AP BIOLOGY

Detailed explanation-1: -The unpaired nucleotide produced by the action of restriction enzymes are referred as sticky ends. Sticky ends are very useful in rDNA because they can be used to join two different fragments of DNA that were isolated by the same restriction enzyme. So, the correct answer is “sticky ends"

Detailed explanation-2: -A ‘sticky’ end is produced when the restriction enzyme cuts at one end of the sequence, between two bases on the same strand, then cuts on the opposite end of the complementary strand. This will produce two ends of DNA that will have some nucleotides without any complementary bases.

Detailed explanation-3: -Restriction enzymes can create fragments with sticky ends, as is the case with the enzyme BamHI, or blunt ends, as with HaeIII (Table 8.1). Double bars indicate the cleavage site in the DNA strand. DNA ligases are used to join the fragments of DNA generated by restriction enzymes.

Detailed explanation-4: -After digestion of a DNA with certain Restriction enzymes, the ends left have one strand overhanging the other to form a short (typically 4 nt) single-stranded segment. This overhang will easily re-attach to other ends like it, and are thus known as “Sticky ends".