This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Replication, Subject name: Biochemistry
Which of the following is not true about eukaryotic DNA ligase? 
Select and explain. 
A. Catalyses the formation of phosphodiester bond, B. NAD+ is energy source, C. ATP is the energy source, D. Can act only on dsDNA
B: NAD+ is energy source
Answer: B: NAD+ is energy source 
Explanation: NAD+ is the energy source for Prokaryotic DNA Ligase ATP is the energy source for Eukaryotic DNA Ligase Role of DNA Ligase: Sealing the single stranded nick during replication and repair. In Recombinant DNA technology, ligase is used to join two different DNA molecules. Enzyme Function Helicases Unwinding of DNA DNA Polymerase III Polymerization of deoxynucleotides Topoisomerases Cut and reseal DNA, Relieve positive supercoils, Don't use ATP Single Stranded Binding proteins (SSBs) Prevents reannealing or rejoining of two seperate strands DNA Primase Initiates synthesis of RNA primers DNA Ligase Creates 3'5' phosphodiester bond and seals nick Okazaki fragments on lagging strand by using ATP