EcoRI makes staggered cuts when it cleaves DNA, creating single-stranded tails called "sticky ends." These ends can bind to complementary bases.Assuming that concentration of the cut DNA strands is not rate limiting, in order for the complementary ends to base pair, which condition is necessary?
A) The presence of specific helicases
B) Sufficiently high temperature
C) The presence of methyl groups at the end of each DNA strand
D) Sufficiently low temperature
E) Phosphodiester bonds between the complementary DNA strands

Question

Quizplus · Accepted Answer

Base pairing between complementary single-stranded DNA tails is a process driven by hydrogen bonding. Hydrogen bonding is a temperature-dependent process, and the optimum temperature for hydrogen bonding is relatively low (<65°C). Therefore, a sufficiently low temperature is necessary for base pairing between complementary DNA strands. The presence of helicases would be irrelevant since they are involved in unwinding double-stranded DNA, and this scenario involves single-stranded DNA tails. The presence of methyl groups would hinder base pairing since they are large chemical groups that would block binding. Phosphodiester bonds are the covalent bonds that connect adjacent nucleotides, and they are not directly involved in hydrogen bonding between complementary DNA strands.

EcoRI Makes Staggered Cuts When It Cleaves DNA, Creating Single-Stranded