(i) PCR is a very sensitive technique which enables the amplification of desired DNA from a limited amount of DNA template.
(ii) A technique can be also used for amplifications of RNA in which case it is referred to as reverse transcription PCR (RT-PCR). In this process the RNA molecules (mRNA) must be converted to complementary DNA by the enzyme reverse transcriptase (reverse transcription).
(iii) The cDNA then serves as the template for PCR.
(iv) The specificity and sensitivity of PCR is useful for the diagnosis of inherited disorders (genetic, viral; bacterial, diseases).
(v) Hence, it can detect the presence of an infectious organism in the infected patient at an early stage of infection (even before the infectious organism has multiplied into large number).

(i) Human growth hormones somatostatin and somatotropin such as are peptide hormones secreted by the pituitary gland that helps in the growth and development by increasing the uptake of amino acids and promoting protein synthesis. Deficiency of human growth hormone causes dwarfism, which could be treated by injecting hGH extracted from the human pituitary glands.
(ii) Using recombinant DNA technology hGH can be produced. The gene for hGH is isolated from the human pituitary gland cells.
(iii) The isolated gene is inserted into a plasmid vector and then is transferred into E. coli.
(iv) The recombinant E. coli then starts producing human growth hormone. The recombinant E. coli are isolated from the culture and mass production ofhGH is carried out by fermentation technology.
(v) A recombinant form of a human growth hormone called somatropin is used as a drug to treat growth disorders in children.

1. Production of insulin by recombinant DNA technology started in the late 1970s.
2. This technique involved in the insertion of human insulin gene on the plasmids of E. Coli. The polypeptide chains are synthesized as a precursor called pre-proinsulin as it contains A and B segments linked by a third chain (c) and preceded by a leader sequence.
3. The leader sequence is removed after translation and 'c' chain is excised, leaving the A and B polypeptide chains.
4. Insulin was the first ever pharmaceutical product of r-DNA, technology.

Advantages
1. Offers benefits for clinical traits and medical research.
2. It can help in the production of help in the production of proteins and drugs in the field of medicine.
3. Aids in stem cell research
4. Animal cloning could help to save endangered species.
Disadvantages
1. In animal and human activities, it as a threat to biodiversity saying that this alters evolution which will have an impact on populations and ecosystem.
2. The process is tedious and very expensive.
3. It can cause animals to suffer
4. Reports show that animal surrogates were manifesting adverse outcomes and cloned animals were affected with disease and have high mortality rate.
5. It might compromises human health through consumption of cloned animal meat.
6. Cloned animals age faster than normal animals and are less healthy than the parent organisms as discovered in Dolly.
7. Cloning can lead to occurrence of genetic disorders in animals.
8. More than 90% of cloning attempts fail to produce a viable offspring.