Question

Production of a human protein in bacteria by genetic engineering is possible because:
A. Bacterial cells can carry out the RNA splicing reactions.
B. The mechanism of gene regulation is identical in humans and bacteria.
C. The human chromosome can replicate in bacterial cells.
D. The genetic code is universal.

Answer 1

Genetic engineering refers to the direct manipulation of the DNA to alter the organism's characteristics. In this, one of the base pairs (A-T or C-G) is deleted from a region of DNA or there is introduction of a copy of a gene. Human protein that is produced by bacteria is insulin.

Complete answer:
Genetic engineering is an emerging branch of biology in which recombinant DNA technology alters the genetic makeup of an organism. It helps in manipulation of genes. There are times when a gene from another species is added to an organism's genome to give it a desired phenotype. In this, a strand of DNA is taken and combined with the other piece of DNA in laboratory conditions.
Production of human proteins in bacteria is possible solely because of this technology. A small piece of DNA called plasmid is extracted from the bacteria which is then cut by molecular scissors in small sections. The gene for human insulin is inserted in the gap in the plasmid which now gets genetically modified. This genetically modified plasmid is now put into a new bacteria and is left to divide rapidly for the formation of human proteins. To create a large amount of the cells, this genetically modified protein is grown in a large fermentation vessel that is filled with nutrients. More the division takes place, the more protein is produced. After fermentation is completed, the mixture is filtered to release the protein.
Order of nucleotides in mRNA helps in determining the amino acid sequence in the polypeptide chain of the protein during translation. We all know that genetic codes are universal. The order of nucleotides is the same that will result in incorporation of the same amino acid during the process of translation. That is why the production of human protein is possible through genetic engineering.

So, option D is the correct answer.

Note-
Insulin used for diabetes was earlier extracted from pancreas of slaughtered cattle and pigs. In 1983, Eli Lilly, an American company, prepared two DNA sequences corresponding to A and B, chains of human insulin and introduced them in plasmids of E. coli to produce insulin chains. Chains A and B were produced separately, extracted and combined by creating disulphide bonds to form human insulin.