What enzyme forms covalent bonds between restriction fragments?
Which statement regarding recombinant DNA is false?
a. Restriction enzymes cut DNA at palindromic sequences.
b. A single restriction enzyme can cut DNA sequences at several different recognition sites.
c. Restriction enzymes can create DNA fragments with “blunt ends.”
d. Complementary “sticky ends” can form hydrogen bonds with each other.
e. Restriction enzymes can create DNA fragments with “sticky ends.”
Answer to question 1
When one wants to put restriction fragments back together, there is one enzyme well-suited to the task: DNA ligase.
DNA ligase is an enzyme with multiple roles in cells. It serves to facilitate sealing repairs in damaged DNA, joins recombination fragments together (similar to the case here with restriction fragments), and a key role in DNA replication joining Okazaki fragments together as part of regular DNA replication activity in mitosis prior cell division.
Answer to question 2
Answer to question 3
Option b – A single restriction enzyme can cut DNA sequences at several different recognition sites.
A restriction enzyme or a restriction endonuclease identifies specific sequences in a DNA molecule. It can form sticky or blunt ends. The sticky ends are able to form hydrogen bonds with each other. These enzymes cut at palindromic sequences.
A single restriction enzyme can cut DNA at just one or very few (not several ) different recognition sites.