Which one of the following is comparatively the best E-value to a pairwise sequence match?
Which one of the following is comparatively the best E-value to a pairwise sequence match?
Select an option to attempt
Correct Answer: Option A
Explanation
E-value in BLAST: lower is better (more significant):The E-value (Expect value) in BLAST represents the number of random database hits expected with a score equal to or better than the observed score:where m = query length, n = database size,= Karlin-Altschul parameter, S = alignment score.Interpretation:• E-value of(0.0001): Only 0.0001 random hits expected → HIGHLY SIGNIFICANT — BEST CHOICE• E-value of= 0.01: 0.01 random hits expected• E-value of= 1.0: 1 random hit expected (borderline)• E-value of= 100: 100 random hits expected → LEAST SIGNIFICANTRule: LOWER E-value = MORE SIGNIFICANT match.Typical significance thresholds:• E <: Very significant (homologous)• E < 0.01: Likely significant• E > 1: Not significant (chance match)Answer:(= 0.0001) is the best (most significant) E-value.