Biology 11th Edition by Gerald Audesirk,Teresa Audesirk,Bruce Byers

Exercise 10

Genetic information is encoded in the sequence of nucleotides in DNA. Let's suppose that the nucleotide sequence on one strand of a double helix encodes the information needed to synthesize a hemoglobin molecule. Do you think that the sequence of nucleotides on the other strand of the double helix also encodes useful information? Why? (An analogy might help. Suppose that English were a "complementary language," with letters at opposite ends of the alphabet complementary to one another; that is, A is complementary to Z, B to Y, C to X, and so on. Would a sentence composed of letters complementary to "To be or not to be?" make sense?) Finally, why do you think DNA is double-stranded?