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Sequence Alignment Examples. Fall 2003 Dr. Susan Bridges. Global Alignment Example. Different scoring functions can be used with any of the algorithms. For this example, use the following scoring function: Indel (add a space) -2 Match +2 Substitution -1. Global Alignment Result.
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Sequence Alignment Examples Fall 2003 Dr. Susan Bridges Department of Computer Science and Engineering Bioinformatics
Global Alignment Example • Different scoring functions can be used with any of the algorithms. • For this example, use the following scoring function: • Indel (add a space) -2 • Match +2 • Substitution -1 Department of Computer Science and Engineering Bioinformatics
Global Alignment Result A A C C C T A A G C C T T _ | | | | | | | Department of Computer Science and Engineering Bioinformatics
Local Alignment • For this example, use the following scoring function: • Indel (add a space) -2 • Match +2 • Substitution -1 • A zero entry stops a local alignment so it is not necessary to keep track of the source of 0 entries Department of Computer Science and Engineering Bioinformatics
Finding Local Alignments • There may be several local alignments • Each local alignment begins from the largest value in the table and works back to a value of 0. • Symbols after the last non-zero entry (working backward) and before the maximum value (working backward) are not considered to be aligned. Department of Computer Science and Engineering Bioinformatics
Local Alignment Result A A C C C T A _ A G C C T T | | | | | Department of Computer Science and Engineering Bioinformatics
Semi-Global Alignment • For this example, use the following scoring function and global procedure: • Indel (add a space) -2 • Match +2 • Substitution -1 • Initialize first row to 0’s • Select largest value in border row and column (last row and last column) as beginning of alignment. Trace back from this value until encounter first row or first column. Department of Computer Science and Engineering Bioinformatics
Semi Global Alignment A A G C C T G C C T T | | | | Department of Computer Science and Engineering Bioinformatics