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can you tell me how to find solution to this question

A DNA chip contains a complete set of random hexanucleotide (6-mers) probes. Out of the 4^6 = 4096 probes, how many will form perfect complementary duplexes with sequences within the single-stranded target DNA, 5'-GAACTGCATTGATA-3'?

Answers: a. 1 b. 3 c. 6 d. 9 e. 12

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closed as off topic by Michael Kuhn, Mad Scientist May 7 '12 at 9:56

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Have you attempted this yourself before? People here generally refrain from helping with homework, so unless you show what you have done yourself and ask a specific question about a problem which you had with solving this, you are unlikely to get an answer. –  Armatus May 7 '12 at 8:15
i have tried this but i am not able to find a way to solve this problem..if you know the logic of solving this problem please tell me..the answer which i thought was correct is a (1) but its not the correct answer –  Eka May 7 '12 at 9:07
Please show exactly how you tried to solve the problem yourself and how far you got. Specific questions about homework exercises are okay here, but please don't just paste the assignment and ask us to do all your work for you. –  Mad Scientist May 7 '12 at 9:57
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1 Answer

up vote 2 down vote accepted

The DNA chip contains a complete set of random hexanucleotides.

This means it contains a collection of sets of 6 nucleotides. It is complete, this means that every possible combination of 6 nucleotides is present in it. From AAAAAA over anything like GCTTAG all the way to TTTTTT.

What you need to find out is: How many combinations of 6 nucleotides are there where all six of the nucleotides would fit exactly onto 6 consecutive nucleotides of GAACTGCATTGATA?

One example: The hexanucleotide CTTGAC would fit onto the first 6 bases in your target sequence.

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