(a) (A) - AATTC /Sticky end
(B) Ori / Origin of Replication
(b) Palindromic sequence, because the sequence of base pairs reads same on the two strands when orientation of reading is kept the same.
(c) PCR - Polymerase Chain Reaction
Importance - amplification of gene of interest (in vitro)
Detailed Answer:
(a) The part labelled A is the sticky end. The part labelled B is the foreign DNA insert.
(b) The term used for A and C are called the palindromic nucleotide sequence. These are named so because they read the same forward and backward.
(c) PCR stands for Polymerase Chain Reaction.
PCR is a technique in molecular biology, used to amplify a gene or a piece of DNA to obtain its several copies. It is extensively used in the process of gene manipulation.