NASA astronauts come back from Mars with soil samples. As the world\'s most famo
ID: 85258 • Letter: N
Question
NASA astronauts come back from Mars with soil samples. As the world's most famous biochemist, they come to your lab for further analysis of the soil for signs of life/organic material. To your surprise, you find a unique species of bacteria growing in the samples. You can culture these bacteria, and start to isolate their DNA for sequencing (if it has similar properties to current DNA). Every time you sequence this alien DNA, you get inconsistent results. Further studying the DNA, you find that the DNA contains bases A, T, C, G, X and Y. X and Y are unknown bases unique to the DNA alphabet of this alien bacteria. X pairs with Y in the DNA. Structures of X and Y are shown below. i. What properties are unique to these unnatural bases compared to natural bases? Do you expect edge-to-edge binding of these bases why/why not? ii. From the properties you described above, could this influence the replication of this "alien" DNA, why or why not? iii. You can cleave a small segment of DNA from this "alien" bacteria. Using the correct dNTP's and ddNTP's, you find the sequence shown below. 5'-C G T T T C Y T T C T C-3' 3'-G C A A A G X A A G A G-5' Using NMR (NOESY) to determine the structure of this DNA segment, vaguely describe what kind of peaks you would look for in the spectrum to determine how the new base pair may/may not disrupt the B-DNA/helical structure. iv. Why would discovering these unnatural bases be important to science?Explanation / Answer
(I) these unnatural bases does not contain Nitrogen in purine ring which is required for hydrogen bonding and if it will not be available less hydrogen bond will be formed and edge to edge bonding will also be not possible.
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