A DNA-Binding Protein Recognizes a Specific Eight-Nucelotide Sequence in DNA

Multiple Choice

A DNA-binding protein recognizes a specific eight-nucelotide sequence in DNA. Assuming that its binding is perfectly specific, how many binding sites are expected to exist for it in human genomic DNA, which is composed of about 6 × 10⁹ nucleotide pairs? What about if the protein forms a homodimer? Note that the target sequence can be oriented either way in the double-stranded DNA.

A) About 200,000; about 30,000
B) About 2000; about 300
C) About 200; about 30
D) About 200,000; about 300
E) About 200,000; about 3