Question

Saul Needleman and Christian Wansch postulated an algorithm which is useful for

• A. Multiple sequence alignment
• B. Global alignment of sequence
• C. Local alignment of sequence
• D. Progressive alignment

Hint:

Global alignment is useful when comparing two sequences of similar length and overall evolutionary relationship, where the entire sequence needs to be aligned.

Answer 1

The Correct Option is B

Saul Needleman and Christian Wansch developed an algorithm in 1970 that is specifically used for global sequence alignment. This algorithm aligns two sequences in their entirety, ensuring the best possible match from one end of the sequences to the other, including gaps when necessary.

(1) Global Alignment of Sequences:
- This type of alignment attempts to align the entire length of two sequences, considering the best global match between them.
- It is particularly useful when the sequences being compared are of similar length and are evolutionary related over the entire sequence.

(2) Why Other Options Are Incorrect:
- Multiple Sequence Alignment (Option 1) involves aligning more than two sequences, which requires different algorithms, like ClustalW, not the Needleman-Wunsch algorithm.
- Local Alignment of Sequences (Option 3) is used for aligning regions of high similarity within two sequences, and the Smith-Waterman algorithm is commonly used for this purpose.
- Progressive Alignment (Option 4) is typically used in multiple sequence alignment algorithms (like ClustalW), but it is not the focus of the Needleman-Wunsch algorithm.

Conclusion: The Needleman-Wunsch algorithm is designed for global alignment of sequences, aligning two sequences in their entirety to maximize their overall similarity.