Question

Please do e

6. A k-element DNA sequence is a string made up of k letters chosen from the set {A, C, G, T) with replacement. For example, here are some 4-element DNA sequences: ACCT, GTAT, GCTA, GGGG. Answer the following counting questions. How many distinct 4-element DNA sequences are there: a. in total? b. that do not contain the letter T? c. that do contain the letter T? d. that contain all four letters A, C, G, and T? e. that contain exactly two of the letters A, C, G, and T? (Examples include GAGA, GGTG, and ACCC.)

Answer 1

Camlin Page Date as you said only to do e. {A, C, K,I} wecan choose any two letter from available four Letters. - so, to tel available option = 4c2 ex... scarico, 64, 68),(4,7), CC,ce), (6,5), (45)} letter Now we have to arrange that fello im Helements. enco.64,C) choosen ^ 2 4 2 1 2 1 2 = 24 516 but there are possibility that all the Letter are same. There are two chance. en., 191,9, a, a), CC,C,,C) - so, we have to substruct it. in 4 position So, we can arrange two number which have both as a element a 16-2 =14 301 So, To tell DNA possible 6X14 ___ 4] CScanned with Camscanner

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