A primitive eukaryote was discovered that displayed a unique nucleic acid as its
ID: 20468 • Letter: A
Question
A primitive eukaryote was discovered that displayed a unique nucleic acid as its genetic material. Analysis provided the following information:1) The general X-ray diffraction pattern is similar to that of DNA, but with somewhat different dimensions and more irregularity.
2) A major hyperchromic shift is evident upon heating and monitoring UV absorption at 260 nm
3) Base-composition analysis reveals four bases in the following proportions:
Adenine 8%
Guanine 37%
Xanthine 37%
Hypoxanthine 18%
4) About 75% of the sugars are deoxyribose, while 25% are ribose.
Postulate a model for the structure of this molecule that is consistent with the observations.
Explanation / Answer
It is an RNA-DNA hybrid without thymine, uracil and cytidine, and with xanthine and hypoxanthine instead, and not fully a double helix throughout its entire length.