Final answer:
In genomic complexity studies, different rates of DNA renaturation indicate the presence of multiple classes of DNA. Eukaryotic genomes often have highly repetitive, moderately repetitive, and unique DNA sequences, whereas prokaryotic genomes typically have a single class of unique sequences. Therefore, the presence of three renaturation rates suggest three classes of DNA. The correct option is C.
Step-by-step explanation:
When studying the complexity of genomic DNA, scientists Britten and Davidson found that eukaryotic genomes contain different classes of DNA based on their redundancy, which can be distinguished using the CoT (Concentration × Time) value during DNA renaturation. The presence of slow, moderate, and rapid renaturation rates indicates multiple classes of DNA.
This method reveals that some DNA sequences are more highly repetitive than others, some are moderately repetitive, and the rest are unique or single-copy sequences. Prokaryotic genomes, such as those of E. coli, typically show only one class of DNA, as they consist largely of unique, non-repetitive sequences.
In the hypothetical scenario describing the isolation and evaluation of the genome of a new species of insects, multiple rates of renaturation would suggest that there are different classes of DNA in the organism's genome.
Thus, if the data showed three distinct slopes in the CoT curve, this would indicate the presence of three classes of DNA in terms of sequence redundancy: highly repetitive, moderately repetitive, and unique sequences. Therefore, the correct answer to the student's question would be C) Three.