Biological sequences evolve through a process of mutation and natural selection. By comparing two sequences, we can determine whether two sequences have a common evolutionary origin if their similarity is unlikely to be due to chance. Before we get into how this is done, we must also consider that there are many types of evolutionary relationships among sequences.

Sequence alignment is the process of arranging the characters of a pair of sequences such that the number of matched characters is maximized.

in this Course, we will be learning the topic of sequence Alignment. its history and elevation of sequence alignment throughout the history, explaining the aligned sequences.

Also, we will be covering the types of sequence Alignment

Local and Multiple Alignment

Pairwise sequence alignment methods are used to find the best-matching piecewise (local or global) alignments of two query sequences. Pairwise alignments can only be used between two sequences at a time, but they are efficient to calculate and are often used for methods that do not require extreme precision (such as searching a database for sequences with high similarity to a query). The three primary methods of producing pairwise alignments are dot-matrix methods, dynamic programming, and word methods; however, multiple sequence alignment techniques can also align pairs of sequences. Although each method has its individual strengths and weaknesses, all three pairwise methods have difficulty with highly repetitive sequences of low information content - especially where the number of repetitions differs in the two sequences to be aligned.

Multiple sequence alignment is an extension of pairwise alignment to incorporate more than two sequences at a time. Multiple alignment methods try to align all of the sequences in a given query set. Multiple alignments are often used in identifying conserved sequence regions across a group of sequences hypothesized to be evolutionarily related. Such conserved sequence motifs can be used in conjunction with structural and mechanistic information to locate the catalytic active sites of enzymes. Alignments are also used to aid in establishing evolutionary relationships by constructing phylogenetic trees. Multiple sequence alignments are computationally difficult to produce and most formulations of the problem lead to NP-complete combinatorial optimization problems.

We Will also discuss the tools used for Sequence Alignment in pairwise and multiple alignments.