Because eukaryotic genes contain introns, their transcripts cannot be translated by bacteria, which lack RNA-splicing machinery. But if you want to engineer a bacterium to produce a eukaryotic protein, you can synthesize a gene without introns. A good way to do this is to __________.

• A. alter the bacteria so that they can splice RNA
• B. use a nucleic acid probe to find a gene without introns
• C. use a phage to insert the desired gene into a bacterium
• D. use a restriction enzyme to remove introns from the gene
• E. work backward from mRNA to make a version of the gene without introns

Answer: (E)

Verified step by step guidance

1. Understand that eukaryotic genes contain introns, which are non-coding sequences that need to be removed before translation. Bacteria lack the machinery to splice out these introns.
2. Recognize that to express a eukaryotic gene in bacteria, you need a version of the gene that does not contain introns.
3. Consider the process of reverse transcription, where you can use mature mRNA (which has already had its introns removed) as a template to synthesize complementary DNA (cDNA).
4. Realize that cDNA is a version of the gene that lacks introns, making it suitable for expression in bacteria.
5. Conclude that the best approach to engineer a bacterium to produce a eukaryotic protein is to work backward from the mature mRNA to create a cDNA version of the gene without introns.