Consider the following statements (A-D) and select the option stating which ones are true (T) and false (F).
A. The first clinical gene therapy was carried out in 1991.
B. A short single stranded DNA or RNA tagged with a radioactive molecule to detect the complementary strand is called a probe.
C. The amplification technique used for obtaining multiple copies of specific sequences of DNA is called PCR.
D. The mature proinsulin contains A and B polypeptides linked together by disulphide bonds.

The correct option is A A - F, B - T, C - T, D - F
The first gene therapy was carried out on September 14, 1990 by a team of workers led by Blaese and Anderson at the National Institute of Health, USA for a 4 year old girl with ADA deficiency, named Ashanti.

A short single stranded DNA or RNA tagged with a radioactive molecule to detect the complementary strand is called a probe. Gene probes are small. Tagged with a label like color or fluorescence, gene probes allow researchers to identify a specific sequence of DNA in a mixture.

PCR stands for polymerase chain reaction. PCR is a method widely used to rapidly make millions of copies of a particular sequence of a specific DNA sample. It is based on the basic principle of enzymatic replication of the nucleic acid. It uses DNA polymerase for an in vitro replication of specific DNA sequences.

Proinsulin is the final single chain protein structure secreted by the beta cells of the pancreas before cleavage into mature insulin. The mature insulin has A and B polypeptides linked together by disulphide bonds and it is devoid of C peptide.