The correct answer is C. Insert the gene into bacteria.
To produce a protein from a gene, one common method is to use recombinant DNA technology. In this process, the isolated gene responsible for the protein of interest is inserted into a host organism, often bacteria or yeast, which can then produce the protein.
Here's how it works:
1. **Isolate the gene:** The scientist has already isolated the gene responsible for the protein found in chicken liver.
2. **Insert the gene into bacteria:** The isolated gene is inserted into a bacterial host's DNA. This is typically done using a plasmid, a small, circular piece of DNA that can be easily manipulated and introduced into bacteria.
3. **Expression:** The bacteria, now containing the gene of interest, can be cultured and induced to express the protein. This is often achieved by adding certain chemicals or changing the growth conditions in a way that triggers the bacterial cells to produce the protein.
4. **Protein production:** As the bacterial cells grow and divide, they produce the protein encoded by the inserted gene. This protein can then be harvested and purified for further study or use.
Options A and B ("use reverse transcriptase on the gene" and "mix gene with a cDNA probe") are not the standard methods for protein production. Reverse transcriptase is used to convert RNA into complementary DNA (cDNA) and is typically employed in the generation of cDNA libraries for studying gene expression, while cDNA probes are often used in hybridization experiments to detect the presence of specific RNA molecules. Option D ("Find all the mRNA produced by the liver") is related to studying gene expression but doesn't directly produce the protein of interest.