a row, a triplet, codes for one amino acid and how this affects the order of bases in the mRNA copy and the order of amino acids in the protein, providing the sequence AGACACAGAACC with 'ACC' being boxed as a triplet.

What i was wondering is if when taking the order of what's being coded for in terms of amino acids, if one would go AGA then GAC then ACA and so on, or if it is every three e.g. AGA, CAC, AGA, ACC. Any help would be much appreciated
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Eloades11
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(Original post by fw431)
Been working through a head start to AS Biology book and hit a source of ambiguity which i wondered if anyone could help with. The book describes how three bases in a row, a triplet, codes for one amino acid and how this affects the order of bases in the mRNA copy and the order of amino acids in the protein, providing the sequence AGACACAGAACC with 'ACC' being boxed as a triplet.

What i was wondering is if when taking the order of what's being coded for in terms of amino acids, if one would go AGA then GAC then ACA and so on, or if it is every three e.g. AGA, CAC, AGA, ACC. Any help would be much appreciated
Hi fw431, that is a very good question.

Codons are always non-overlapping codes in a genetic sequences. For example, the string GGGAAACCC, if read from the first position, contains the codons GGG, AAA, and CCC. This is simply how cells have evolved to behave. If it was the other was, then a simple mutation in one of the bases (mutation is a change in one of the bases in DNA, eg a guanine changed to an adenine during DNA replication) would have severe repercussions in protein translation.

Another feature of codons is that their coding is degenerate. This means that you may come across two different codons, as an example GAA and GAG, which both code for the same amino acid (in this case, glutamic acid). You will learn more about this and why this is the case when you come to study biology at A-level. A cool feature of this is that if the DNA has a GAA codon and this sequences is mutated to GAG, this is known as a silent mutation. Although there is a distinct chance in the DNA sequence, the sequence will still code for the same amino acid and will not affect protein structure or folding

If you have any more questions, feel free to ask
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fw431
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(Original post by Eloades11)
Hi fw431, that is a very good question.

Codons are always non-overlapping codes in a genetic sequences. For example, the string GGGAAACCC, if read from the first position, contains the codons GGG, AAA, and CCC. This is simply how cells have evolved to behave. If it was the other was, then a simple mutation in one of the bases (mutation is a change in one of the bases in DNA, eg a guanine changed to an adenine during DNA replication) would have severe repercussions in protein translation.

Another feature of codons is that their coding is degenerate. This means that you may come across two different codons, as an example GAA and GAG, which both code for the same amino acid (in this case, glutamic acid). You will learn more about this and why this is the case when you come to study biology at A-level. A cool feature of this is that if the DNA has a GAA codon and this sequences is mutated to GAG, this is known as a silent mutation. Although there is a distinct chance in the DNA sequence, the sequence will still code for the same amino acid and will not affect protein structure or folding

If you have any more questions, feel free to ask
Thank you, i really appreciate the answer and it's clarified a lot for me, plus it's made me even more excited for Biology at A-level, if while working through the book i have any more questions i'll be sure to ask
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