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7. In samples of DNA isolated from two unidentified species of bacteria, X and Y, adenine makes up 32% and 17%, respectively, of the total bases. What relative proportions of adenine, guanine, thymine, and cytosine would you expect to find in the two DNA samples? What assumptions have you made? One of these species was isolated from a hot spring (64 0C). Which species is most likely the thermophilic bacterium, and why?

User RAGOpoR
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The relative proportions of adenine, guanine, thymine, and cytosine in species X and Y are not provided; assumptions made include equal proportions of A-T and G-C base pairs; the thermophilic bacterium is most likely species X due to its higher adenine content, suggesting adaptations for stability in a hot environment.

In the absence of specific information on the relative proportions of adenine (A), guanine (G), thymine (T), and cytosine (C) in species X and Y, a common assumption is that DNA typically forms base pairs in a complementary manner, where adenine pairs with thymine and guanine pairs with cytosine. This implies equal proportions of A-T and G-C base pairs in a stable DNA structure. Given that adenine makes up 32% of the total bases in species X and 17% in species Y, it suggests that species X has a higher overall A-T content, while species Y may have a higher G-C content.

Furthermore, the information that one of these species was isolated from a hot spring at 64°C provides additional context. Thermophilic bacteria, adapted to high-temperature environments, often exhibit increased stability in their DNA structures. The higher adenine content in species X aligns with the expected stabilization effect of A-T base pairs, as they form two hydrogen bonds compared to the three formed by G-C pairs. Therefore, based on the assumption of complementary base pairing and the higher adenine content in species X, it is likely that species X is the thermophilic bacterium adapted to the hot spring environment.

User Quangkid
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