AP BIOLOGY

Detailed explanation-1: -Lambda exonuclease is a highly processive 5’–>3’ exonuclease that degrades double-stranded (ds)DNA. The single-stranded DNA produced by lambda exonuclease is utilized by homologous pairing proteins to carry out homologous recombination.

Detailed explanation-2: -Terminal deoxynucleotidyl transferase was discovered in 1960 when it was purified from a calf thymus gland (Bollum, 1960). The full length 58 kDa protein undergoes proteolytic degradation, generating fragments some of which still show enzymatic activity (Chang, Plevani, & Bollum, 1982).

Detailed explanation-3: -Terminal transferase (TdT) is a template independent polymerase that catalyzes the addition of deoxynucleotides to the 3’ hydroxyl terminus of DNA molecules. Protruding, recessed or blunt-ended double or single-stranded DNA molecules serve as a substrate for TdT.

Detailed explanation-4: -Terminal transferase: It is the enzyme that converts blunt end of DNA fragments into sticky end. If the restriction enzyme cuts DNA forming blunt ends, then efficiency of ligation is very low. So the enzyme terminal transferase converts bunt end into sticky end.