Question

Although many cloning applications involve introducing recombinant DNA into bacterial host cells, many other cell types are also used as hosts for recombinant DNA. Why?

Short answer

Answer: Other cell types, such as yeast, insect, and mammalian cells, are used as hosts for recombinant DNA because they offer certain advantages over bacterial cells in terms of protein production, folding, and modification. These cell types can perform eukaryotic post-translational modifications, process introns, and produce properly folded and modified proteins, making them suitable for various biotechnology applications and the production of therapeutic proteins.

Step-by-step solution

Understanding recombinant DNA technology

Recombinant DNA technology is a technique used to join together DNA molecules from two different species that are inserted into a host organism to produce new genetic combinations that are valuable to science, medicine, agriculture, and industry. Bacterial cells, such as Escherichia coli (E. coli), are commonly used as host cells for recombinant DNA.

Characteristics of bacterial cells as hosts

Bacterial cells like E. coli are easy to grow and manipulate in the laboratory, have fast reproduction rates, and contain plasmids - small, circular, double-stranded DNA molecules that can be easily extracted, modified, and reintroduced into bacterial cells. Plasmids can act as vectors, carrying the desired DNA fragment into the host cells. Additionally, E. coli and other bacterial cells can be easily screened for the presence of recombinant DNA using antibiotic resistance markers.

Limitations of bacterial cells as hosts

Despite their advantages, bacterial cells have some limitations when used as hosts for recombinant DNA. They lack the machinery needed to perform eukaryotic post-translational modifications, such as glycosylation or phosphorylation; they may not efficiently process introns, which are common in eukaryotic genes; and some eukaryotic proteins may become insoluble or form inclusion bodies in bacterial cells, making them inactive or difficult to purify.

Other cell types as hosts for recombinant DNA

To overcome these limitations, other cell types are used as hosts for recombinant DNA, such as yeast, insect, and mammalian cells. Yeast cells have some advantages over bacteria, including the ability to perform post-translational modifications and properly process introns. Insect cells, often used in combination with baculovirus vectors, can produce large amounts of properly folded and modified eukaryotic proteins. Mammalian cells, such as Chinese hamster ovary (CHO) cells, can accurately produce, fold, and modify complex eukaryotic proteins, making them suitable for the production of therapeutic proteins and other biotechnology applications.

Conclusion

Although bacterial cells are commonly used as hosts for recombinant DNA, other cell types are also used because they offer certain advantages over bacteria in terms of protein production, folding, and modification. Each host cell type has its unique characteristics and is chosen based on the specific requirements of the recombinant DNA and desired protein product.