The polymerase chain reaction (PCR) is used to generate: multiple copies of a targeted region of DNA. a single copy of a targeted region of DNA. single copies of whole chromosomes. multiple copies of whole chromosomes. multiple copies of whole chromosomes and a targeted region of DNA.

multiple copies of a targeted region of DNA.

Explanation: Polymerase chain reaction is a technique used in molecular biology to produce millions of copies of specific DNA segment. This involves taking a minute sample of DNA segment and hugely amplifying it to produce multiple copies of the segment. PCR procedure has three step:

1). Heating the double stranded DNA containing the targeted DNA region to be amplified in order to separate the strands.

2). Allowing the strands to cool and adding synthetic oligonucleotide primers.

3). Addition of thermostats DNA polymerase to catalyze 5'->3' DNA synthesis.

The process is repeated in about 25 to 30 cycles and the amplified DNA can be cloned.

PCR was invented in 1983 by Kary Mullis.