Introduction to Computational Biology Lecture # 5: PSI-BLAST

A biological problem can be partitioned to three layers: 1. Modeling Translating the real-life problem into a mathematical model. 2. Algorithms Solving the mathematical problem using relevant algorithms. It is critical to define the mathematical problem well, otherwise the algorithm may become cumbersome or provide weak results. 3. Validation Once we obtain the results, we want to verify that they are valid. There are two approaches for performing validation: • Statistical Validation e.g. checking the significance of the results P-Value, etc. • Biological Validation Comparing the results to ’wet’ tests at the laboratory, check if the results provide biological insights and if they make sense biologically, etc. The kind of problems we’ll encounter during the course: • Sequences (comparing, finding short subsequences, evolution of sequences). • Networks (genes interactions). • Gene Expression.