Global Alignment Algorithm Explanation
The question asks for the method used for global alignment of two protein sequences. Global alignment aims to find the best possible alignment across the entire length of two sequences.
Needleman-Wunsch Algorithm
The Needleman-Wunsch algorithm is specifically designed for global sequence alignment. It computes an optimal global alignment score by comparing two sequences from beginning to end using dynamic programming.
- It guarantees finding the alignment with the highest possible score across the full length of both sequences.
- It is widely used in bioinformatics for comparing related DNA, RNA, or protein sequences.
Other Methods Analysis
Let's analyze why the other options are not suitable for global alignment:
- Chou-Fasman method and Garnier-Osguthorpe-Robson (GOR) method: These methods are used for predicting the secondary structure of a *single* protein sequence (e.g., alpha-helix, beta-sheet content), not for aligning two sequences.
- Smith-Waterman algorithm: This algorithm is used for local alignment, which finds the best-scoring *subsegment* alignment between two sequences. It does not align the entire length.
Therefore, the Needleman-Wunsch algorithm is the correct choice for global alignment of two protein sequences.
Important Questions from Methods in Microbiology
- Which one of the following programs is used for finding distantly related (or remote) protein homologs?
- Correctly match the following Bioinformatic tool/Database with its respective Utility.
Bioinformatic tool/Database Utility P. BLAST 1. Database for 3D protein structures Q. Bowtie 2. Tool to identify similarity of a query sequence to existing sequences available in databanks R. AlphaFold 3. Tool to align short read DNA sequences obtained from Next-generation sequencing to a reference genome S. PDB 4. AI tool to predict protein structures - Which of the following is NOT used for generating an optimal alignment of two nucleotide sequences?
- Which one of the following BLAST search programs is used to identify homologs of a genomic DNA query in a protein sequence database?
Consider the following alignment of two DNA sequences:
AGTAAC
AA--AC
Assuming an affine gap scoring scheme of an identity matrix for substitution, a gap initiation penalty of 1 and a gap extension penalty of 0.1, the score of the alignment is (up to one decimal place)_______.
