Unformatted text preview: starting a new codon or ACT could be a codon with the first A the last letter of a previous codon. But AAC and ACT cannot both be codons at the same time. Rule 3 The final rule states that once you begin reading the code from a specific nucleotide, you continue reading it by threes until the end. The beginning of an amino acid sequence is specified by a start codon located somewhere in the mRNA sequence, this is usually an AUG, but can also be a GUG. The end of a sequence is specified by one of three stop codons: UAA, UAG, or UGA. A consequence of this rule is that the genetic code can be read in three different reading frames depending on which base one begins with. For example, the sequence: ACGACGACGACGACG can be read in the three following ways. 1.) ACG ACG ACG ACG ACG (each codon specifies the amino acid threonine) 2.) A CGA CGA CGA CGA CG (each codon specifies the amino acid arginine) 3.) AC GAC GAC GAC GAC G (each codon specifies the amino acid asparagine...
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This note was uploaded on 01/27/2012 for the course BIOLOGY BSC1005 taught by Professor Rodriguez during the Winter '09 term at Broward College.
- Winter '09