Question

First artificial gene synthesized by Khorana was
A. Nif
B. Restriction endonuclease
C. RNA synthetase
D. Yeast alanine tRNA synthetase

Answer 1

Hint: Artificial gene synthesis or gene synthesis is a group of methods to synthesis and arrange genes in the nucleotide. It is a method used in the field of synthetic biology. This does not require a template DNA strand.

Complete answer: H.G. Khorana and his team synthesized the first artificial gene in yeast which coded for the enzyme involved in the transfer RNA or tRNA synthesis. The first complete product was yeast tRNA. The tyrosine tRNA precursor was of amino acid tyrosine. It possesses 126 nucleotides. Then the biological gene was synthesized artificially.
Considering the other options:
-Nif is involved in nitrogen-fixing, which are the genes that encode the enzymes required for the fixation of atmospheric nitrogen making it available for higher plant species. The nitrogenase complex in nif genes helps in converting the nitrogen present in the atmosphere to be converted to ammonia, which can be utilized by plants. It also functions in regulating the proteins which have a role in nitrogen fixation. These genes can be found in many bacteria that are free-living and also in the nitrogen-fixing symbiotic bacteria.
-Endonucleases are the enzymes that help in recognizing specific nucleotide sequences in a DNA strand, and cuts the strand at specific sites, to produce a specific sequence. It is a major enzyme involved in the process of recombinant DNA synthesis.
-RNA synthetase enzyme is also called RNA replicase is an enzyme whose role is in catalyzing the process of RNA synthesis, in the cells which have been infected with viral cells. This enzyme can also be used in the process of recombinant DNA production.
Thus, the most appropriate answer is D, yeast alanine tRNA synthetase.

Note: The recombinant DNA technology or the rDNA technology is the method by which new DNA molecules are produced in-vitro or in a laboratory by the combination of genetic materials from different sources, this method is also an example of genetic recombination. It is a widely used application involved in the process of genetic engineering.