Question

Arrange the following symbols in a BLASTP sequence alignment result in order of their contribution to the overall quality of the alignment, with the best symbol at 1 and the least effective at #4.

Option 1: "+" (Match)
Option 2: "-" (Gap)
Option 3: " " (Space)
Option 4: "." (Low-Quality Match)

Answer 1

In BLASTP sequence alignments, the symbols are ranked by their contribution to the alignment quality as follows: '+' for matches, which are best, '.' for low-quality matches, '-' for necessary gaps with penalties, and spaces which contribute the least.

Step-by-step explanation:

To arrange the symbols in a BLASTP sequence alignment result according to their contribution to the overall quality of the alignment, we use the scoring guidelines provided by BLAST. A "+" indicates a match, which contributes positively to the alignment score, a "-" denotes a gap which is necessary at times but imposes a penalty, a " " (space) signifies no alignment, and a "." represents a low-quality match, which is not as good as a direct match but better than no alignment at all.

1. "+" (Match)
2. "." (Low-Quality Match)
3. "-" (Gap)
4. " " (Space)

The best symbol contributing to the alignment is the match ("+") since it increases the score. A low-quality match (".") is next, as it still represents similarity, though not as strongly. Gaps ("-") are penalized but may be necessary to achieve better overall alignment, making them better than no alignment at all. Spaces are the least contributive since they represent regions with no alignment.