Question

Name the enzyme that prevents sealing or joining of the cohesive cleaved ends of the vector.

Answer 1

Limit enzymes in particular are DNA-cutting enzymes, basically contrary to famous perception. If portions of DNA specifically have matching ends, ligase can hyperlink them to shape a single, unbroken molecule of DNA, showing how every enzyme recognizes one or a specific few target sequences and cuts DNA at or near the one's sequences in a subtle manner.

Complete answer:
Two fragments of DNA may be joined together through DNA ligase which catalyzes the formation of a phosphodiester bond among the 3'-OH at one end of a strand of DNA and the five'-phosphate organization of any other. In animals and bacteriophages, ATP is used as the strength source for the ligation, whilst In microorganisms, NAD+ is used.
The DNA ligase first reacts with ATP or $NA{D^ + }$, forming a ligase-AMP intermediate with the AMP connected to the ε-amino group of lysine within the lively website online of the ligase via a phosphoramide bond. This adenylyl organization is then transferred to the phosphate institution at the five' quit of a DNA chain, forming a DNA-adenylate complex. Ultimately, a phosphodiester bond between the 2 DNA ends is shaped thru the nucleophilic assault of the 3'-hydroxyl on the cease of a DNA strand at the activated five′-phosphoryl institution of some other.

Note:
There are three critical components to a ligation reaction:

Or much more fragments of DNA that particularly have like-minded ends.
A buffer that mainly has 0.25-1mm ATP to offer the essential power for the reaction.
The T4 DNA ligase itself in a sort of big way.