Question

Bacteria genetically engineered to express a gene from a plant will

• A. Synthesise a protein with the same sequence of amino acids as in the plant and, therefore, the protein will have the same structure and function as in the plant.
• B. Synthesis a protein with essentially the same sequence of amino acids as in the plant with differences relating to different colon wobble rules between prokaryotes and eukaryotes
• C. Not be able to synthesise a protein due to the presence of exon splicing sequences in the DNA sequence from the plant
• D. Not be able to synthesise a protein because transaction is coupled with transaction and posttranscriptional processing does not occur in it.

Answer 1

The correct option is A Synthesise a protein with the same sequence of amino acids as in the plant and, therefore, the protein will have the same structure and function as in the plant.

When bacteria (a prokaryote) is engineered to express a gene from a plant (an eukaryote), a slightly different approach is used. Eukaryotic genes have both exons and Introns which are transcribed into the primary transcript. Primary transcript is then processed by splicing (removal of introns and joining of exons), capping and tailling to produce functional mRNAs. This functional mRNA is then expressed into proteins. Prokaryotes lack such machinery, hence expression of an eukaryotic DNA becomes difficult in prokaryotic cells. Therefore, scientists prepare cDNA from the functional nRNA (without introns) using reverse transcriptase. This DNA is incorporated into bacteria (or another prokaryotic cell) for expression of plant gene. Such foreign gene synthesises a protein with the same sequence of amino acids as in the plant, and therefore the proteins have the same structure and function as in the plant.

So, the correct answer is 'Synthesise a protein with the same sequence of amino acids as in the plant and, therefore, the protein will have the same structure and function as in the plant.'