Question

The number of possible global alignments between two sequences of length N is _____

(a) \(\frac{2^N}{\sqrt{πN}}\)

(b) \(\frac{2^{2N}}{\sqrt{πN}}\)

(c) \(\frac{2^{(N-1)}}{\sqrt{πN}}\)

(d) \(\frac{2^{2N}}{\sqrt{N}}\)

I have been asked this question during an interview for a job.

My doubt is from Needleman topic in chapter Multiple Sequence Alignment of Bioinformatics

Answer 1

Right choice is (b) \(\frac{2^{2N}}{\sqrt{πN}}\)

For explanation I would say: By the total number of permutations and combinations option b gives the accurate number of possible global alignments between two sequences of length N. For two sequences of 250 residues this is 10^149.