Final answer:
A hairpin is a DNA structure where the strand folds back and forms a double-strand with itself. Sequence a. 5' GGGGTTTTCCCC 3' and d. 5' TTTTTTCCCCCC 3' could form hairpin structures, with sequence d being more likely due to direct complementarity.
Step-by-step explanation:
The question concerns the ability of DNA sequences to form hairpin structures. A hairpin in DNA is a structure where a single strand of DNA folds back on itself and forms a double-stranded region due to complementary base pairing. For a hairpin to form, there needs to be a sequence of nucleotides that is self-complementary. Looking at the given sequences:
- a. 5' GGGGTTTTCCCC 3' - This sequence can form a hairpin because the Gs can pair with Cs, forming a stable double-stranded region with a loop of Ts.
- b. 5' AAAAAAAAAAAA 3' - This sequence cannot form a hairpin as there is no complementary sequence for the As to pair with.
- c. 5' ACACACACACAC 3' - This sequence does not have an obvious complementary region, so it is unlikely to form a stable hairpin.
- d. 5' TTTTTTCCCCCC 3' - This sequence can form a hairpin since the Ts can pair with the Cs, creating a hairpin with a loop of Ts.
Therefore, option a and option d are sequences that could potentially form a hairpin structure, with sequence d being a more probable candidate due to the direct complementarity without any loop bases.