MCAT ? of the day 9/27/10

[Ginger Ale]

I'm not quite sure how to approach this question. At first I thought it was pretty straight forward, but was baffled by their explanation...

Can anyone shed some light on this problem?



Two different restriction enzymes cut at specific sequence sites on DNA fragments. The cut DNA fragments are then placed with DNA ligase to ligate compatible fragments. Which of four fragments will ligate with the following fragment:

-C
-GTTACA

Note: The dashes indicate continuing sequence.
(a)
-CTGTAA
-G

(b)
-AATGT
-T

(c)
-TGTAA
-A

(d)
-CAATGT
-G



Thank!

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[Mithril]

Well, isn't it C?

 

[Ginger Ale]

nope, it's A

 

[Rabolisk]

Just put the top strands together and the bottom strands together, noting that you have to reverse the direction from the one written. Then you will see that the strands are complementary to each other. -CAATGTC- and -GTTACAG-. Seems like a straightforward problem to me.