Aamc 11 #138

[gunj122]

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I'm not exactly sure of how this answer is true. If the addition of a nucleotide didn't eliminate or create a stop codon, isn't a reasonable conclusion then that the carboxy-terminal sequence is the same? And the addition caused a change at the amino-terminal end? I understand it can't be C and D, but how do I differentiate between A and B? Thanks!

 

[PiBond]

Proteins are made N-terminus to C-terminus. The only way to change the N terminus AA would be to change the start codon to something else other than methionine, which wouldn't happen because the ribosome needs it to begin translation. A more likely result would be the insertion of the nucleotide downstream which would ultimately affect the C-terminus (end of the protein).

Does that make sense?

 

[gunj122]

hm yea what you're saying makes sense about how the N-terminal can't be changed. I think what threw me off was that a nucleotide was inserted and there was no addition or elimination of a stop codon. I guess I didn't take into account that maybe the stop codon was changed from UAG to UAA or some other degenerate stop codon. Ergo, since there's only ONE possible codon for Meth, it can't be changed.

Thanks a lot!