Question

On a hypothetical island virus outbreak becomes a threat of future pandemic. Researchers have narrowed down the cause of outbreak to two viruses (virus 1 and virus 2). The DNA sequencing lab receives a sample for further analysis. Unfortunately, the sample was contaminated and the removal of foreign DNA leaves the lab with a short DNA fragment: AGCAGCTTCCAG. Given all available information (provided below) how can lab determine the type of the virus that caused the outbreak?

Nucleotide probabilities of virus1
P(A)=P(T) =0.35
P(G)=P(C) = 0.15
Nucleotide probabilities of virus 2
P(A)=P(T)=P(G)=P(C)= .25

Assume:

- Virus 1 and Virus 2 are equally likely to occur in nature.
- nucleotides are independent and identically distributed

Hints:

1. Consider sequence of dice rolls 61325 when thinking about DNA sequence.
2. What if Virus 1 and Virus 2 were not equally likely to occur? How would that change your answer?

Answer 1