When DNA molecules from two different organisms are incubated together, some duplexes are formed by DNA strands from the two species. What indicates that such duplexes are less stable than those between strands from the same organism?
A)Heterogeneous duplexes melt at lower temperatures than homogeneous duplexes.
B)Heterogeneous duplexes melt at higher temperatures than homogeneous duplexes.
C)Heterogeneous duplexes are degraded faster.
D)Heterogeneous duplexes are degraded more slowly.
E)There is no difference in stability between homogeneous and heterogeneous duplexes.

Question

Quizplus · Accepted Answer

The melting temperature (Tm) is the temperature at which half of the DNA duplexes have denatured into single strands. Heterogeneous duplexes, formed by DNA strands from two different organisms, have less stable base pairing due to differences in nucleotide sequence. Therefore, the Tm of heterogeneous duplexes is lower than that of homogeneous duplexes formed by DNA strands from the same organism. Choice A correctly indicates that heterogeneous duplexes melt at lower temperatures than homogeneous duplexes.

When DNA Molecules from Two Different Organisms Are Incubated Together